Phospholipid alterations and membrane injury during myocardial ischemia.

Several independent studies have demonstrated that there is a degradation of membrane phospholipids during myocardial ischemia. At present, most of the data support the initial activation of a phospholipase A pathway of phospholipid degradation. The extent of total phospholipid degradation is in the nanomole per gram wet weight quantity, as opposed to ischemic liver, in which the extent of phospholipid depletion approaches the micromole per gram wet weight level. However, in vitro studies suggest that calcium permeability properties and other myocardial cell membrane functions are sensitive to nanomole levels of phospholipid degradation. Clearly, further work is necessary in intact cell and heart preparations to correlate the degradation of phospholipid with the development of irreversible membrane injury during ATP depletion and hypoxia.