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用离体兔心灌流、窦房结细胞动作电位记录、膜片钳实验和放射免疫分析细胞内cAMP含量等方法,研究不同周龄组兔心自律性变慢的心脏内源性因素。实验结果提示,离体心脏和窦房结标本在没有神经体液因素影响的情况下也有随周龄增长而自律性变慢的现象。进一步的实验提示,这可能是由于窦房结细胞内cAMP含量下降,使起搏离子流If的阈电位向负方向移位,造成窦房结细胞4期自动除极速率降低,最后导致心率变慢。上述结果表明,成长过程中的心率变慢,除有神经体液因素影响外,窦房结细胞本身自律性的改变也起了一定作用。
In vitro rabbit cardiac perfusion, sinoatrial cell action potential recording, patch clamp experiments and radioimmunoassay of intracellular cAMP levels and other methods to study the different weeks age group of rabbit cardiac autonomic slow cardiac endogenous factors. Experimental results suggest that isolated hearts and sinoatrial specimens in the absence of neuroendocrine factors also have the phenomenon of self-discipline slowed with the growth of age. Further experiments suggest that this may be due to the decrease of cAMP content in the sinoatrial node cells and the displacement of the threshold potential of the paced ion current If to the negative direction resulting in a decrease in the rate of automatic depolarization in the fourth phase of the sinoatrial node cells and finally the change of heart rate SLOW. The above results show that the growth rate of heart rate slowed down, in addition to the impact of neurohumoral factors, the changes in the sinus node cells self-discipline also played a role.