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 induced by adenosine triphosphate (ATP) in vascular smooth muscle cells (VSMC) of rabbits and cardiomyocytes of rats. METHODS: Both cell types were cultured and loaded with Fura 3-AM. [ Ca2+](i) was measured by fluorescent intensity (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 11.8 s +/- 2.4 s, but FI in nucleus was not changed in VSMC. (2) Ber 30 mu mol . L-1 did not affect the resting FI in both cell types, but prolonged the time to peak (P < 0.01) and reduced the FI elevated by ATP (P < 0.01), but not completely inhibited even at 100 mu mol . L-1. (3) In D-Hanks' solution or in the presence of egtazic acid (EGTA) 3 mmol . L-1, the inhibitory effect 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 CONCLUSION: In VSMC and cardiomyocytes, ATP-induced Ca2+ influx was inhibited by Ber and Ver, while the Ca2+ release was not.