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

已有研究表明肌浆网(SR)参与了 心肌对灌流液[Ca~(2+)]、[H~+]和[H~+]变化的反应 刺激率。进行了两个系列的实验来研究 这些建议。首先，细胞内[Ca~(2+)](CaI)和 测定6月龄和24月龄大鼠乳头肌的张力 心脏，在灌流期间[Ca~(2+)]和刺激率的变化。心 来自古老动物的肌肉，其中SR功能被认为是 抑郁，对刺激率变化的反应不同 灌流液[Ca~(2+)]较高。这种与年龄相关的差异与 在该模型中，张力的形成依赖于SR对钙的循环。在……里面 第二系列实验测量了cai和显张力。 乳头肌在暴露于不同类型的酸中毒期间。 SR的抑制剂被用来检测SR在 肌肉对酸中毒的反应。这项研究表明，有一种 酸中毒期间早期、短暂的紧张恢复，这是由于 增加肌浆网钙离子释放。蔡氏的振荡是 由SR产生，这可能在某些 各种类型的心律失常，也可由酸中毒引起。初步 对6月龄和24月龄大鼠的数据分析表明，这一早期 在酸中毒期间观察到的张力恢复可能不到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.