Krukenkamp I B, Silverman N A, Levitsky S
Department of Surgery, University of Illinois College of Medicine, Chicago.
Surgery. 1989 Aug;106(2):239-46; discussion 246-7.
The efficiency of transferring the total energy generated by ventricular contraction (pressure-volume area, PVA) to external work (EW) and internal work (IW) and the myocardial oxygen consumption (MVO2) at zero PVA were determined during volume loading on right heart bypass before and after a 50% augmentation (CaCl2, 0.03 mEq/kg/min, n = 7) or depression (20 minutes of 37 degrees C ischemia with 30 minutes of reperfusion, n = 7) of the contractile state. An increased EW efficiency (64% +/- 7% vs. 81% +/- 6%, p less than 0.01) with reciprocally decreased IW efficiency (36% +/- 7% vs. 19% +/- 6%, p less than 0.01) occurs with calcium chloride-augmented contractility. A reversible ischemia and reperfusion insult has the converse effect on these relative efficiencies (EW, 73% +/- 4% vs. 49% +/- 4%; IW, 27% +/- 4% vs. 51% +/- 4%; each p less than 0.01). Calcium chloride increases the oxygen requirements of both basal metabolism (28 +/- 2 vs. 67 +/- 9 ml O2/beat/100 gm LV, p less than 0.01) and fiber shortening (11 +/- 5 vs. 62 +/- 11 ml O2/beat/100 gm LV, p less than 0.01). The postischemic heart has a decreased oxygen need for shortening (20 +/- 2 vs. 3 +/- 4 ml O2/beat/100 gm LV, p less than 0.01), paralleling the depressed inotropic state. This new model of compartmentalized chemomechanical transduction may allow specific modulation of the energetic derangements attendant to the surgically treated heart.
在右心旁路循环进行容量负荷期间，分别在心肌收缩状态增强50%（氯化钙，0.03 mEq/kg/min，n = 7）或减弱（37℃缺血20分钟后再灌注30分钟，n = 7）之前和之后，测定心室收缩产生的总能量（压力-容积面积，PVA）转化为外部功（EW）和内部功（IW）的效率以及零PVA时的心肌耗氧量（MVO2）。氯化钙增强心肌收缩力时，EW效率增加（64%±7%对81%±6%，p<0.01），而IW效率相应降低（36%±7%对19%±6%，p<0.01）。可逆性缺血再灌注损伤对这些相对效率有相反的影响（EW，73%±4%对49%±4%；IW，27%±4%对51%±4%；各p<0.01）。氯化钙增加基础代谢（28±2对67±9 ml O2/次搏动/100 g左心室，p<0.01）和纤维缩短（11±5对62±11 ml O2/次搏动/100 g左心室，p<0.01）的氧需求。缺血后心脏缩短所需的氧需求降低（20±2对3±4 ml O2/次搏动/100 g左心室，p<0.01），与心肌收缩力降低状态平行。这种新的化学机械转导分区模型可能允许对手术治疗心脏伴随的能量紊乱进行特异性调节。
