The effect of alkanols on Ca2+ transport in brain mitochondria.
Ethanol stimulates the Na(+)-dependent Ca2+ efflux in brain mitochondria and inhibits the Na(+)-independent Ca(2+)-efflux. Here, we studied the effects of n-alkanols on the various Ca2+ transport processes in brain mitochondria. Only short-chain alcohols (i.e. methanol, ethanol and propanol) stimulated Na+/Ca2+ exchange. The inhibition of H+/Ca2+ exchange was significant only with ethanol. Short-chain alcohols inhibit while long-chain alcohols activate the cyclosporin-sensitive Ca(2+)-efflux. These data suggest that the mechanism of the alkanols' effects on Na+/Ca2+ exchange, H+/Ca2+ exchange and the cyclosporin sensitive pore are entirely different. Alkanols have no effect on the electrogenic Ca2+ uniporter. Ethanol did not affect the apparent K0.5 for Na+ (7.5 mM) of the Na+/Ca2+ exchange. Similarly, the magnitude of the effect of ethanol did not depend on matrix Ca2+ concentration, suggesting that short-chain alkanols do not stimulate the rate of Na+/Ca2+ exchange by increasing the affinity of the carrier to Ca2+in or Na+out. High concentrations of K+, Mg2+ and Ca2+ enhanced the ethanol effect. It is possible that high surface potential attenuates the effect of ethanol. It is suggested that ethanol stimulation of Na+/Ca2+ exchange depends on the modulation of the surface dielectric constant.
Rottenberg
H
H
Pathology Department, Hahnemann University, Philadelphia.
Marbach
M
M
D000433:1-Propanol / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D016572:Cyclosporine; D000431:Ethanol / Q000494:pharmacology*; D000432:Methanol / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism
D000431:Ethanol; D016572:Cyclosporine; D000433:1-Propanol; D012964:Sodium; D002118:Calcium; D000432:Methanol