Effects of Semistarvation on the Absorption of D- and L-Amino Acids and on the Electrical Potential across Rat Small Intestine In Vitro

Abstract

Studies have been undertaken on the influence of semistarvation on the in vitro absorption of amino acids in the rat intestine. Transmural transport of D- and L-isomers of various neutral and basic amino acids, as measured by the everted sac method and expressed either per gut weight or per 100g body weight, impartially increased after semistarvation. Metabolism of acidic amino acids as represented by the amount of alanine formed was elevated in semistarved intestine, while their uphill transport was yet undemonstrable. Also increased in general after semistarvation was the electrical potential difference across the gut wall, which was evoked during absorption of actively transportable amino acids and certain acidic amino acids. Epithelial cells isolated from semistarved intestine took up more amino acids and showed higher activity of certain marker enzymes than did their control counterparts. The data have been discussed in relation to effects of semistarvation on the activity of sodium pump linked to the transport mechanisms in the epithelial cells and their functional priority over other tissues in adapting to deficient nutritional conditions.