ЦИСТАМИН И ЦИСТИН ПОДАВЛЯЮТ ТРАНСПОРТ Na+ В ЭПИТЕЛИИ КОЖИ ЛЯГУШКИ

Abstract

Amphibian skin and other isolated epithelial systems are classical model objects for studying the mechanisms of transepithelial ion transport. Na+ transport in osmoregulatory epithelium is a complex, multicomponent system, which involves Na+ transporting proteins and signaling cascades localized in various cell membranes. The protein components of this system may be a target for oxidative stress. At the same time, the effect of oxidizing and reducing agents on Na+ transport in native epithelial systems, such as frog skin epithelium, practically has not been studied. Using voltage-clamp technique the effect of disulfide-containing oxidizing agents cystine and cystamine on Na+ transport in frog skin was investigated. It has been shown for the first time that the treatment of the skin of the Rana temporaria frog with cystamine or cystine at a concentration of 10 μg/ml suppresses the transepithelial Na+ transport. It was also found that the preincubation with dithiothreitol, which reduces disulfide bonds in proteins, prevents the inhibitory effect of cystamine and cystine. The obtained results indicate that Na+ transport in the frog skin is sensitive to oxidative stress and is modulated by disulfide-containing oxidizing agents, such as cystamine or cystine, and also that the effect of cystamine and cystine on Na+ transport in the frog skin epithelium is mediated by their interaction with functionally important cysteine residues of Na+-transporting proteins.