Pueraria: an Herbal Beta-blocker?

Pueraria (葛根) is known in Chinese Medicine to have the following broad functions:

  • facilitate perspiration to bring down fever e.g. for fever and chills with an added symptom of a a stiff nape
  • Facilitate ‘flaring’ of skin poisons: usually to bring the ‘poison’ in skin diseases to the surface
  • Regenerate fluids and quench thirst: for treating 消渴证, a close cousin of what is labelled as diabetes these days
  • Raise Yang to stem diarrhea : for certain kinds of diarrhea (the damp-heat type)

Beta-blocker Function:

One of the actions of Pueraria is as a beta-receptor antagonist. This means it blocks beta-receptors from receiving signals it normally can receive, and because these signals usually serve a purpose, that purpose can no longer be manifest.

Take for example Propranolol (普萘洛尔 aka 心得安), a well-known beta-blocker used for arrhythmia, angina pectoris, high blood pressure, as well as hyperthyroidism. Its action on beat-receptors is non-selective i.e. it blocks both beta-1 and beta-2 receptors. Hence, hypertensive folks also suffering from asthma should not use it lest the beta-2 receptors of their bronchial smooth muscles are blocked as well, making acute and existing situation.

Two well known beta-receptors are beta-1 and beta-2. There is also beta-3. Each type of receptor is known to congregate more in certain places.

  • Beta-1 receptors congregate in huge quantity on the membrane of cardiac muscle cells. When signals come in the form of norepinephrine from the nerve endings of the sympathetic nervous system, the heart beats faster and pumps harder. Beta-1 blockers will prevent this from happening, and is useful if you have at hand an overactive heart.
  • beta-1 receptors also congregate near the glomerulus of the kidneys, passing on the signal to produce more renin, which activates the RAAS system. Blocking these receptors will cause a fall in renin production causing a string of events that reduce blood pressure and reduce urine production.
  • Beta-2 receptors congregate on bronchial smooth muscle (支气管平滑肌),coronary artery (冠状动脉) and skeletal muscle blood vessels (骨骼肌血管). Without blockers at hand, signals will cause dilation in these areas. However, beta-2 blockers may pose a risk to those with a history of asthma. For these people, their bronchial smooth muscles may constrict easily, causing another asthma attack.
  • Beta-3 receptors hang out in fat cells. To my knowledge, there is to date no known pharmaceutical drug that can facilitate or block these receptors.

Beta-blockers may slow down the breakdown of lipids. it can also help diabetics using insulin to lengthen the time taken for blood glucose levels to rise again after the insulin has brought the levels down.

Pueraria’s action on the cardiovasculature:

Can Pueraria’s properties as described by Chinese Medicine be explained by its various actions on the cardiovasculature? My speculative thoughts on this:

  • For fever and chills with an added symptom of a a stiff nape, a better flowing cardiovasculature may facilitate both perspiration and the work of our immune system
  • For skin diseases, promoting blood flow can increase metabolism and hasten the process of detoxification
  • For conditions of thirst, we could think of pueraria as an inhibitor of renin production, which then reduces the amount of urine passed out.
  • For damp-heat type diarrhea, the idea of hastening the process of detoxification can once again be used to explain how Pueraria promotes blood flow and hastens detox.