Abstract: The effects of 2-[p-(Dimethylamino)styryl] pyridine methiodide (DSPM) on slow response action potential (SRAP) and slow inward current (Isi) of guinea pig papillary muscles were studied by intracellular microelectrodes and voltage clamp techniques. The APA and Vmax of SRAP induced by high K⁺ were decreased after 50 min of perfusion with DSPM solution. Isi was suppressed from a peak value of 8.8±1.6 μA to 5.7±1.8 μA, The results indicated that DSPM has a selective blocking effect on calcium channel.

Key words: p-(Dimethylamino)styryl] pyridine methiodide(DSPM), Verapamil, Calcium chloride, Papillary muscle, Calcium channel, Voltage clamp, Action potential