Amino Nitrogen Metabolism Following Administration of Individual Amino Acids or Meat in Conscious Dogs

Abstract

Normal conscious dogs were given a meal of meat or doses of individual amino acids by stomach tube. The concentration of amino nitrogen in systemic arterial plasma and the rate of urea production both increased; the magnitude and time course of these increases varied with the individual amino acid administered. There was a relationship between the plasma amino nitrogen concentration and urea production following L‐serine, L‐alanine, L‐proline, dicarboxylic acids and L‐cystine similar to that obtained after meat ingestion. It is suggested that these amino acids were transaminated as rapidly as they were absorbed to produce an increase in a general pool of amino acids. Following L‐threonine, L‐valine, D‐serine and immediately after glycine, a small increase in urea production was accompanied by a large increase in plasma amino nitrogen concentration. It is suggested that these amino acids ‘escaped' transamination in the gut wall and liver and that the increase in plasma amino nitrogen was due to a high concentration of the individual amino acid administered.

Glomerular Filtration Rate Following Administration of Individual Amino Acids in Conscious Dogs

“…The experiments were those reported in the previous paper (Lee & Summerill, 1982) where the detailed protocol is given; here it is shown in Figs. 1 (1958) and threaded forward so that its tip was in or near the inferior vena cava.…”

“…Urine was analysed for creatinine and urea. The rate of urea production was estimated as described previously (O'Connor & Summerill, 1976b; Lee & Summerill, 1982 Summerill (1976a). It remained elevated for 5 h ( Fig.…”

“…Plasma was analysed for creatinine (O'Connor & Summerill, 1976a), urea (O'Connor & Summerill, 1976b) and amino nitrogen (Lee & Summerill, 1982) using auto-analyser methods previously described. Urine was analysed for creatinine and urea.…”

“…Glomerular filtration rate and amino nitrogen metabolism Values of plasma amino nitrogen concentration and the rate of urea production in these experiments are given in the previous paper (Lee & Summerill, 1982); they are plotted here in Fig. 4.…”

“…Changes in plasma amino nitrogen concentration and in urea production have been reported in the previous paper (Lee & Summerill, 1982). Values of G.F.R.…”