VOLATILE ANESTHETICS & RAT HEART CELL CONTRACTILITY

本提案的目标是确定 广泛使用的挥发性药物的心肌保护作用 麻醉剂氟烷、恩氟烷和异氟烷。 孤立的，完整的 大鼠心脏细胞，无论是单独的还是悬浮的，将用于 实验 连续测量单个 细胞将揭示自发收缩波的特性 刺激抽搐和它们的相互作用。 麻醉剂- 这些变量的诱导变化将提供以下信息： 肌浆网钙代谢的变化 在完整的细胞中。 细胞内游离钙的测定 荧光染料quin 2的浓度将显示 麻醉剂改变了这种浓度， 咖啡因，将揭示在多大程度上代理改变量 的钙存储在SR。膜片钳电极将被应用于 单细胞，正常的动作电位和缓慢的向内 将测量电流。 与此同时 电生理测定，收缩活动将是 监测。 因此，麻醉变化之间的相关性 将产生电变量和收缩性。 逆转 增加麻醉剂诱导的心肌抑制 通过加入β激动剂异丙肾上腺素， 通过分析自发波和抽搐进行评估 性能和电生理测量。 除了 揭示了抑郁症逆转的完全性， 如果逆转不完全，可能的机制是 麻醉剂/β受体激动剂引起心律失常 可以解释相互作用。 总之，这些实验 建议将定义麻醉作用的缓慢内向电流 和/或SR钙代谢，并将这些发现与实际 收缩力的变化。

The goal of this proposal is to determine the mechanism of the myocardial depressant effects of the widely used volatile anesthetics halothane, enflurane and isofluane. Isolated, intact rat heart cells, either singly or in suspension, will be utilized for the experiments. Continuous measurement of the length of single cells will reveal the properties of spontaneous contractile waves and stimulated twitches and their interaction. Anesthetic- induced alterations in these variables will provide information on changes in the Ca metabolism of the sarcoplasmic reticulum (SR) in intact cells. Determination of the free intracellular Ca concentration with the fluorescent dye quin2 will show whether anesthetics alter this concentraton and, through the use of caffeine, will reveal to what extent the agents change the amount of Ca stored in the SR. Patch clamp electrodes will be applied to single cells, and normal action potentials and the slow inward current will be measured. Simultaneous with these electrophysiologic determinations, contractile activity will be monitored. Thus, correlation between anesthetic changes in electrical variables and contractility will be made. Reversal of the anesthetic-induced myocardial depression by increasing extracellular Ca and by adding the beta agonist isoproterenol will be evaluated by analysis of spontaneous waves and twitch properties and by electrophysiologic measurements. In addition to revealing the completeness of reversal of the depression and the reason if reversal is not complete, a possible mechanism for the production of arrhythmias by the anesthetic/beta agonists interaction may be elucitated. Taken together, the experiments proposed will define anesthetic action on the slow inward current and or SR Ca metabolism and correlate these findings with actual changes in contractility.