Effects of hydrogen peroxide on cardiac function and post-ischaemic functional recovery in the isolated 'working' rat heart.

The effects of hydrogen peroxide on the normal and ischaemic myocardium were investigated using the isolated 'working' rat heart preparation. In the range 0-3 microM no changes in heart rate, aortic flow, coronary flow, or aortic pressure were observed. Between 3 and 30 microM, however, there was a dose-dependent fall in aortic flow and an accompanying increase in coronary flow, the total cardiac output remaining unchanged. At concentrations about 30 microM functional failure occurred. Following a 24-min ischaemic period during which time 6 microM hydrogen peroxide was infused via the aorta at a constant rate to remove any vasodilatory effect, all hearts failed to recover. In contrast, 50% of control hearts recovered pump function. In conclusion, therefore, hydrogen peroxide can reduce function in the aerobic working rat heart and may exert a vasodilatory effect. When this effect is eliminated hydrogen peroxide affords no protection during ischaemia and appears to exacerbate tissue injury.