Increased production of oxygen free radicals by polymorphonuclear leukocytes in heart failure due to aortic stenosis.

Oxygen free radicals have been linked to a wide variety of cellular damage in biological systems. Polymorphonuclear (PMN) leukocytes stimulation is one of the known sources for oxygen free radicals. It has been suggested that oxygen free radicals depress the excitation-contraction coupling in cardiac muscle. It is possible that a decrease in the myocardial contractility in heart failure might be due to an increased oxygen-free-radical-producing activity of PMN leukocytes. The authors studied, therefore, the release of oxygen free radicals, as measured by luminol-dependent chemiluminescence activity, from the PMN leukocytes in dogs with heart failure due to aortic stenosis. Hemodynamics and phagocytic activity of PMN leukocytes were studied in 6 control dogs and 6 dogs with aortic stenosis of six to nine months' duration. There was a significant decrease in the index of myocardial contractility and an increase in the left ventricular end-diastolic pressure in dogs with aortic stenosis, suggesting left ventricular failure in these dogs. Although there was a tendency for a decrease in the cardiac index in dogs with aortic stenosis, the decrease was not significant. Phagocytic activity of PMN leukocytes in blood was studied in control dogs and dogs with aortic stenosis. Phagocytosis was initiated by addition of opsonized zymosan and chemiluminescence was monitored by use of a luminometer. The peak chemiluminescence activity of the PMN leukocytes in blood of dogs with heart failure was about threefold greater than that in the blood from control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)