Renal mitochondrial glutamine transport and metabolism: studies with a rapid-mixing, rapid-filtration technique

Publisher Website
Google Scholar
Abstract
A rapid-mixing, rapid-filtration method was developed to measure initial rates of accumulation of glutamine transport products (Gln-TP) in the matrix of isolated rat renal mitochondria. Gln-TP accumulation was linear for only a few seconds and approached a steady state by 30 s. Physiological concentrations of .alpha.-ketoglutarate produced marked inhibition of Gln-TP accumulation. The Km glutamine of the accumulation process was 2.7 mM in the absence of .alpha.-ketoglutarate and 5.4 mM when 0.3 mM of the keto acid was present in the incubation medium. Vmax was not significantly altered by .alpha.-ketoglutarate. .alpha.-Ketoglutarate inhibits mitochondrial glutamine metabolism by decreasing the affinity, but not the capacity, of the accumulation process for the amino acid. Accumulation of Gln-TP in the mitochondrial matrix was also inhibited by agents that facilitate the movement of H+ across the inner membrane: uncouplers of oxidative phosphorylation and the antibiotic nigericin. The accumulation process may be linked to the proton gradient (or proton uptake) that normally exists across the inner mitochondrial membrane.

This publication has 9 references indexed in Scilit: