Amino acid reabsorption in the rat nephron. Free flow micropuncture study.
The concentration of nine endogenous free L-alpha-amino acids (ALA, LEU, ILE, PHE, TYR, LYS, GLU, PRO, GLY) and of taurine were determined simultaneously along the nephron of the rat kidney using free-flow micropuncture techniques without altering plasma amino acid concentration or kidney function. The amount of each amino acid was determined after dansylation (14C-labelled dansyl-chloride) in the micropuncture sample followed by thinlayer chromatography. The main site of reabsorption is the proximal tubule. After 15-20% of the proximal tubule length the bulk of reabsorption has taken place (18.9 plus or minus 3.4% S.E. of the filtered load remaining). Net reabsorption continues to a small but significant extent along the distal nephron (disal tubule and collecting duct). Reabsorption of taurine is less rapid (% remaining of filtered load at the early proximal tubule 37.0 plus or minus 4.6%). The transtubular concentration ratio of all amino acids except taurine follows a homogeneous course. Under the experimental conditions of this study no distction with respect to different systems of reabsorption "neutral", "basic", "acidic", "imino-glycine") could be made.
D000042:Absorption; D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D002855:Chromatography, Thin Layer; D005971:Glutamates / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D007532:Isoleucine / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008297:Male; D009399:Nephrons / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D051381:Rats / Q000378:metabolism*; D013654:Taurine / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D000596:Amino Acids; D002250:Carbon Radioisotopes; D005971:Glutamates; D007532:Isoleucine; D013654:Taurine; D014443:Tyrosine; D010649:Phenylalanine; D011392:Proline; D007930:Leucine; D008239:Lysine; D000409:Alanine; D005998:Glycine