Resumo

CERVINO, V  e  BENAIM, G. Efecto del Etanol y del Fosfatidiletanol sobre la Ca²⁺-ATPasa de la Membrana Plasmática (in situ). AVFT [online]. 2002, vol.21, n.1, pp.83-90. ISSN 0798-0264.

Ethanol and calmodulin additively stimulate the plasma membrane calcium pump from human erythrocytes. Thus, this enzyme have been the subject of studies oriented to establish the mechanism of action of this alcohol. However, most of the efforts has been directed to the purified dissolved form of the calcium pump. It is relevant to be able to extrapolate the evidences obtained on this form, which is devoid of natural lipids, to the form on the intact membrane, in order to be able to establish the possible pharmacological relevance of this effect. In this work we show that the effect of ethanol and other short chain aliphatic alcohols as methanol, n-propanol and n-butanol, on the Ca²⁺-ATPase present in plasma membrane fragments (ghosts) from human erythrocytes is essentially identical to that observed on the purified calcium pump. We also show in the same system that the stimulation obtained by ethanol is reversible, as it occurs «in vivo». On the other hand, similar to the purified enzyme, in this work we show that phosphatidylethanol, an acidic phospholipid which is accumulated in the plasma membrane after alcohol ingestion, is able to stimulates the Ca²⁺-ATPase present in membrane fragments, increasing the affinity for Ca²⁺ to levels beyond those obtained in the presence of calmodulin and ethanol. It was also observed an additive effect on the enzyme affinity for Ca²⁺ and on the Vmax, when both etanol and phosphatidylethanol are simultaneously present, which allows us to postulate that this effect could occur on the intact cell.

Palavras-chave : Ca²⁺-ATPasa; Ethanol; Alcohol; Membrane; Phosphatidylethanol.