[Effects of tetrandrine on cytosolic free calcium in fetal rat cerebral cells].

Cytosolic free Ca(2+)-[Ca2+]i was measured in dissociated cerebral cells isolated from fetal rats using the fluorescent indicator Fura-2. Increases in [Ca2+]i occurred rapidly following exposure of the cells to 50 mmol.L-1 KCl, 10(-7) mol.L-1 Bay K 8644 and 200 mumol.L-1 glutamate (Glu). [Ca2+]i elevation produced by K(+)-depolarization was blocked completely by pretreatment with tetrandrine (Tet) of various concentrations (10(-9) - 10(-7) mol.L-1, final). Tet showed significant inhibitory effect on [Ca2+]i increases stimulated by Glu in concentration-dependent manner. With Tet 10(-7) mol.L-1, Bay K 8644-induced increases in [Ca2+]i were reduced markedly. These results indicate that Tet can block the increases in [Ca2+]i in fetal rat cerebral cells induced by Ca2+ agonists, suggesting that this drug may have a protective effect on cerebral cell injury.