Pharmacological study of a traditional Chinese medicine: effect of bezoar bovis on the irregular beating pattern of cultured mouse myocardial cells.

The water-extract from "Bezoar bovis", a drug used in Chinese traditional medicine, was examined for its ability to alter the beating pattern of spontaneously contracting cultured embryonic mouse myocardial cells following changes in extracellular calcium (Ca2+). Incubation of the cells with medium containing low Ca2+ concentration (0.4 mM) caused the number of beating cells and beating rate to decrease and the number of arrhythmic cells to increase. By contrast, the number of beating cells decreased while beating rate and the number of arrhythmic cells increased at high Ca2+ (20 mM). Addition of Bezoar bovis extract to the medium attenuated the response to varying Ca2+ concentration. One of the major constituents of Bezoar bovis extract, taurine, was effective in protecting against the abnormal beating pattern induced by high Ca2+. Since beta-alanine, an inhibitor of taurine transport, antagonized the protective effects of both Bezoar bovis and taurine, it is likely that the effect of Bezoar bovis is partially mediated by taurine.