Importance of the cellular energy level for enzyme release induced by direct membrane damage

A release of intracellular enzymes may occur as a result of energy depletion of the cells or after direct membrane damage. A direct membrane damage, however, may be counteracted by the cell by energy-consuming reactions, thus more or less being dependent of the cellular energy level. Therefore, the association between enzyme release and the energy level was investigated after addition of various agents impairing the normal membrane function, i.e. lysophosphatidylcholine, phospholipases, the Ca ionophore A23187, ouabain and superoxide/H2O2, and after incubation in a hypotonic medium. It was observed that in some types of membrane damage the cellular energy is minimally involved, in other types the extent of enzyme release depends on the cellular energy level, and in some other types the cellular energy is affected but the connection to the enzyme release is not clear. The results also indicate that the effect of membrane-active agents arising in ATP-depleted states may be more severe in ATP-depleted than in normal cells.