Glomerular filtration rate following administration of individual amino acids in conscious dogs.

Normal conscious dogs were given 100 mmol glycine, L-serine, L-alanine, L-threonine, L-proline, L-glutamic acid (50 mmol), L-aspartic acid and L-valine by stomach tube. All these amino acids increased glomerular filtration rate (G.F.R.). There was no increase in G.F.R. following L-cystine or D-serine. The intravenous infusion of L-proline, but not glycine, caused increase in G.F.R. The results suggest that the increase in G.F.R. was not due to a high plasma concentration of the individual amino acids but was related to the metabolism of amino acids with production of urea. It is postulated that after meat and during the metabolism of amino acids a factor is released which reaches and acts on the kidney to cause the increase in G.F.R.