Enteral glutamine modulates renal glutamine utilization

Enteral glutamine feeding effect on renal glutamine utilization was assessed from the perspective of gamma glutamyltransferase activity-dependent cellular glutamate modulation of phosphate-dependent glutaminase. After 4d, rats fed an elemental diet supplemented with glutamine exhibited a 2 1 % higher kidney glutamate content and 27% reduction in ammonium excretion, both P < 0.05. Glutamine removal from plasma was depressed 62% in the glutamine-fed group (324 +/- 155 vs. 780 +/- 154 nmol x min(-1) x 100 g body weight (-1), P < 0.05) despite an elevated arterial plasma glutamine load delivered to the kidney. Administration of acivicin, 36 mg/kg body weight, to glutamine-fed rats inhibited gamma glutamyltransferase > 90% and decreased kidney glutamate content 42%. This reduction in kidney glutamate was associated with a 3.3-fold enhancement in both glutamine extraction (474 +/- 184 to 1548 +/- 255 nmol x min(-1) x 100 g body weight (-1)) and ammonium excretion (295 +/- 30 to 978 +/- 96 nmol x min(-1) x 100 g body weight(-1)), both P < 0.01. These findings are consistent with enteral glutamine regulation of renal glutamine utilization through an elevation of the cellular glutamate level.