肌苷对缺氧心肌跨膜电位和收缩强度的影响

本工作在正常和缺氧情况下,观察肌苷对豚鼠心室乳头肌跨膜电位和收缩强度的影响。结果表明肌苷使正常心肌细胞动作电位时间(APD_(10)、APD_(50)延长。在缺氧心肌,肌苷使细胞静息电位增大,动作电位去极化幅度增高,零期最大去极化速度加快和动作电位时间延长。肌苷增加正常心肌收缩力,使缺氧心肌收缩的衰减显著缓和,亦即使收缩功能改善,且表现剂量-依从性。肌苷对心肌细胞跨膜电位的影响提示它很可能有抗心律失常作用,特别是在缺氧心脏。肌苷对离休乳头肌收缩的影响,证明其对心肌有直接的强心作用。

EFFECTS OF INOSINE ON THE TRANSMEMBRANE POTENTIAL AND CONTRACTILITY OF HYPOXIC CARDIAC MUSCLE

Effects of inosine on transmembrane potential and contractility were observedin guinea pig papillary muscle. The results indicated that in normal, ventri-cular muscle, inosine prolonged the action potential duration (APD_(10), APD_(50)),especially at the early phase of repolarization. In the hypoxic muscle, it caused anincrease in resting potential, action potential amplitude, maximum upstroke velocityof 0 phase depolarization and prolongation of APD. Inosine increased the contracti-lity of normal myocardium and retarded the decline of contractility following hypo-xia, which showed in a dose-dependent manner. The effects of inosine on the trans-membrane potential of hypoxic cardiac muscle suggested that it might have ananti-arrhythmic action, especially in the hypoxic heart. The influence of inosineon the contractility of isolated papillary muscle indicated that it had a directpositive inotropic action on the myocardium.