SHORT CHAIN FATTY ACID INHIBITION OF RAT BRAIN Na‐K ADENOSINE TRIPHOSPHATASEI

Abstract

— The possibility was considered that the sleep-like state seen after injection of short chain fatty acids salts into animals is a result of inhibition of the sodium-potassium activated ATPase. Tris salts of short chain fatty acids inhibited brain Na-K ATPase activity in vitro at concentrations similar to intravenous levels causing narcosis in vivo. The inhibition depended on the logarithm of the concentration of a given acid. The concentration of acid anion which caused 50 per cent inhibition of the enzyme system (I₅₀) was determined for straight and branched chain acids with 4–12 carbon atoms per molecule. The log of I₅₀ concentrations plotted against the number of carbon atoms in the molecule gave a straight line; the inhibitory capacity of an acid increased by a factor of 2·3 for each -CH₂- added to the carbon chain.