Glutamine metabolism in isolated dog kidney tubules: inhibition by dialysed albumin preparation.

The metabolic fate of L-glutamine (1 and 5 mM) was studied in isolated dog kidney tubules. At 1 and 5 mM substrate concentration, and after 60 min of incubation, glucose represented 40% and 25% of the glutamine removed; the glutamine unaccounted for (which was probably completely oxidized) represented about one-half and one-third of glutamine removal at 1 and 5 mM glutamine concentrations, respectively. Due to contaminating fatty acids, addition of dialysed bovine serum albumin (fraction V) greatly altered the metabolic fate of glutamine. This observation emphasizes the need for using albumin with great caution for experiments with kidney tubules.