The excretion of the enantiomorphs of amino‐acids

Crampton, R. F.; Smyth, David

doi:10.1113/jphysiol.1953.sp004974

Cited by 36 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other workers have shown that the normal kidney tubule distinguishes D-from L-aminoacids (17,18). The latter suggested (18) on the basis of clearance studies that some D-amino-acid passively diffused through the tubule back into the blood stream Our results do not suggest any passive diffusion of D-cystine in cystinuric subjects.…”

Section: Feeding Of L-arginine Hci L-lysine Hci Andcontrasting

confidence: 42%

The Pathogenesis of Cystinuria. II. Polarographic Studies of the Metabolism of Sulphur-Containing Amino-Acids

Dent¹,

Senior²,

Walshe³

1954

J. Clin. Invest.

View full text Add to dashboard Cite

The preceding paper (1) in this series describes some paper chromatographic and microbiological analyses of plasma and urine during acute experiments in which loading doses of cystine, cysteine, and methionine were given by mouth to normal and cystinuric subjects. Cysteine alone caused large rises in plasma cystine levels and urine outputs in both normal and cystinuric subjects. In all cases, urine output varied directly with plasma cystine levels, but in the cystinuric subjects the urine output was very much greater for any given plasma level than in the normal subject. The results were taken as strong evidence in favour of the renal theory of cystinuria, namely that the high cystine output of a cystinuric patient is due not to an innate inability to metabolize cystine or other sulphur-containing amino-acids but to a "low renal threshold" for cystine, presumably from defective tubular reabsorption. The methods of analysis used though highly specific qualitatively were not, however, considered sufficiently accurate quantitatively to enable renal clearances to be calculated.In this paper we have repeated in greater numbers experiments of the type described in the preceding paper (1) using an almost identical procedure for timing and collecting samples of plasma and urine. The cystine determinations, however, were done exclusively by polarography. This method, depending upon entirely different principles, is likely to be specific in the circumstances. There is no convincing evidence for the presence in these fluids (after deproteinization when necessary) of appreciable quantities of other substances which might interfere with the analysis owing to their containing .disulphide (-S-S-) or thiol

show abstract

Section: Feeding Of L-arginine Hci L-lysine Hci Andcontrasting

confidence: 42%

The Pathogenesis of Cystinuria. II. Polarographic Studies of the Metabolism of Sulphur-Containing Amino-Acids

Dent¹,

Senior²,

Walshe³

1954

J. Clin. Invest.

View full text Add to dashboard Cite

show abstract

“…d-Amino acids were chosen in this experiment because these amino acids may not be actively metabolized (Crampton and Smyth, 1953) nor used in protein construction. Although the saliva d-alanine and d-glutamate levels were high 30 min after the ingestion of the amino acids, the levels returned to near control levels 1.5 h after ingestion.…”

Section: Discussionmentioning

confidence: 99%

The presence of high concentrations of free d-amino acids in human saliva

et al. 2006

View full text Add to dashboard Cite

“…In all cases the quotient is greater than unity, showing that the L-enantiomorph is absorbed much more rapidly into the blood stream than the D-enantiomorph. Crampton & Smyth (1953) have produced evidence that the rates of diffusion of D-and L-alanine are of the same order, and thus the more rapid rate of absorption of the L-enantiomorph must be due to a selective stereochemically specific process in the intestinal mucosa.…”

Section: Resultsmentioning

confidence: 99%

“…The in vitro intestine preparation of Wiseman (1953) as modified by Smyth & Whaler (1953) was used. Crampton & Smyth (1953) have used this preparation to measure the rate of disappearance of D-and L-alanime from the lumen of the intestine. It was thought that measurement of the L/D quotient might be better made by estimating the amounts of D-and L-enantiomorphs appearing in the outer fluid when equal amounts were initially present in the inner fluid, as the quotient would then depend on only one measurement of each enantiomorph, and not on the difference between two measurements.…”

Section: Resultsmentioning

confidence: 99%

“…Effects of temperature on rates of absorption Some experiments were carried out to extend the observations of Crampton & Smyth (1953) and also to test the effect of temperature on the L/D quotient of the amino-acid absorbed in vivo. These in vivo experiments in which the intestine was cooled in situ were complicated by the fact that a lowering of temperature caused a great reduction in the movement of both enantiomorphs.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The intestinal absorption of amino‐acid enantiomorphs

Matthews¹,

Smyth²

1954

The Journal of Physiology

Self Cite

View full text Add to dashboard Cite

Gibson & Wiseman (1951) showed that when amino-acids were injected into the lumen of the intestine of the rat, the L-enantiomorph disappeared at a faster rate than the D-enantiomorph, and they postulated a stereochemically specific mechanism for the absorption of L-amino-acids. In support of this, Clarke, Gibson, Smyth & Wiseman (1951) showed that L-amino-acids also disappeared faster than D-amino-acids from the Thiry-Vella loop in the dog, and Wiseman (1953) showed with an in vitro technique that L-amino-acids could be transferred by the intestine against a concentration gradient, whereas D-amino-acids could not. While these experiments furnish strong evidence for the existence of a stereochemicaily specific mechanism for absorption of amino-acids from the intestine, they fail to supply any information about the concentration of the D-and L-amino-acids in the blood stream during absorption, and the present work was undertaken to investigate this aspect of the problem. Preliminary accounts of the results have been given by Matthews & Smyth (1952, 1953. METHODSThe experiments were done on cats anaesthetized with pentobarbitone sodium. The carotid artery was cannulated by the procedure described by Crampton & Smyth (1953), which enables blood to be collected from or introduced into the carotid artery with simultaneous measurement of the blood pressure. A loop of the intestine was selected near to the caecum and spread out so that the arterial and venous supply could be inspected. A part of the intestine drained by a suitable vein was chosen, and this section of intestine was cannulated, washed out with warm saline (0-9 % NaCI) and tied off at each end. The vein draining the loop was now prepared for cannulation without any interference with the blood flow. There was thus an isolated section of intestine about 30 cm long with intact blood supply, and so arranged that on cannulation of the vein draining the loop, the blood from this section of the intestine could be collected. The loop of intestine was arranged on a heated plate and protected with a Perspex cover, so that it could be kept at a temperature of 370 C, moistened with saline and inspected during the experiment.The animal was then heparinized and the blood pressure measured in the carotid artery. Blood (30-50 ml.) was withdrawn from the carotid artery till the blood pressure had fallen to about 50 mm of mercury. The object of this was to reduce the rate of blood flow. Although this must

show abstract

The excretion of the enantiomorphs of amino‐acids

Cited by 36 publications

References 11 publications

The Pathogenesis of Cystinuria. II. Polarographic Studies of the Metabolism of Sulphur-Containing Amino-Acids

The Pathogenesis of Cystinuria. II. Polarographic Studies of the Metabolism of Sulphur-Containing Amino-Acids

The presence of high concentrations of free d-amino acids in human saliva

The intestinal absorption of amino‐acid enantiomorphs

Contact Info

Product

Resources

About