Myocardial high energy metabolism in hemorrhagic shock

In each pair of 19 pairs of dogs, one dog was subjected to a modified Wigger's shock preparation, and the other underwent duplicate interventions but was not placed in shock. For the dogs placed in shock, after slow bleeding to 35 mm Hg mean aortic pressure, pressure was maintained at this level and when one third of the shed blood volume had been reinfused, myocardial biopsy specimens were taken by means of an especially designed suction apparatus that propelled the specimen into liquid nitrogen. Assays were made for ATP, ATPase, inorganic phosphate (Pi), and creatine phosphate (CP). A Polytron disruptor was used to obtain isolated mitochondrial preparations for oxidative phosphorylation indices, and P/O ratios, respiratory control rates, and qO₂ values were calculated. Myocardial contractility was assessed from an SF 1 catheter introduced into the left ventricle. The first derivative of left ventricular pressure at a developed pressure of 20 mm Hg was used as an index of intrinsic myocardial contractility. The results showed normal mitochondrial respiration with adequate generation of high energy phosphate compounds in profound hemorrhagic shock. The presence of increased creatine phosphate stores in the presence of demonstrated normal lytic systems suggests an adequacy of myocardial oxygen delivery relative to cellular demand in hemorrhagic shock, despite significantly reduced coronary perfusion.