ETHANOL PROTECTS THE HEART AGAINST THE CALCIUM PARADOX INJURY

Rat hearts were depleted of Ca2+ (<10-9M) for 10 min, followed by 15 min of Ca2+-repletion. The calcium paradox injury occurs during Ca2+-repletion, after a period of calcium depletion. The calcium paradox injury was assessed by percent recovery (hemodynamics, [Ca2+]i, and energy levels) during Ca2+-repletion. A decrease in Na+ concentration during Ca2+-depletion did not allow for recovery during Ca2+-repletion, however 2.5% and 5% ethanol during Ca2+-depletion allowed for an approximate 50% recovery during Ca2+-repletion. A combination of ethanol (2.5% or 5%) with a low extracellular Na+ concentration (88 mM) allowed for complete recovery. Ethanol prevented a depletion of diastolic [Ca2+]i during Ca2+-depletion, and allowed for a return of normal diastolic [Ca2+]i during Ca2+-repletion. Ethanol modulates the activity of the Na+ Ca2+ exchanger and protects against the Ca2+-paradox injury. © 1990.