Momomura S, Iizuka M, Serizawa T, Sugimoto T
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Am J Physiol. 1988 Dec;255(6 Pt 2):H1468-75. doi: 10.1152/ajpheart.1988.255.6.H1468.
To test the hypothesis that the rate of left ventricular relaxation can be dissociated from left ventricular stiffness, indexes of stiffness and relaxation were evaluated during mild hypoxia and hypoxia with isoproterenol or caffeine in isovolumically beating, isolated rat heart preparations. In group 1, the hearts were perfused with mild hypoxic buffer for 30 min. In group 2, 10 min of mild hypoxic perfusion was followed by 20 min of mild hypoxia plus isoproterenol (10(-6) M). In group 3, the hearts were perfused with mild hypoxic buffer for 10 min followed by 20 min of hypoxia plus caffeine (10(-3) M) perfusion. In group 1, left ventricular end-diastolic pressure (LVEDP) was elevated only slightly, and time constant of left ventricular relaxation T was also prolonged slightly. In group 2, LVEDP was higher, but T was much shorter than the corresponding values in group 1 (LVEDP, 18 +/- 4 mmHg; T, 31.4 +/- 3.4 ms). In group 3, T was more markedly prolonged, and LVEDP tended to be higher than in group 1. These results indicate that the determinants of left ventricular relaxation and stiffness are not identical and that in certain conditions relaxation can be separated from left ventricular stiffness.
为验证左心室舒张速率可与左心室僵硬度分离的假说，在等容搏动的离体大鼠心脏标本中，于轻度缺氧以及伴有异丙肾上腺素或咖啡因的缺氧状态下，对僵硬度和舒张指标进行了评估。在第1组中，心脏用轻度缺氧缓冲液灌注30分钟。在第2组中，先进行10分钟的轻度缺氧灌注，随后进行20分钟的轻度缺氧加异丙肾上腺素（10⁻⁶M）灌注。在第3组中，心脏先被用轻度缺氧缓冲液灌注10分钟，接着进行20分钟的缺氧加咖啡因（10⁻³M）灌注。在第1组中，左心室舒张末期压力（LVEDP）仅略有升高，左心室舒张时间常数T也略有延长。在第2组中，LVEDP更高，但T比第1组的相应值短得多（LVEDP，18±4 mmHg；T，31.4±3.4毫秒）。在第3组中，T延长得更为明显，且LVEDP往往高于第1组。这些结果表明，左心室舒张和僵硬度的决定因素并不相同，并且在某些情况下，舒张可与左心室僵硬度分离。
