ABSTRACT
Objective To study the relationship between ? 1-aderenergic receptor (? 1-AR) and cardiac function in hypoxic newborn guinea-pig myocardia undergoing ischemic reperfusion, and the effects of St. Thomas Hospital cardioplegic solution Ⅱ (STS) and cold blood cardioplegia (CBC) on the ? 1-AR and cardiac function. Methods Normobaric hypoxic guenia-pig model and isolated perfused working heart preparation were established. Cardiac functions were recorded by a multichannel biologic signal analyzer. Myocardial ? 1-AR density (B max ) and affinity (K d) were investigated by radial ligand binding. Results Significant decrease of B max was found in hypoxic newborn guinea-pig myocardia suffering from hypothermic (20 ℃)-ishemic reperfusion (P0.05). Conclusion The impairment of cardiac function in hypoxic newborn guinea-pig undergoing myocardial ischemic reperfusion might be associated with the decline of B max , but not with K d. Different effects of STS and CBC on cardiac function may result from their different influences on B max .