Hak J B, Van Beek J H, Eijgelshoven M H, Westerhof N
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
Am J Physiol. 1993 Feb;264(2 Pt 2):H448-53. doi: 10.1152/ajpheart.1993.264.2.H448.
The effect of regulation of mitochondrial dehydrogenase activities on the mean response time of mitochondrial oxygen consumption, which characterizes the delay between changes in ATP hydrolysis and changes in oxygen consumption, was investigated in isolated rabbit hearts and perfused with Tyrode solution at 28 degrees C. Perfusion with ruthenium red (RR) blocks mitochondrial calcium uptake and thus decreases mitochondrial dehydrogenase activities. Perfusion with pyruvate increases pyruvate dehydrogenase activity. The mean response time was 11.8 +/- 0.7 s (means +/- SE) during control, 12.2 +/- 1.2 s during perfusion with 0.9 microgram/ml RR, and 20.7 +/- 3.4 s during perfusion with 2.1 micrograms/ml RR. Blockade with 0.9 microgram/ml RR, which is presumably partial, did not slow the response, suggesting that mitochondrial calcium uptake may not be rate limiting. Strong blockade of mitochondrial calcium uptake increases the mean response time, presumably due to decreased calcium activation of the mitochondrial dehydrogenases. Perfusion with pyruvate significantly decreased the mean response time to 10.0 +/- 1.4 s compared with 11.9 +/- 0.7 s during perfusion with glucose. This decrease with pyruvate is not compatible with a shift to regulation by high-energy phosphates but may reflect increased mitochondrial oxidative capacity caused by increased NADH levels.
在28℃下用台氏液灌注的离体兔心脏中，研究了线粒体脱氢酶活性调节对线粒体氧消耗平均反应时间的影响，该反应时间表征了ATP水解变化与氧消耗变化之间的延迟。用钌红（RR）灌注可阻断线粒体钙摄取，从而降低线粒体脱氢酶活性。用丙酮酸灌注可增加丙酮酸脱氢酶活性。对照期间平均反应时间为11.8±0.7秒（平均值±标准误），用0.9微克/毫升RR灌注时为12.2±1.2秒，用2.1微克/毫升RR灌注时为20.7±3.4秒。用0.9微克/毫升RR阻断（可能是部分阻断）并未减慢反应，这表明线粒体钙摄取可能不是限速步骤。线粒体钙摄取的强烈阻断会增加平均反应时间，推测是由于线粒体脱氢酶的钙激活降低。与用葡萄糖灌注时的11.9±0.7秒相比，用丙酮酸灌注显著降低平均反应时间至10.0±1.4秒。丙酮酸导致的这种降低与向高能磷酸盐调节的转变不相符，但可能反映了由NADH水平升高引起的线粒体氧化能力增加。
