急性心肌缺氧时某些负性变导及变时性心律失常与内生性腺苷的关系

豚鼠64只,全麻下经气管插管正压呼吸,吸入不同氧含量的缺氧混合气体,观察Ⅱ导心电图,测定心肌腺苷水平及血p₀₂、K⁺和pH值。目的在于通过对缺氧程度、心电变化、腺苷水平3变量的同步定量研究来探索急性心肌缺氧时负性变导及变时性心律失常与内生性腺苷的关系。结果表明:(1)心肌缺氧所致的心律改变与内生性腺苷增高二者关系极为密切;(2)氨茶碱可阻断心肌缺氧时发生的负性变导及变时性心律改变,提示腺苷水平与心律变化之间存在着一定的因果关系;(3)迷走神经兴奋,血K⁺、血pH变化在短期缺氧时不是窦房结及房室结功能抑制的主要原因。

The Relationship between Dromotropic and Chronotropic Arrhythmias and Endogenous Adenosine during Myocardial Hypoxia

The experiments were performed on 64 guinea pigs. Artificial respiration was carried out under general anesthesia. Before and after graded hypoxia lead Ⅱ electrocardiogram was recorded and myocardial adenosine level, blood K⁺, pH and po₂ Were measured to explore the relationship between dromotropic and chronotropic arrhythmias and endogenous adenosine during hypoxia by synchronous quantitative study of three variables-degree of poxemia, changes in electrocardiogram and myocardial level of adenosine. Experimental results disclosed that (1) A close relation existed between the changes in cardiac rhythm and endogenous myocardial adenosine caused by hypoxia; (2) aminophylliue antagonized the negative dromotropic and chronotripic arrhythmias and there existed a cause and effect relation between the endogenous myocardial adenosine and such hypoxia arrhythmias; (3) Vagal drive, K⁺ and pH had little if any bearing on the functional inhibition of the S-A and A-V nodes during the period of short-term hypoxia encountered in such cases.