Release of compartment-specific enzymes from neonatal rat heart cell cultures during anoxia and reoxygenation

The effects of anoxia and substrate deprivation on the extent of the release of several intracellular marker enzymes and DNA were studied using monolayer cultures of neonatal rat heart cells. After varying periods of anoxia, in a number of experiments followed by 1 h of reoxygenation and substrate repletion, the cells were analysed for cytoplasmic, lysosomal, and mitochondrial enzymes, and for nuclear DNA. Cellular enzyme activity and DNA content at any time during incubation were compared with the remaining activity of alpha-hydroxybutyrate dehydrogenase (HBDH), a cytoplasmic enzyme. The study demonstrates that the ultimate extent of enzyme depletion induced by anoxia with or without reoxygenation, is high (greater than 80%) for cytoplasmic enzymes, is intermediate for sarcolemmal and lysosomal enzymes, and enzyme associated with the mitochondrial outer membrane (about 50%) and small (less than 10%) for enzymes associated with the mitochondrial inner membrane, and for nuclear DNA.