EFFECTS OF PRAERUPTORINE-C ON THE INTRACELLULAR FREE CALCIUM IN NORMAL AND HYPERTROPHIED RAT VENTRICULAR MYOCYTES

AIM: To study the intracellular free calcium ([Ca2+](i)) in normal and hypertrophic left ventricular myocytes isolated from adult rat hearts and the effects of praeruptorine C (Pra-C) on them. METHODS: [Ca2+](i ) of single myocyte was measured with Fura 2-AM. RESULTS: The resting [Ca2+](i) was 87 +/- 4 nmol.L-1 in normal left ventricular myocytes, 1 23 +/- 7 nmol.L-1 in hypertrophied myocytes. After exposure to KCl (20 , 40, and 60 mmol.L-1), the [Ca2+](i) were increased by 66 %, 141 %, a nd 268 % in normal myocytes, and 77 %, 185 %, and 243 % in hypertrophi c myocytes, respectively. Pra-C (1, 10, and 100 mu mol.L-1) concentrat ion-dependently inhibited the [Ca2+](i) elevation caused by KCl (35 mm ol.L-1) or norepinephrine (20 mu mol.L-1) in both normal and hypertrop hied myocytes. All of the effects of Pra-C were similar to that of nif edipine. CONCLUSION: [Ca2+](i) of hypertrophied myocytes was higher th an that of normal ones and Pra-C decrease the [Ca2+](i) elevation in l eft ventricular myocytes resulted from its calcium channel blockade.