Inhibition of ATPases by Cleistocalyx operculatus. A possible mechanism for the cardiotonic actions of the herb.
The water extract of the buds of Cleistocalyx operculatus, Roxb. (CO), a herb commonly used as an ingredient for tonic drinks in southern China, was shown to increase the contractility and decrease the frequency of contraction in an isolated rat heart perfusion system. CO was found to inhibit Na+/K(+)-ATPase activities in rat heart sarcolemma, as well as in a purified enzyme from porcine cerebral cortex. CO also inhibited Ca(2+)-dependent ATPase in mouse heart homogenate and in mouse heart sarcoplasmic reticulum at a similar dose. These enzyme inhibitory actions provide a possible explanation for the positive inotropic and negative chronotropic actions of CO on the perfused rat heart. This study suggests the presence of ATPase inhibitory compounds in CO with specificities different from that of ouabain.
Woo
Anthony Y H
AY
School of Chinese Medicine, Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China.
Waye
Mary M Y
MM
Kwan
H S
HS
Chan
Melanie C Y
MC
Chau
C F
CF
Cheng
Christopher H K
CH
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009200:Myocardial Contraction / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012508:Sarcolemma / Q000187:drug effects / Q000201:enzymology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
D002316:Cardiotonic Agents; D004365:Drugs, Chinese Herbal; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium