Abstract: Cytosolic free Ca²⁺─Ca²⁺i was measured in dissociated cerebral cells isolatedfrom fetal rats using the fluorescent indicater Fura-2.Increases inCa²⁺i occurred rapidly followingexposure of the cells to 50 mmol·L^-1 KCl,10^-7 mol·L^-1 Bay K 8644 and 200 umol·L^-1 glu-tamate(Glu ). Ca²⁺i elevation produced by K+ -depolarization was blocked completely by pretreat-ment with tetrandrine(Tet)of various concentrations(10^-9～10^-7 mol·L^-1,final).Tet showedsignificant inhibitory effect onCa²⁺i increases stimufated by Glu in concentration-dependentmanner.With Tet 10^-7 mol·L^-1,Bay K 8644-induced increases inCa²⁺i were reduced-markedly.These results indicate that Tet can block the increases in Ca²⁺i in fetal rat cerebral cellsinduced by Ca²⁺ agonists,suggesting that this drug may have a protective effect on cerebral cellinJury.