Institute of Immunology and Physiology of Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., 620049 Yekaterinburg, Russia.
Int J Mol Sci. 2022 Apr 10;23(8):4186. doi: 10.3390/ijms23084186.
There is a lack of data about the contractile behavior of the right atrial myocardium in chronic pulmonary heart disease. We thoroughly characterized the contractility and Ca transient of isolated right atrial strips of healthy rats (CONT) and rats with the experimental model of monocrotaline-induced pulmonary hypertension (MCT) in steady state at different preloads (isometric force-length), during slow force response to stretch (SFR), and during post-rest potentiation after a period of absence of electrical stimulation (PRP). The preload-dependent changes in the isometric twitch and Ca transient did not differ between CONT and MCT rats while the kinetics of the twitch and Ca transient were noticeably slowed down in the MCT rats. The magnitude of SFR was significantly elevated in the MCT right atrial strips and this was accompanied by the significantly higher elevation of the Ca transient relative amplitude at the end of SFR. The slow changes in the contractility and Ca transient in the PRP protocol did not differ between CONT and MCT. In conclusion, the alterations in the contractility and Ca transient of the right atrial myocardium of monocrotaline-treated rats with pulmonary hypertension mostly concern the elevation in SFR. We hypothesize that this positive inotropic effect in the atrial myocardium may (partly) compensate the systolic deficiency of the right ventricular failing myocardium.
关于慢性肺心病右心房心肌的收缩行为，目前数据匮乏。我们彻底描述了健康大鼠（CONT）和慢性野百合碱诱导肺动脉高压（MCT）实验模型的右心房条带在不同前负荷（等长力-长度）下的收缩性和钙瞬变，在拉伸时的缓慢力反应（SFR）期间，以及在一段时间没有电刺激后的后休息增强（PRP）期间。CONT 和 MCT 大鼠的等长抽搐和钙瞬变的前负荷依赖性变化没有差异，而抽搐和钙瞬变的动力学在 MCT 大鼠中明显减慢。MCT 右心房条带的 SFR 幅度显著升高，这伴随着 SFR 结束时钙瞬变相对幅度的显著升高。PRP 方案中收缩性和钙瞬变的缓慢变化在 CONT 和 MCT 之间没有差异。总之，肺动脉高压野百合碱处理大鼠右心房心肌收缩性和钙瞬变的改变主要涉及 SFR 的升高。我们假设心房心肌的这种正性肌力作用可能（部分）补偿右心室衰竭心肌的收缩不足。
