EXCITATION-CONTRACTION IN RAT MYOCARDIUM--ALTERATIONS WITH ADULT AGING

肌浆网（SR）参与了 心肌对灌流液[Ca ~（2+）]、[H ~（2+）]和 刺激率 进行了两个系列的实验来研究 这些建议。 在第一，细胞内[Ca 2 +]（Cai）和发展 测量6和24月龄大鼠乳头肌张力 心脏，在灌流液[Ca 2 +]和刺激率的变化。 心脏 肌肉从老年动物，其中SR功能被认为是 抑郁，对刺激率的变化有不同的反应， 灌流液[Ca ~（2+）]升高。 这种年龄相关的差异与 一个模型，其中开发的张力依赖于钙循环的SR。 测量第二系列实验、Cai和展开张力 在乳头肌暴露于不同类型的酸中毒。 使用SR的抑制剂来检查SR在细胞凋亡中的作用。 肌肉对酸中毒的反应。 这项研究表明， 酸中毒期间张力的早期短暂恢复，这是由于 增加Ca 2+从SR释放。 由SR产生，这可能是重要的起源， 各种类型的心律失常，也可以由酸中毒引起。 初步 对6个月和24个月大的大鼠的数据分析表明， 酸中毒期间观察到的张力恢复可能少于24个月 老老鼠

It has been suggested that the sarcoplasmic reticulum (SR) is involved in the response of heart muscle to changes of perfusate [Ca2+], [H+] and stimulation rate. Two series of experiments were undertaken to investigate these suggestions. In the first, intracellular [Ca2+] (Cai) and developed tension were measured in papillary muscles from 6 and 24 month old rat hearts, during changes of perfusate [Ca2+] and stimulation rate. Heart muscle from the old animals, in which SR function is thought to be depressed, responded differently to changes of stimulation rate when perfusate [Ca2+] was high. This age-related difference was compatible with a model in which developed tension depended on Ca2+ cycling by the SR. In the second series of experiments, Cai and developed tension were measured in papillary muscles during exposure to different types of acidosis. Inhibitors of the SR were used to examine the role of the SR in the response of the muscle to acidosis. This study showed that there is an early transient recovery of tension during acidosis which is due to increased Ca2+ release from the SR. Oscillations of Cai which are generated by the SR, and which may be important in the genesis of some types of arrhythmias, could also be produced by acidosis. Preliminary analysis of data from 6 and 24 month old rats suggests that this early recovery of tension observed during acidosis may be less than in 24 month old rats.