[Protective effects of tetrandrine on calcium paradox in isolated rat heart].

The protective effects of tetrandrine (Tet) on calcium paradox in isolated Langendorff's heart in rats were investigated. Tet was shown to reduce the release of lactate dehydrogenase (LDH) and protein from myocardial tissues and the loss of K+, Mg2+ and accumulation of Ca2+, Na+ in myocardial tissues during calcium paradox in a concentration-dependent manner. Decrease of Fe and Zn and increase of Cu in myocardial tissues were observed in calcium paradox and Tet 27 mumol/L was found to inhibit the decrease of Fe and Zn. In addition, Tet was also found to inhibit the decrease of Ca2+ and the increase of Na+ in myocardial tissues during calcium-free perfusion. These results indicate that Tet can protect the myocardium against calcium paradox by stabilizing cellular membrane and inhibiting the influx of Ca2+.