Lysophospholipids do not directly modulate Na(+)-H+ exchange.
Lysophosphatidylcholine (LPC) has been reported to stimulate Na(+)-H+ exchange in rat cardiomyocytes. This action may be important in pathological conditions like ischemic injury where LPC is generated and Na(+)-H+ exchange activation is an important determinant of cardiac damage and dysfunction. It is unclear, however, if this stimulation of Na(+)-H+ exchange by LPC occurs through a direct action on the exchanger or through stimulation of a second messenger pathway. The purpose of the present investigation was to determine if lysolipids could directly affect Na(+)-H+ exchange. Purified cardiac sarcolemmal membranes were isolated and Na(+)-H+ exchange was measured by radioisotopic methods following addition of LPC. There were no effects of LPC on Na(+)-H+ exchange at LPC concentrations of < or = 100 microM at all reaction times examined. Lysophosphatidylethanolamine (LPE), lysophosphatidylserine (LPS), lysophosphatidylinositol (LPI) and lysoplasmenylcholine (LP(E)C) also did not alter Na(+)-H- exchange at all concentrations and reaction times examined. We conclude that any stimulatory effects of lysolipids on Na(+)-H+ exchange do not occur through a direct action on the exchanger or its membrane lipid environment and must occur through a second messenger pathway.
Cell Biology Laboratory, Division of Stroke and Vascular Disease, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada.
Danny P
DP
Goel
L David A
LD
Ford
Grant N
GN
Pierce
D000818:Animals; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D008246:Lysophospholipids / Q000145:classification* / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism; D012508:Sarcolemma / Q000378:metabolism; D015290:Second Messenger Systems; D012964:Sodium / Q000378:metabolism / Q000493:pharmacokinetics; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology*; D013552:Swine; D013997:Time Factors
D008246:Lysophospholipids; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium