Hak J B, van Beek J H, Westerhof N
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
Pflugers Arch. 1993 May;423(3-4):324-9. doi: 10.1007/BF00374412.
The purpose of this study was to investigate the effect of acidosis on the mean response time of mitochondrial oxygen consumption to steps in heart rate and in left ventricular balloon volume. The mean response time may be viewed as the average delay between a change in adenosine triphosphate (ATP) hydrolysis and oxygen consumption. The mean response time is calculated by subtracting the transport time, required for diffusion of oxygen and for convective transport through the coronary vessels, from the response time measured in the coronary venous effluent. Eight isolated rabbit hearts were perfused according to Langendorff using Tyrode solution at 28 degrees C. Arterial perfusate pH was lowered from 7.30 +/- 0.03 (mean +/- SD) to 6.59 +/- 0.02 by increasing the CO2 tension. At pH 7.3 the mean response time was 12.6 +/- 1.6 s, independent of the time after isolation of the heart. During acidosis, applied 40-75 min after isolation of the heart, the mean response time was 21.4 +/- 0.7 s and increased to 32.6 +/- 4.3 s during acidosis, 85-120 min after isolation. Thus the retardation of the metabolic response by acidosis might depend on the condition of the heart. A decrease of mitochondrial ATP synthetic capacity during acidosis may contribute to the retardation of the metabolic response. Since determination of the mean response time at 37 degrees C is not yet feasible, the experiments were done at 28 degrees C. Extrapolation of our findings to 37 degrees C appears premature.
本研究的目的是调查酸中毒对线粒体氧消耗对心率和左心室球囊容积变化的平均反应时间的影响。平均反应时间可被视为三磷酸腺苷（ATP）水解变化与氧消耗之间的平均延迟。平均反应时间是通过从冠状静脉流出物中测量的反应时间中减去氧扩散和通过冠状血管的对流运输所需的运输时间来计算的。八只离体兔心在28℃下按照Langendorff法用台氏液灌注。通过增加二氧化碳张力，将动脉灌注液的pH从7.30±0.03（平均值±标准差）降至6.59±0.02。在pH 7.3时，平均反应时间为12.6±1.6秒，与心脏离体后的时间无关。在心脏离体后40 - 75分钟施加酸中毒时，平均反应时间为21.4±0.7秒，在心脏离体后85 - 120分钟的酸中毒期间增加到32.6±4.3秒。因此，酸中毒对代谢反应的延迟可能取决于心脏的状况。酸中毒期间线粒体ATP合成能力的下降可能导致代谢反应的延迟。由于在37℃下测定平均反应时间尚不可行，实验在28℃下进行。将我们的研究结果外推到37℃似乎为时过早。
