Effect of pyridoxal on the active transport of amino acids by sacs of everted intestine of the golden hamster (Mesocricetus auratus)

Abstract

During the investigation of the uptake of amino acids by Ehrlich mouse ascites carcinoma cells, Riggs, Coyne & Christensen (1953) found that the degree to which glycine was concentrated could be much increased by the addition of certain quantities of pyridoxal to the suspending medium. This effect was also obtained, but to a lesser degree, when L-a, y-diaminobutyric acid and L-methionine were used, while the uptake of L-tryptophan was only stimulated when the neoplastic cells had been grown in pyridoxine-deficient mice (Christensen, Riggs & Coyne, 1954). At any given concentration of amino acid in the suspending medium for these neoplastic cells it was found that there was an optimal concentration of the pyridoxal, and a concentration above this optimum could result in an inhibition of the active transport of the amino acid concerned. Accompanying this increased uptake of amino acid there was found to be a pronounced loss of intracellular potassium. The results suggested that either pyridoxal or a closely related derivative was involved in the mechanism of active transport of amino acids, and that the transfer processes for amino acids and potassium have certain features in common.As it has been shown that rat small intestine (Wiseman, 1953) and hamster small intestine (Wilson & Wiseman, 1954;Wiseman, 1955Wiseman, , 1956) can transport many L-amino acids against a concentration gradient it was decided to investigate the effect of pyridoxal on this intestinal active transport of some amino acids. The hamster small intestine was used in the studies reported in this paper and the in vitro technique of Wilson & Wiseman (1954) was employed. The results show that pyridoxal has no stimulatory effect on the active transport of glycine, L-proline, L-histidine or L-methionine by the normal hamster small intestine when used at concentrations comparable with those which

The effect of semistarvation on absorption by the rat small intestine in vitro and in vivo

“…The small intestine was then removed and everted, and sacs prepared as described by Wilson & Wiseman (1954). Six sacs (3-4 cm in length) were obtained from each small intestine, and their initial and final volumes were measured as described by Wiseman (1957). Occasionally the serosal volume of a sac decreased: such sacs were discarded.…”

Digestive System

“…Because the pyruvate concentration did not fall, that acid used must have come from cellular metabolism. Pyridoxal may be required in transamination, but added pyridoxal which increases amino acid accumu lation by ascites tumor cells has no effect on transport of proline, glycine, his tidine, or methionine by intestine of the golden hamster (73). Further evi dence of metabolic intervention is that methionine reduces the rate of ab sorption of histidine (74).…”