Ethanol delays and reverses lysophosphatidylcholine-induced calcium overload in neonatal rat heart cells

Abstract.

Increased lysophosphatidylcholine (LPC) production by the ischemic heart is associated with tissue damage. In vitro, LPC produces an increase in cytosolic [Ca²⁺], usually followed by cell contracture and lysis. Since ethanol reportedly protect cells during ischemia-reperfusion, we wished to determine whether ethanol could protect heart cells against LPC-induced Ca²⁺ overload. Newborn rat heart cells in culture were loaded with Fura-2 and [Ca²⁺]_i recorded in individual cells. The presence of 22 or 44 mM ethanol increased the time required for 10 µM L-palmitoyl-LPC to produce maximal Ca²⁺ accumulation from 8.4±0.4 min (n=47) to 21.1±2.1 min (n=32; P<0.01) and 23.8±1.8 min (n=10; P<0.01) respectively. The onset of the [Ca²⁺]_i increase could be reversed partially by the addition of ethanol (44 or 88 mM). After the addition of 22 mM ethanol, the cells retained the Fura-2 three times longer than under control conditions. Ethanol (88 mM) decreased the critical micelle concentration of LPC, thus decreasing the LPC monomer concentration in this solution. La³⁺ also protected the cells against LPC but no further protection was afforded by the addition of ethanol. Our results suggest that ethanol concentrations commonly found in the blood of social drinkers protect heart cells against the deleterious effect of LPC.