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feature How Gan Cao works Zhang Zhicong answers Zou Runan By William Ceurvels Advisor Chang Tung ti China Medical University Taiwan In his B n J ng Sh Zh ng Commentary on the Classic of Materia Medica 1849 Z u Sh zi name Z u R n n identifies two formulas from the Shang Han Lun Discussion of Cold Damage in which Gan Cao appears to indirectly drain fire through supplementation Unfortunately the explanation Zou gives for this phenomenon is based on a misunderstanding of the concept of Heart fire borrowed from the P W i L n Discussion of the Spleen and Stomach This article re examines L D ngyu n s concept of Heart fire and deploys this concept to analyse the disease aetiology of the two formulas mentioned in Zou Runan s analysis Finally a pharmaco mechanism described by Zh ng Zh c ng is used to provide a complete description of how Gan Cao resolves the disease aetiologies of the two Shang Han Lun formulas This new understanding of the pharmaco mechanism of Gan Cao has broad applications in clinical and theoretical settings Li Dongyuan s Heart fire In his celebrated 1867 masterpiece of materia medica Ben Jing Shu Zheng the great Chinese medicine scholar Zou Runan advanced the claim that the main pharmacological action of Gan Cao is to soothe urgent diseases an action that stems from it having the sweetest flavour of any herb 1 All other actions of the herb according to Zou are just an extension of its urgencysoothing properties hu n j j To prove his point Zou presents an analysis of two formulas from the Shang Han Lun Zhi Zi Dou Chi jia Gan Cao Tang Gardenia and Prepared Soybean Decoction with Licorice and Gan Cao Tang Gan Cao Decoction in which Gan Cao indirectly exerts supplementing and fire draining effects through its primary urgency soothing action This notion of urgency soothing is a fairly common but very poorly defined property of Gan Cao What constitutes urgency How is it soothed Through the application of concepts from Zhang Zhicong s understanding of Gan Cao in 1 The Lantern 27

feature Reading Liu Ruojin Zou Runan and Li Dongyuan s commentaries it is hard not to be confused by the vagueness of this concept of urgencysoothing combination with a close analysis and critique of Zou Runan s commentary on the aforementioned Shang Han Lun formulas as presented in the Ben Jing Shu Zheng this essay will endeavour to provide a precise pharmaco mechanism for Gan Cao that vastly improves upon previous vague notions of harmonising and supplementing Zou s contention that Gan Cao s supplementing and fire draining properties are indirect consequences of its primary urgency soothing action is an idea lifted straight from Zou s main influence Ming dynasty polymath materia medica scholar Li Ru j n 2 In B n C o Sh Description of the Materia Medica 1664 Liu writes The collective actions of Gan Cao can be ascribed to its harmonising quality The primary action of this harmonising quality is urgency soothing Urgency soothing further promotes both draining and supplementation 3 Liu goes on to provide an example from Li Dongyuan s Pi Wei Lun of how these direct and indirect properties manifest Dongyuan writes when the Spleen and Stomach are deficient Heart fire overwhelms the Spleen Fire is bitter and urgent Use Gan Cao to relieve the urgency This fire cannot be drained using cold and bitter herbs It should be treated with sweet and neutral herbs to drain through relief of urgency 4 Two hundred years later in his analysis of Zhi Zi Dou Chi jia Gan Cao Tang Zou Runan applies Li Dongyuan s theory to argue that within this formula Gan Cao is not exerting supplementing or draining actions but rather that these arise as a consequence of 2 1585 1665 Notably Liu Ruojin was not a doctor but a government official under the Ming When the Ming dynasty was defeated by the Manchus he went into the mountains for the next 30 years investigating materia medica particularly the Ben Cao Gang Mu Grand Materia Medica by Li Shizhen He collected many commentaries and specialised in researching mechanisms of medicinal action 3 B nc o sh g uyu n Y ng Sh t i 1842 Section 7 https ctext org wiki pl if gb res 760296 accessed 21 7 19 4 ibid 28 Vol 16 3 the herb s soothing of Heart fire urgency He writes The Discussion of Cold Damage states If there is anguish in the heart accompanied by taiyang disease Zhi Zi Chi Tang Gardenia and Prepared Soybean Decoction is indicated If there is a deficiency of qi add Gan Cao Yet can we know that this qi deficiency is not a deficiency at all The answer is in the Treatise on the Spleen and Stomach Socalled Heart fire urgency overwhelming the Spleen cannot be understood as a disease of repletion but nor can it be seen as a deficient condition in such cases Gan Cao soothes urgency and in so doing both supplements and drains 5 Reading Liu Ruojin Zou Runan and Li Dongyuan s commentaries it is hard not to be confused by the vagueness of this concept of urgency soothing By what mechanism does Gan Cao soothe Heart fire if not by draining and how does it supplement Spleen qi if not by boosting Furthermore how should these organ based pathologies be understood in the light of the six channel system of the Shang Han Lun The answer to these questions can be found partially in Li Dongyuan s own theoretical commentary on Heart fire He writes When the Spleen and Stomach are deficient the dampness of the earth lingers and accumulates below the navel The Gallbladder being both wind and warmth governs the generation and transformation of the whole body s qi and blood the Small Intestine associated with heat governs the nourishing of yang qi throughout the body Both receive qi from the Stomach and are thus able to upbear and disperse If the Stomach is deficient the hot warm qi of generation and growth of both the Gallbladder and Small Intestine is insufficient and instead lies latent and stagnates with the material blood vessels 5 B nj ng sh zh ng Z u R n n Zhiyuan Bookstore Publishing Co 1997 p 29

feature causing febrile disease wind strike and all manner of issues From a visceral theory standpoint when overactive Heart fire overwhelms Spleen earth this is called middle heat and it manifests with a large surging pulse vexation and stifling 6 In such cases Li Dongyuan recommends using the sweetness of Gan Cao to drain fire heat and supplement original qi of the middle Thus despite Zou s claim that the primary action of Gan Cao is soothing on the contrary when we return to the source we find that Gan Cao s primary actions in Dongyuan s formulation are to supplement and drain Further given that Gan Cao s nature is sweet and neutral it stands to reason that prepared Gan Cao cannot directly drain fire and heat Thus the primary action in this formulation is supplementation which leads indirectly to fire and heat draining How does Gan Cao s supplementing action lead to fire and heat draining To understand this we must dive more deeply into the mechanisms involved in Li Dongyuan s commentary and clarify the physiological and pathological relations between the Small Intestine Heart Stomach and Spleen Liu Ruojin describes Li Dongyuan s Heart fire example like this Though fire is the mother of earth earth is the site of fire s transformation If the Spleen and Stomach are deficient the potential for fire s transformation is abated Fire is the mother of earth when the earth qi is abundant fire is drawn to earth and extinguished within it 7 In a physiological context Heart yang descends into the abdomen transmuting and steaming the fluids of the abdomen and 6 P w i L n L D ngyu n second half https ctext org wiki pl if gb chapter 193010 accessed 21 7 19 7 B nc o sh Li Ru j n Beijing Publishing Co 1997 converting them into qi which upbears and disperses to the exterior The heat of Heart yang and the fluid of the middle and lower burners are consumed in this process of transmutation to make qi and blood Thus fire is drawn to earth and extinguished within it In some theoretical frameworks the site of this transmutation is the Small Intestine For instance T ng R ngch an holds that The Small Intestine is the storehouse of the Heart Heart yang diffuses and distributes down into the Small Intestine and Bladder This is what is known as fire interacting with water This transformative process creates qi which upbears and disperses 8 By contrast in the pathological situation described by Li Dongyuan fluid dampness has accumulated and stagnated in the abdomen as a result of problems arising from the Spleen and Stomach Such accumulations would invariably obstruct the normal flow of qi and blood This leads to three possible problems 1 The descending path of Heart yang is obstructed by the fluid accumulations and reverts upwards upflaming 9 2 Heart yang having descended into the abdomen is unable to disperse the fluids of the lower and middle burners due again to stagnant accumulation The Heart yang thus lies latent or is trapped within the abdomen and manifests as fire and 3 Because most fluids have been lost to stagnant accumulation or to sweat or 8 T ng R ngch an Zh ngx hu t ng y j ng j ngy first half section on five zang under heart https ctext org wiki pl if gb res 505474 accessed 7 21 19 Tang further notes The Small Intestine transforms grain into essence and fluid and distributes it to the Heart where it becomes blood If Heart fire fails to diffuse downward the transformative action of the Small Intestine is impaired 9 This concept is particularly well articulated in the works of Hu ng Yu ny For specific examples see Ch ngsh y oji Changsha Explanation of Medicines For example in his analysis of Huang Lian Coptidis Rhizoma Huang writes Fire hibernates in earth When earth is dry fire downbears and the spirit is clear When earth is damp fire counterflows and the spirit is vexed n William Ceurvels is a licensed acupuncturist and Chinese herbalist in Taiwan where he is finishing a master s thesis analysing the use of Gan Cao in the Shang Han Lun Will s research is on the mechanisms of the classic formulas based on close readings of several Qing and Republic of China era commentators especially Zhang Zhi cong The Lantern 29

feature If blood is deficient then the amount of Heart yang that can be spirited down into the middle and lower burners is reduced diarrhea 10 there is a subsequent lack of fluid available to interact with Heart yang and be dispersed upward as qi and blood This leads to a lack of construction causing stoppage 11 situation Another way to think of this is that blood or construction qi is the conduit of Heart yang 12 If blood is deficient then the amount of Heart yang that can be spirited down into the middle and lower burners is reduced The relatively weakened Heart yang will be less able to penetrate obstructions and disperse accumulated fluids As Heart yang is less able to penetrate and disperse lower middle burner fluids they continue to accumulate and less and less fluid is dispersed as construction qi The diminishing construction qi leads to an even greater diminishment of Heart yang s interpenetrating action on the lower middle burners leading to a greater accumulation of fluid This is a vicious cycle that as we will see Gan Cao is central to resolving Zhang s analysis of Gan Cao How does Gan Cao alleviate the above problems In this case the simple notion of supplementation of middle qi doesn t seem to provide an adequate or relevant answer The notion of soothing is equally puzzling and ineffectual Invariably we must look elsewhere In this case it is helpful to turn to a lesser known and fairly unusual interpretation of Gan Cao s pharmacological action as offered by Zhang Zhicong in his commentary to the Jin Gui Yao L e the Jin Gui Yao L e Zhu Annotations to the Essentials from the Golden Cabinet Zhang argues that the real function of Gan Cao is to more or less pump fluid from the middle burner into the network vessels and 10 The trapped fire of the lower middle burners may also scorch fluids and humours leading to fluid deficiency This would be an example of vigorous fire consumes qi qi consumers the lesser fire Vigorous fire scatters qi while a lesser fire engenders qi 11 12 Huang Yuanyu describes the role of blood like this Blood is yin by nature but contains yang qi it is warm and bears sovereign fire within it This is why for instance in Huang s formula for supplementing yang he notes that special attention should be paid to Liver blood If there is Liver blood deficiency Dang Gui Angelicae Sinensis Radix and He Shou Wu Polygoni multiflori Radix should be added because blood is the mother of the spirit and ethereal soul That is blood bears the spirit yang qi within it 30 Vol 16 3 channels thus achieving the twofold action of a preventing the build up of fluid in the lower and middle burners by pumping and b freeing and nurturing the vessels and channels that were obstructed by the stagnant build up of fluid ostensibly by increasing volume and thereby pressure Zhang thus characterises Gan Cao in a discussion of the formula Fang Ji Huang Qi Tang Stephania and Astralagus Decoction Gan Cao frees from the yellow centre 13 The roots of the living plant bore deep into the earth at different lengths it branches out into thick lateral roots and root hairs just as the network vessels course through the earth abdomen to nourish and free the channels 14 Again in his discussion of Ling Gui Zhu Gan Tang Poria Cinnamon Twig Atractyodes and Licorice Decoction Zhang characterises Gan Cao s action as freeing the network vessels and channels extending from the middle burner 15 In Ren Shen Bai Hu Tang White Tiger Decoction with Ginseng he states simply Gan Cao nourishes the middle qi and frees the vessels In his vivid analysis Zhang Zhicong invites us to consider the licorice plant itself which grows in the extreme dryness of the northern deserts of China and plies deep into the earth rooting for the slightest traces of moisture deftly capturing and containing this moisture and pumping it upward into the stems and branches This process is not unlike the middle burner which captures fluid and diffuses it through the vessels and channels16 13 Zou Runan and Zhang Zhicong both note that Gan Cao has a red exterior and a yellow core Zou Runan particularly emphasized this phenotypic display in his discussion of the herb s pharmaco mechanism Gan Cao has a yellow core and a red skin This is the basis for the herb s fire draining mechanism 14 Zhang Zhicong Zhang Zhicong Yixue Quanshu China Chinese Medicine Publishing Co 1999 p 940 15 16 Zhang Zhicong provides precise physiological descriptions of the movement of fluid from the middle burner in his commentary to the Suwen For instance The Stomach is the sea of blood qi water and grain Fluids are secreted by the Stomach to the exterior of the digestive tract where they are absorbed by the network and grandchild vessels

feature described above as engendering qi While Zhang provides the most detailed description of this process we can see similar ideas appearing in several other scholars commentaries The 20th century jingfang scholar C o Y ngf in a discussion of Hou Po Ma Huang Tang Magnolia Bark and Ephedra Decoction from Jingui Fawei Elaborating on the Subtleties of the Golden Chamber writes about why that formula which otherwise resembles Xiao Qing Long Tang Minor Blue Green Dragon Decoction eliminates the Gui Zhi Cinnamomi Ramulus Bai Shao Paeoniae Radix alba and Gan Cao It is because Shao Yao Gan Cao and Gui Zhi make up the treatment formula Gui Zhi Tang Cinnamon Twig Decoction In the Shang Han Lun this is originally used to support Spleen yang and discharge the interstices of the flesh What Chinese medicine calls Spleen yang is actually what Western medicine calls the pancreas located beneath the anatomical stomach and refers to the process whereby fluid is absorbed from the Small Intestine and diffused it belongs to the middle burner 17 In his description Cao relates that Shao Yao acts to free stagnation from the vessels and Gui Zhi strengthens the Heart propelling fluids outwards By process of elimination the role of Gan Cao in this process is again to absorb fluid from the Small Intestine and guide it into the vessels and channels The Qing dynasty imperial physician and medical scholar Hu ng Yu ny provides a similar if slightly differently worded analysis of Gan Cao Throughout his works we find the common phrase Gan Cao banks up earth and constructs wood qi G n C o p i t r of the membrane and become blood They then move into the great network vessel of the Stomach and on to the great network vessel of the Spleen From thence the blood circulates into the channel passages of the viscera and bowels which extend out into the skin 17 Cao Yingfu in Caoshi Jingui Fawei discussion of Jin Gui chapter 7 under Hou Po Ma Huang Tang Magnolia Bark and Ephedra Decoction https ctext org wiki pl if gb res 149376 accessed 21 7 19 y ng m q 18 In Huang s analysis wood qi mostly refers to the construction qi of the vessels and channels which is why he uses the word construct to describe the action of Gan Cao Again the action of Gan Cao is seen to be nourishment and freeing of the vessels from the middle burner Thus in all three of these Qing dynasty scholars accounts Gan Cao acts by nourishing and freeing the vessels from the yellow centre which is to say it pumps fluid from the middle burner into the vessels and channels leading away from it It is easy to see how by diverting fluid from the middle burner into the vessels and channels Gan Cao thereby nourishes the vessels and channels The notion of diversion freeing the flow of the vessels and channels is less obvious but can be further substantiated with examples from Chinese and Western medicine alike From the perspective of Western medicine Gan Cao has been shown to increase blood cortisol levels Cortisol in turn promotes the reuptake of water from the small intestine and kidneys into the blood stream The increased blood volume causes a subsequent increase in blood pressure and capillary perfusion pressure which provides the energy required to overcome blood flow resistances 19 Put simply Gan Cao increases blood pressure which allows for improved blood flow across areas of resistance especially in capillaries The concept of increased volume leading to increased pressure was also recognised It is easy to see how by diverting fluid from the middle burner into the vessels and channels Gan Cao thereby nourishes the vessels and channels 18 Huang Yuanyu Shanghan Xuanjie chapter 17 http www zysj com cn lilunshuji shanghanxuanjie index html accessed 21 7 19 He says 19 a For information on the relationship between licorice and cortisol Busty Anthoni The Mechanism for Licorice Glycyrrhiza glabra Induced Swelling and Edema Evidence Based Medicine Consult August 2015 https www ebmconsult com articles licoricegly cyrrhizaglabraedemaswellingmechanismsideeffect b Blood pressure and perfusion pressure Capillary perfusion pressure is a primary determinant of FCD The perfusion pressure provides the energy required to overcome the blood flow resistances associated with vessel diameter hydrodynamic effects at vessel bifurcations RBC deformability capillary lumen obstructions and viscosity Capillary perfusion pressure is determined by central blood pressure or MAP J Wegner in Minimized Cardiopulmonary Bypass Techniques and Technologies 2012 The Lantern 31

feature Chinese and Western medical theory support the notion that by increasing the volume or amount of blood moving through the channels and vessels the force of bloodflow increases allowing for smoother less obstructed circulation 32 Vol 16 3 by Chinese medical scholars Qing dynasty medical scholar B o Hu in his theoretical tome Y y Xi oc o writes Naturally if the original volume and thus force blood pressure is increased the force in all of the divided parts will commensurately increase Ming dynasty medical scholar Mi o X y ng summarised this concept eloquently in his discussion of why the properties of making the channels flow freely and disinhibiting blood and qi are attributed to Gan Cao in the Mingyi Bielu Miscellaneous Records of Famous Physicians Sweetness enters the Spleen and engenders blood If there is blood deficiency then the vessels will not flow freely by engendering blood the vessels will free of themselves 21 This concept correlates precisely with the previously mentioned lack of construction causing stoppage Thus Chinese and Western medical theory support the notion that by increasing the volume or amount of blood moving through the channels and vessels the force of bloodflow increases allowing for smoother less obstructed circulation In the above we have given a comprehensive account of the first aspect of Zhang Zhicong s special analysis of Gan Cao We have detailed Zhang s description of how Gan Cao pumps liquid from the middle burner into the vessels and channels thereby nourishing and freeing the channels The second aspect of Zhang s account is intimately related to the first in the process of pumping liquid from the middle and lower burners22 to the vessels Gan Cao prevents the build up and stagnation of what he calls yin water or water evil therein Typically in instances where Zhang refers to this second action Gan Cao is mentioned in connection with Bai Shao Paeoniae Radix alba For instance in his commentary of Xiao Qing Long jia Shi Gao Tang Minor Blue Green Dragon Decoction plus Gypsum Zhang holds Shao Yao is paired with Gan Cao to transform earth qi and protect against water evil 23 Again in Si Ni San Counter flow Cold Powder Zhang writes Shao Yao and Gan Cao jia ji combine and transform earth 24 to restrain yin water Throughout his commentary Zhang holds that the function of Shao Yao in this combination is to transform stasis and course the vessels Combined with Gan Cao s flow increasing pressure increasing powers the two have the additive effect of flushing the vessels of resistance Shao Yao with bitter draining and Gan Cao with supplementary freeing The vessels are the primary means by which fluids are dispersed from the middle burner as detailed in footnote 16 By flushing the vessels Gan Cao and Shao Yao ensure that the route of dispersion for middle burner fluids remains patent Additionally Gan Cao actively pumps fluids from the middle and lower burners These two actions work synergistically to prevent the accumulation of yin water in the lower and middle burners This is what is meant by transforming 20 Yiyi Xiaocao Draft Notes on Medicine and Physicians B o Hu Juan One https ctext org wiki pl if gb chapter 319036 accessed 7 21 19 21 Miao Xiyong s Shennong Bencao Jingshu Commentary on the Divine Husbandman s Classic of Materia Medica Juan Six https ctext org wiki pl if gb chapter 259760 under accessed 28 7 19 22 Some may question the notion that Gan Cao pumps fluids from the lower burner as well as the middle burner The author would advise scholars with such misgivings to see Zhang Zhicong s analysis of Tao He Cheng Qi Tang Peach Pit Decoction to Order the Qi in which he describes how Gan Cao is paired with Gui Zhi Cinnamomi Ramulus to out thrust taiyang qi Surely no one would argue that Tao He Cheng Qi Tang is a formula pattern of anything but the lower burner 23 Zhang Zhicong Zhang Zhicong Yixue Quanshu China Chinese Medicine Publishing Co 1999 p 953 24 Water flows rapidly through narrow parts of rivers and slowly through the wider parts Why is it then that blood flows rapidly through large vessels and slowly through narrow vessels Indeed water flows rapidly through narrow rivers but if the river breaks off into rivulets and streams narrow ports and shallow channels then the discharge into each break will be a slow weak trickle Would this not be even more the case for a large channel splitting off into thousands of vessels When force is divided the force of the subsequent parts is weakened this accords with logic 20

feature earth to restrain yin water References to Gan Cao s ability to thicken earth virtue or bank up earth to dam water are poetic ways of describing the herb s ability to pump fluid and ensure the patency of the routes of dispersion for fluids in the middle and lower burners To review we have established in the above that the action of Gan Cao is to pump fluid from the middle burner into the network vessels and channels thus achieving the twofold action of first freeing and nourishing the vessels and channels that were obstructed by stagnant fluids and then preventing the build up of fluids in the lower and middle burners Having established a precise mechanism of action for Gan Cao we can now return to the pathologies mentioned above As previously detailed in Li Dongyuan s description of Heart fire overwhelming the Spleen the primary etiology concerns damp fluid accumulation in the middle and lower burners leading to one of three outcomes n Obstructing the descending path of Heart fire leading to upflaming n Obstructing the vessels or routes of dispersion of Heart fire and fluid or n Contributing to a lack of available fluid to interact with Heart fire resulting in a lack of construction causing stoppage situation lack of conduit for Heart yang leading to reduced transmission of Heart yang to middle and lower burners which also impairs dispersion The vessels and channels are the primary means of dispersion for Heart yang and fluid as they transform into qi and blood in the middle and lower burners Stagnation of any kind prevents this dispersion Cao Yingfu describes the pathology like this Zhang Zhicong describes the process like this The channel passages are the root of efflux for qi and blood Thus the saying that water enters the channels and becomes blood Blood sweat and urine are all produced from the liquid that enters the Stomach Any stagnation will lead to the production of rheum Construction defense qi and blood all also arise from the grain and water essence entering the Stomach If water and fluid are not properly distributed they collect and become phlegm This leads to stagnation in the network vessels and the interstices 25 Gan Cao actively pumps middle and lower burner fluid into the vessels and channels simultaneously producing three results n Reducing accumulation and stagnation of water evil allowing for Heart yang to descend and interpenetrate the middle and lower burners unobstructed n Allowing for fluids to be dispersed from the middle and lower burners unobstructed for the same reason that water evil is not depressing construction qi or n By nourishing construction qi the amount of Heart yang conduited to the middle and lower burnes increases or alternatively stated the force of blood construction qi moving through the vessels and channels increases thereby flushing the depressed or obstructed areas from within Because Heart yang and fluids are efficiently dispersed from the lower and middle burners there is no subsequent build up of yang heat manifesting as Heart fire Again this allows for efficient dispersion of fluid and Heart yang Because Heart yang and fluids are efficiently dispersed from the lower and middle burners there is no subsequent build up of yang heat manifesting as Heart fire To use Li Dongyuan s terminology the heat of the lower and middle burners originating from descending Heart fire is able to receive the qi of the Stomach fluids collecting in the lower and middle burner and upbear and disperse Li Dong yuan clarifies this idea stating If the qi of the abdomen does not rotate transition from downbearing to upbearing increase the dose of Gan Cao by half 26 T ng R ngchu n characterises Gan Cao s action thus In the process of engendering earth fire is drained Gan Cao guides fire to engender earth thereby draining fire The often overlooked key to this process is the dual and mutually engendering actions of transforming earth and protecting against water evil and freeing and nourishing the 25 The Collected Works of Zhang Zhicong Concise Manual of the Golden Chamber Juan 3 26 Li Dongyuan Piwei Lun Juan One https ctext org wiki pl if gb chapter 193010 accessed 22 7 19 The Lantern 33

feature The addition of Gan Cao allows for Heart yang and construction qi to flush through the depressed areas of circulation with increased force channels and vessels as characterised by Zhang Zhicong Zhang s theory and Shang Han Lun As Zou Runan intuitively noted the same etiology that marks Li Dongyuan s Heart fire pathology can be applied to an analysis of Zhi Zi Dou Chi jia Gan Cao Tang Gardenia Licorice and Prepared Soybean Decoction with some subtle differences As in Li s example the main pathology consists of Heart yang being unable to descend interpenetrate and thereby disperse the fluids because Spleen and Stomach deficiency has led to stagnations of fluid rheum and phlegm that depress circulation through the middle and lower burners Unable to descend into the middle and lower burners Heart fire refracts and upflames upon itself leading to heart anguish Huang Yuanyu describes the pathology Sweating and precipitation cause middle deficiency Stomach earth counterflows turbid qi stagnates Sovereign fire cannot descend and so the Heart palace is plagued by vexing heat 27 Dou Chi Sojae Semen is indicated for turbid qi ie the rheum and phlegm that has built up in the lower and middle burners and obstructs the interpenetration and dispersion of Heart yang Thus Huang Yuanyu characterises the herb s action as eliminating turbid stagnation and undoing obstruction clearing stale build ups and quieting the spirit s abode 28 Zou Runan states Where yin obstructions exist yang cannot pass through Clear yin obstructions and yang will pass through of itself this is Dou Chi s action 29 Zhi Zi Gardeniae Fructus is also indicated for turbid qi but has the additional action of directly clearing Heart fire Thus Huang Yuanyu states simply Zhi Zi clears turbid stagnation and drains vexing heat 30 Taken together these two medicinals clear the stagnations caused by temporary Spleen and Stomach deficiency allowing Heart fire to interpenetrate the lower and middleburners dispersing fluid and importantly creating 27 Changsha Yaojie Huang Yuanyu Juan One https ctext org wiki pl if gb chapter 556308 accessed 22 7 19 28 ibid 29 Z u R n n B nj ng sh zh ng Zhiyuan Bookstore Publishing Co 1997 p 265 30 op cit 34 Vol 16 3 more blood which upbears and nourishes quells Heart fire If sweating and precipitation lead to a more substantial loss of fluid then the overall volume and force of blood moving through the middle and lower burners and amount of Heart yang conduited is diminished resulting in a lack of construction leading to stagnation pathology The addition of Gan Cao allows for Heart yang and construction qi to flush through the depressed areas of circulation with increased force promoting interpenetration dispersion and upbearing The increase in construction qi blood also importantly nourishes and quells Heart fire31 Finally insofar as Gan Cao pumps fluid from the middle and lower burners it also prevents any additional build up of fluid that may initiate the vicious cycle described above Just as in the Li Dongyuan example the use of Gan Cao in Zhi Zi Dou Chi jia Gan Cao Tang embodies the notion of In the process of engendering earth fire is drained Gan Cao guides fire to engender earth thereby draining fire Perhaps an even more dramatic example of Gan Cao s precise pathomechanism can be found in the formula Gan Cao Tang Licorice Root Decoction Traditionally insofar as Gan Cao Tang calls for raw Gan Cao most commentators concluded that the primary action of Gan Cao in Gan Cao Tang was to directly drain Heart fire However a minority of authors including Zou Runan Zhang Zhicong Tang Rongchuan and Chen Xiuyuan 32 focused on the disease etiology of the formula pattern and came to different conclusions As in the case of Zhi Zi Dou Chi jia Gan Cao Tang Zou Runan correctly intuited that Gan Cao drains fire in a much different way than bitter cold herbs but failed to provide a precise mechanism He writes The lesser yin channel passes through the throat The statement In the second or 31 Tang Rongchuan writes Only when the Heart receives yin essence does the spirit shine limpid and tranquil When there is Heart blood deficiency the spirit is vexed Limpid and tranquil is a translation of which like the word limpid communicates the image of a clear undisturbed light as reflected off or penetrating through a tranquil water 32 Notably these four authors all lived in the coastal area of Jiangsu The latter three authors were members of the Qiantang school Lu Zhiyi a major influence of Zou Runan s founded this school

feature third day of lesser yin disease there is throat pain is an obvious example of an urgent disease with lesser yin evil heat travelling along its direct channel to affect the throat Gan Cao soothes urgency providing rapid relief This is a case of supplementing via soothing which indirectly drains heat 33 Zou indeed seems to grasp the outlines of the true pathomechanism of Gan Cao Tang He intuits that the true action of Gan Cao in the formula is a kind of supplementation as opposed to direct draining but because he fails to address the precise disease etiology of the formula pattern his characterisation betrays a certain vagueness and incompleteness To arrive at a precise definition of Gan Cao s action we must first understand the disease etiology The Treatise on Cold Damage Diseases describes the general etiology like this The patient s pulse is tight in both the yin and yang positions and yet there is sweating This indicates yang collapse and lesser yin disease According to theory there should be throat pain vomiting and diarrhea Huang Yuanyu expands further on this etiology by noting In lesser yin disease water is replete and the earth is damp as a result the two fires Heart and ministerial counterflow 34 In this formula pattern there is underlying yang deficiency that is exacerbated by contracting external evil Heart yang is further depleted by sweating weakening its ability to interpenetrate and disperse fluids in the middle and lower burners leading to an accumulation of fluid which triggers vomiting and diarrhea As fluid accumulates Heart yang is less and less capable of interpenetration and eventually counterflows manifesting as flaring Heart fire producing throat pain As in previous examples the role of Gan Cao is to pump fluids from the lower and middle burners into the network vessels and nourish and free the channels thereby indirectly augmenting Heart yang Tang Rongchuan says In the process 33 Op cit p 29 34 Huang Yuanyu Shanghan Xuanjie Juan 11 http www zysj com cn lilunshuji shanghanxuanjie index html accessed 22 7 19 of engendering earth fire is drained Gan Cao guides fire to engender earth thereby draining fire Gan Cao slowly guides fire downwards draining as it engenders and thus fire is eliminated 35 By pumping fluids from the lower and middle burners into the vessels and channels Gan Cao clears obstructions while augmenting Heart yang so that Heart yang can successfully interpenetrate the lower and middle burners and disperse fluids Successful interpenetration means that Heart yang will not counterflow and produce upflaming Heart fire Zhang Zhicong emphasises the flipside of this process in which Gan Cao nourishes construction qi which in turn enriches Heart blood and quells Heart fire Throat pain the Heart channel passes through the throat The qi of the yin channels is unable to enrich the sovereign fire this is the source of the throat pain Licorice supplements the Stomach to nourish the channels 36 Thus just as in the case of Zhi Zi Dou Chi jia Gan Cao Tang Gan Cao drains Heart fire in two ways First it removes any obstructions that may inhibit Heart yang in its path of descent and dispersion through the abdomen thus eliminating the possibility of counterflow and upflaming Second in the process of nourishing the vessels and channels Gan Cao thus enriches Heart blood and yin which quells Heart fire This article describes a novel pharmacomechanism of Gan Cao based upon the little known commentary to the Essentials of the Golden Chamber by Zhang Zhicong In the above we have shown how this mechanism can be applied to two formulas from the Treatise on Cold Damage Diseases In reality the applications of this mechanism are truly endless For instance the action of Gan Cao in Shao Yao Gan Cao Tang Peony and Licorice Decoction Gui Zhi Gan Cao Tang Cinnamon Twig and Licorice Decoction and Feng Sui Dan Marrow Retaining Elixir is similar to the mechanism described above Throat pain the Heart channel passes through the throat The qi of the yin channels is unable to enrich the sovereign fire this is the source of the throat pain 35 Tang Rongchuan Shanghan Lun Qianzhu Buzheng Xueyuan Publishing Company 2012 p 317 36 Zhang Zhicong Shanghan Lun Zongyin Section Five https ctext org wiki pl if gb chapter 275950 accessed 22 7 19 The Lantern 35