EFFECTS OF AFTERLOAD AND HEART-RATE ON NAD(P)H REDOX STATE IN THE ISOLATED RABBIT HEART
EFFECTS OF AFTERLOAD AND HEART-RATE ON NAD(P)H REDOX STATE IN THE ISOLATED RABBIT HEART
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DOI：
10.1152/ajpheart.1993.264.2.h433
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发表时间：
1993-02-01
影响因子：
--
通讯作者：
BALABAN, RS
中科院分区：
文献类型：
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作者：
HEINEMAN, FW;BALABAN, RS
在有限底物（仅葡萄糖）和丰富底物（葡萄糖+乳酸）条件下，在离体、常温、工作的兔心脏中使用表面荧光监测NAD（P）H氧化还原状态。为了改变工作，后负荷在75和150 cmH 2 O之间变化，或者心率逐步增加，直到心肌耗氧量（MVO 2）不再增加。后负荷的改变不会引起NAD（P）H荧光的显著变化。心率逐渐增加不会改变NAD（P）H的发射，直到MVO 2开始下降（约300次/min），心室功能失代偿，并有缺血的证据，此时NAD（P）H荧光增加。尽管向灌注液中加入3 mM乳酸盐导致NAD（P）H荧光迅速增加，但NAD（P）H荧光仍然不响应改变的工作负荷。结果提示，NAD（P）H氧化还原状态不是心动过速或后负荷引起心肌呼吸增加的主要刺激因素。然而，尽管心脏工作速率增加，但NAD（P）H保持在相对稳定的水平，这表明减少电子传递链的当量供应与MVO 2增加平行增加。
NAD(P)H redox state was monitored using surface fluorescence in isolated, normothermic, working rabbit hearts under conditions of limited substrate (glucose alone) and abundant substrate (glucose + lactate). To alter work, afterload was varied between 75 and 150 cmH2O or heart rate was increased in steps until no further increase in myocardial oxygen consumption (MVO2) occurred. Alterations in afterload did not cause a significant change in NAD(P)H fluorescence. Progressive increases in heart rate did not alter NAD(P)H emission until MVO2 began to decline (approximately 300 beats/min), ventricular performance decompensated, and there was evidence of ischemia, at which time NAD(P)H fluorescence increased. Although the addition of 3 mM lactate to the perfusate resulted in a rapid increase in NAD(P)H fluorescence, NAD(P)H fluorescence still did not respond to altered workload. The results suggest that NAD(P)H redox state is not the primary stimulus for increased myocardial respiration secondary to tachycardia or afterload. However, despite increased rates of cardiac work, NAD(P)H was maintained at a relatively stable level, suggesting that reducing equivalent supply to the electron transport chain increases in parallel with increased MVO2.