Studies on oxygen and volume restriction in cultured cardiac cell: possible rearrangement of sarcolemmal lipid moieties during anoxia and ischemia-like states.

Cultured heart cells have been shown useful for investigating states of oxygen and volume restrictions, simulating anoxia and ischemia-like states at cellular levels. The sarcolemma has been implicated as one of the early sites of ischemic damage; therefore, lactoperoxidase catalyzed radioiodination was used to study accessibility of the sarcolemmal lipid moieties to this enzymatic probe, reflecting their exposure to the extracellular environment, hence the biophysical state of the sarcolemma. These studies have shown that within one hour of 'ischemic' injuries: (1) The degree of labelling in the total phospholipid fraction is considerably increased; and (2) Profound changes in the relative extent of labelling of different phospholipid classes were observed. The PE/PC labelling ratio increases dramatically with the progress of ischemia-like state. We suggest that early during ischemic injury, reorganization of the cell surface phospholipids occurs and discuss possible relations to the energy charge of the cell.