A. A. Kaplia, S. V. Midyk¹, S. V. Khyzhnyak¹

¹National University of Life and Environmental Sciences of Ukraine, Kyiv;
e-mail: kaplyaalex@gmail.com

The differences of the structural-functional stability of ATP-hydrolases to the action of the short-chain aliphatic monohydroxy alcohols and long-chain unsaturated fatty acids (UFAs) with wide range of the membrane-acting effectiveness were evaluated in the colonic smooth muscle (CSM) cellular membranes. It was shown that Mg²⁺,ATP-hydrolase was more resistant to all tested aliphatic compounds than Na⁺,K⁺-ATPase. There was  a clear relationship between  inhibitory efficiency, chain length (number of carbons) increase and relative polarity decrease  in the series of straight-chain alcohols. Secondary alcohol 2-propanol turned out to be the weaker inhibitor than primary alcohol 1-propanol. The I₅₀ value (мМ) for ATРases decreased in the following succession: ethanol > 2-propanol > 1-propanol > 1-butanol. UFAs were the stronger inhibitors (I₅₀ of μM range) than alcohols (mM range). Oleic acid inhibited Na⁺,K⁺-ATPase with lower efficiency than was detected for arachidonic acid according to the differences in double bonds number; I₅₀ for Mg²⁺,ATP-hydrolase activity was the same for studied UFAs. As well, the organophosphate pesticide fenamiphos proved to be a weak ATPase inhibitor. Comparison of the enzymatic pair of the CSM ATP-hydrolases seems applicable for evaluation of the specific membrane-acting effect of bioactive compounds on Na⁺,K⁺-ATРase activity from the standpoint of its role in mediating of electro-mechanical coupling in intestinal smooth muscles.