ISSN:
1432-2013
Keywords:
Amino acid transport
;
Renal tubule
;
Stereospecificity
;
Passive diffusion
;
Saturation kinetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Renal tubular reabsorption of glycine and of thel- andd-isomers of histidine, serine, phenylalamine, methionine, proline and cystine was investigated in vivo et situ by continuous microperfusion of single proximal convolutions of the rat kidney. In the case of glycine and thel-isomers, tubular reabsorption is saturable to a great extent. Thed-amino acids are reabsorbed much more slowly than the respectivel-forms. Furthermore in the case of methionine and perhaps also of proline, serine and phenylalanine, the fractional reabsorption decreases in the presence of high concentrations of thel-form. This indicates that thed-isomers also have a measurable affinity for the reabsorption mechanisms of the renal tubule. The very poor reabsorption ofd-amino acids in the presence of theirl-isomers indicates that simple passive diffusion plays only a relatively small role in tubular amino acid reabsorption. Permeability coefficients estimated from these findings are in the range from 1–5×10−7 cm2·s−1. These values are very similar to those found for other organic molecules of comparable molecular weights.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00581358
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