Recovery of impaired gluconeogenesis in kidney-cortex tubules of gentamicin-treated rabbits.

Rabbits were given gentamicin over a period of 10 days. At 1, 3, 5 and 10 days renal proximal tubules were isolated and glucose synthesis from several substrates was measured. A relationship between the inhibition of renal gluconeogenesis, accompanied by a decline of both pyruvate carboxylase and phosphoenopyruvate carboxykinase (PEPCK) activities, and an increased gentamicin level in kidney-cortex was noticed after 5 days of therapy. Both the rates of glucose formation from various substrates as well as pyruvate carboxylase and the cytosolic PEPCK activity recovered fully within 3 weeks after cessation of antibiotic treatment while an increase of activity of the mitochondrial PEPCK occurred during chronic administration of the drug for 10 days. It is concluded, that gentamicin-induced inhibition of gluconeogenesis is one of the events occurring during complex action of this drug on renal cortex.