Assessment of the effect of monohydroxy alcohols, unsaturated fatty acids, organophosphate compounds on the enzymatic ATP-hydrolysis in the cell membranes of the smooth muscle of rat colon

Abstract

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.

Keywords

• aliphatic monohydroxy alcohols
• ATP-hydrolases
• colonic smooth muscle
• fenamiphos
• Na(+)-K(+)-AТРase
• organophosphate compounds