Effect of ethanol on regulation of (Na + K)-adenosine triphosphatase by aldosterone and dexamethasone in cultured renal papillary collecting duct cells

Abstract

Chronic ethanol exposure causes alterations in biologic membranes of different cell types. (Na + K)–adenosine triphosphatase (ATPase), a membrane-bound enzyme inhibited by the acute presence of ethanol, increases its activity in rat kidney after chronic ethanol consumption. The aim of this investigation was to evaluate the effect of ethanol on the modulation of (Na + K)-ATPase by glucocorticoids and mineralocorticoids in renal papillary collecting duct cells. Cultured renal papillary collecting duct cells were exposed to a medium containing 150 mM ethanol plus either 100 nM aldosterone or 10 nM dexamethasone. Control groups were cultured in the absence of ethanol and/or the hormones. Mg2+-ATPase was used as control enzyme. The activity of ATPases was measured by ATP hydrolysis. Ethanol increased the activities of (Na + K)-ATPase and Mg2+- ATPase in 29 and 33% of controls, respectively; only (Na + K)-ATPase activity was elevated in the presence of aldosterone or dexamethasone, whereas Mg2+-ATPase was unaltered by these hormones. The effects of aldosterone and dexamethasone on (Na + K)-ATPase activity were augmented by ethanol in 50 and 19% of controls, respectively. These results suggest that ethanol treatment enhances the upregulation of (Na + K)-ATPase activity by both aldosterone and dexamethasone, in cultured renal papillary collecting duct cells.