Reperfusion injury induced by augumented oxygen uptake in the initial reperfusion period. Possible efficacy of extreme hemodilution

This study was designed to investigate the relationship between myocardial oxygen consumption and oxygen-induced myocardial injury. Dog hearts were exposed to 40 min normothermic ischemia and then reperfused for 10 min with three oxygenated perfusates containing different hemoglobin concentrations and with moderate hemodilution. The experimental groups consist of a moderate hemodilution group (Group M) receiving 8 g/dl of hemoglobin, an extreme hemodilution group (Group E) given 4 g/dl of hemoglobin, and a hemoglobin-free autologous plasma group (Group F). Hearts in the non-ischemic control group (Group C) were also perfused with moderate hemodilution throughout. In Group C, Group M and Group E, the O2 tension of perfusates was maintained at about 100 mmHg and in Group F, at over 300 mmHg. Oxygen extraction at 5 min after reperfusion in Group C was 14%, in Group M and Group E less than 10%, but in Group F 70%. Oxygen consumption in Group F was more than twice that in Group E and surpassed that in Group C. Group M also showed a significant increase in oxygen consumption compared with Group E at 5 min after reperfusion. Among the ischemic groups, Group E showed improvement of left ventricular function almost comparable to Group C accompanied by a rapid decrease in myocardial lactate, improved preservation of myocardial adenine nucleotides and prevention of myocardial lipid peroxidation. In contrast, Group F showed persistently higher values of lipid peroxides and lactate, the poorest recovery of adenine nucleotides, and impairment of left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)