Preferential transference of amino‐acids from amino‐acid mixtures by sacs of everted small intestine of the golden hamster (Mesocricetus auratus)

Abstract

The ability of the small intestine to transfer amino-acids against a concentration gradient has been demonstrated by a number of investigators in the past few years (Wiseman, 1953;Agar, Hird & Sidhu, 1953;Smyth & Whaler, 1953;Wilson & Wiseman, 1954). The results of those investigations have shown that an active mechanism exists for the absorption of certain L-amino-acids but not for their D-forms. The L-amino-acids which those workers showed to be actively transferred by the small intestine of the rat are alanine, phenylalanine, methionine, histidine and isoleucine, but the L-forms of glutamic acid and aspartic acid are not (Wiseman, 1953). In the present investigation the method described by Wilson & Wiseman (1954) has been used to study the transference of glycine and the L-forms of proline, histidine, methionine, lysine and ornithine by sacs of everted small intestine of the hamster when these amino-acids were present singly and in pairs. The results show that when only one amino-acid was present L-proline, L-histidine, L-methionine, and glycine were readily transferred against a concentration gradient but L-lysine and L-ornithine were not. The results of the experiments in which pairs of amino-acids were used show that amino-acids for which a mechanism for active transfer exists compete with each other for that mechanism. On the basis of their effectiveness as inhibitors the order of affinity for the 'carrier' part of such a mechanism is methionine, histidine, proline and glycine (methionine appearing to have an affinity of roughly 20 times that of proline). Those amino-acids which when present alone were transferred at the lower rates (methionine and histidine) inhibited the transfer of the amino-acids transferred at the higher rates

Studies in Amino-acid Uptake by RD3 Sarcoma Cell Suspensions In Vitro

“…The ability of the RD3 sarcoma cells in suspension to take up amino-acids against a concentration gradient is well marked and the mechanism is active for the diamino-acids as well as for the mono-aminoacids. This is in contrast to the findings with hamster small intestine (Wiseman, 1955) which can transfer against a gradient only the mono-amino-acids but not the diamino-acids. The concentration ratios developed by the sarcoma cells and the hamster small intestine (Wiseman, 1955) are of the same order, although the intestine concentrates proline better than histidine, while the sarcoma cells concentrate histidine better than proline.…”

“…This is in contrast to the findings with hamster small intestine (Wiseman, 1955) which can transfer against a gradient only the mono-amino-acids but not the diamino-acids. The concentration ratios developed by the sarcoma cells and the hamster small intestine (Wiseman, 1955) are of the same order, although the intestine concentrates proline better than histidine, while the sarcoma cells concentrate histidine better than proline. With both these tissues it was found that poorly concentrated amino-acids act as better inhibitors than amino-acids which are well concentrated.…”

“…It is interesting to compare the results obtained for the RD3 sarcoma cell suspension with the results obtained by Wiseman (1955) for the hamster sniall intestine, the only norrtal tissue on which such a study has been made, although the mechanism for amino-acid uptake by intestine may differ to some degree from the mechanism in other normal cells. The ability of the RD3 sarcoma cells in suspension to take up amino-acids against a concentration gradient is well marked and the mechanism is active for the diamino-acids as well as for the mono-aminoacids.…”

“…If the mechanism differs appreciably for different tissues, it might well be possible to alter differentially the rate of growth of such tissues. Recently, it has been demonstrated (Wiseman, 1955) that the mnono-amino-mono-carboxylic acids compete for the concentrating mechanism of the hamster small intestine and that methionine completely inhibits the active uptake of glycine, L-proline, and L-histidine, when present in equimolecular amounts. When methionine is present at a twentieth the concentration of the proline, the ability of the intestine to concentrate proline is reduced by 50 per cent.…”

In Vitro Investigation of D- and Lenantiomer Synergistic Efects of Some Amino Acids

“…Later results (VISEMAN, 1953;AGAR et al, 1953;MATTHEWS and SMYTH, 1954) showed that transport of L-amino acids involves an active process and it was assumed that this did not apply to D-amino acids. On the other hand, JERVIS and SMYTH (1959) showed that competition between some Dhistidine and L-Met was possible using in vivo as well as in vitro techniques (WISEMAN, 1955). In the later work, JERVIS and SMYTH (1960) suggested that the transfer mechanism for L-Met has not been absolutely stereochemically specific and that D-Met is able to utilize this mechanism in vitro.…”