Effects of Catalase on Volume-Overload Heart Failure

Summary

Exogenous oxygen free radicals (OFRs) have been reported to depress cardiac function and contractility. The decrease in cardiac function and contractility in chronic volume overload could be due to increased levels of OFRs. We therefore investigated the effects of volume overload of 9 months duration in the absence and presence of catalase treatment on cardiac function and contractility; left ventricular malondialdehyde (MDA), a lipid peroxidation product; and left ventricular antioxidant reserve, measured as left ventricular chemiluminescence (LV-CL) in dogs. Dogs were divided into three groups: group I, control; group II, mitral regurgitation (MR) of 9 months duration; and group III, same as group II but supplemented with polyethylene glycol (PEG)-catalase (5000IU/kg/week, intravenously).

Mitral regurgitation was produced by detaching two or more chordae tendinae of the mitral valve to raise the left atrial pressure to 2.5 or 3 times normal. Volume overload produced a decrease in myocardial contractility [(+)dp/dt, (+)(dp/dt)/PAW, V_max] and function [CI and LVEDP], which was associated with an increase in cardiac MDA and LV-CL. An increase in LV-CL indicates a decrease in the antioxidant reserve and vice-versa. There was an increase in systemic vascular resistance (TSVR). Prevention of a volume overload-induced decrease in cardiac function and contractility, and an increase in TSVR by PEG-catalase was associated with a decrease in cardiac MDA and an increase in antioxidant reserve. These results suggest that OFRs are involved in chronic volume overload—induced decrease in cardiac function and contractility.