Lipid interactions with the cardiac NaS+-HS+ exchanger

Abstract

Cardiac sarcolemmal Na+-H+ exchange is critical for the regulation of intracellular pH and its activity contributes to ischemia/reperfusion injury. It also plays an important role during ischemia/reperfusion injury in diabetics. The Na+-H + exchanger is altered during insulin-dependent diabetes mellitus, however, the mechanism for this inhibition has yet to be determined. Coincidentally, the cardiac sarcolemmal membrane phospholipids are also altered during insulin-dependent diabetes mellitus. It has been suggested that the membrane phospholipid environment does not modulate Na+-H+ exchange. The present study was carried out to determine the effects on Na+-H + exchange of modifying the endogenous membrane phospholipids through the addition of exogenous phospholipase AZ, phospholipase C, phospholipasase D, specific phospholipids and saturated and unsaturated fatty acids. The effects on Na+-H+ exchange of a direct addition of specific lipids to the sarcolemmal membrane was investigated. 22Na was utilized asa tracer to determine the amount of H +-dependent Na+ uptake. This study demonstrates that specific alterations in the cardiac sarcolemmal membrane phospholipids influence the activity of the Na+-H+ exchanger. (Abstract shortened by UMI.)