Effects of copper chloride on the slow response action potential and oscillatory afterpotential induced by ouabaini

The effects of copper chloride (CuCl2) on slow response action potentials were studied in vitro by means of an intracellular microelectrode. CuC12 10 vmol/L reduced the amplitude, the slope of phase 4 and shortened the duration of the action potential of the rabbit sinoatrial nodes. The effects of CuCl2 100 vmol/L on the slow response action potential of guinea pig papillary muscles in KCl-rich (25 mmol/L) solution were similar to those on rabbit sinoatrial nodes. CuCl2 100 vmol/L immediately abolished the spontaneous elecrical activity and inhibited the oscillatory afterpotential of guinea pig papillary muscles which had been induced by ouabain. The results indicate that Cu2+ may suppress the slow inward current of myocardial muscles.