Zheng G H, Chen Z L, Jiang J H
Department of Physiology, Guang-dong College of Pharmacy, Guangzhou, China.
Zhongguo Yao Li Xue Bao. 1998 Sep;19(5):497-500.
To study the effects of O-(4-ethoxyl-butyl)-berbamine (EBB) on isolated frog heart.
The isolated frog hearts were prepared with Straub's method; heart contractions were recorded using LMS-2A recorder by tonotransducer.
EBB 1-100 mumol.L-1 caused concentration-dependent increase in systolic and diastolic activities, but did not alter the heart rate. EBB 250-500 mumol.L-1 slowed the heart beats and caused ventricular asystole. Cimetidine 10 mumol.L-1 or prazosin 100 mumol.L-1 did not inhibit the positive inotropic action of EBB. Whereas verapamil 0.01 mumol.L-1 antagonized the positive inotropic action of EBB. EBB enhanced positive inotropic action of CaCl2. The action of EBB was slower but longer than caffeine or isoproterenol. At room temperature (21.0 +/- 0.5) degree C, however, the onset of oubain was slower, but the duration of its peak action was longer, than EBB.
The positive inotropic action of EBB was, at least partially, via promoting the inward current of [Ca2+]o, rather than increasing the intracellular Ca2+ release.
