Effects of berbamine on ATP-induced [Ca2+](i) mobilization in cultured vascular smooth muscle cells and cardiomyocytes

AIM: To study the effects of berbamine (Ber) on [Ca2+](i) homeostasis induc ed by adenosine triphosphate (ATP) in vascular smooth muscle cells (VSMC) o f rabbits and cardiomyocytes of rats. METHODS: Both cell types were culture d and loaded with Fura 3-AM. [ Ca2+](i) was measured by fluorescent intensi ty (FI) in each cell with confocal microscopy. RESULTS: (1) ATP 30 mu mol . L-1 elevated [Ca2+](i) in VSMC and cardiomyocytes, FI values reached 660 /- 258 and 1058 +/- 252 from 250 +/- 84 and 218 +/- 76 at 19 s +/-5 s and 1 1.8 s +/- 2.4 s, but FI in nucleus was not changed in VSMC. (2) Ber 30 mu m ol . L-1 did not affect the resting FI in both cell types, but prolonged th e time to peak (P < 0.01) and reduced the FI elevated by ATP (P < 0.01), bu t not completely inhibited even at 100 mu mol . L-1. (3) In D-Hanks' soluti on or in the presence of egtazic acid (EGTA) 3 mmol . L-1, the inhibitory e ffect of Ber was not seen (P >0.05). (4) All effects of Ber on ATP-induced [Ca2+](i) mobilization were similar to those of Ver 10 mu mol . L-1 CONCLUS ION: In VSMC and cardiomyocytes, ATP-induced Ca2+ influx was inhibited by B er and Ver, while the Ca2+ release was not.