Perfusion with Ca2+-free K-H solution completely abolished the effects of SNP(10-4 mol/L) on AV node cell.

• （4）为进一步研究Ca2+的作用，给予无钙K-H液灌流房室结标本，观察到SNP（10-4 mol/L）对房室结细胞的动作电位各参数无影响，APA，Vmax，VDD和RSF均无明显变化；