Cardiac ATP breakdown and mechanical function during recurrent periods of anoxia.

The effect of repeated short anoxic or ischemic periods on ATP breakdown and cardiac function remains controversial. To analyze this issue further and to study the regulation of adenine nucleotide breakdown during recurrent cardiac anoxia, we compared two different protocols of intermittent anoxia. Four rat hearts, perfused according to Langendorff, were exposed to 12 periods of anoxia, each lasting 1 minute, with reoxygenation periods of 3 minutes (protocol A).

Xanthine oxidoreductase activity in perfused hearts of various species, including humans.

Oxygen free radicals generated by xanthine oxidase have been implicated in cardiac damage. The activity of xanthine oxidase/reductase in adult rat heart is considerable. Its assay gives controversial results for other species, for example, rabbits and humans.

Different ATP-catabolism in reperfused adult and newborn rat hearts.

Age-dependent differences in the effects of ischemia and reperfusion on ATP breakdown were studied in perfused adult and newborn (10 days old) rat hearts. No-flow ischemia (15 min at 37, 30, or 23 degrees C) was applied and reperfusion (20 min at 37 degrees C) was studied after ischemia at 23 or 37 degrees C. Hypothermia during ischemia protected both age groups to a similar degree against ATP decline, which was linear with temperature.