Growth hormone pre-treatment combined with exogenous glutamine induced a postoperative shift from glucose to glutamine consumption in the gastrointestinal tract

Abstract

The aim of this study was to assess whether the protein sparing effects associated with administration of growth hormone (GH) and glutamine in the early post traumatic period deprive the gastrointestinal tract of substrates. Sixteen piglets were randomized to receive GH treatment ( n = 8) for 3 days prior to surgery whilst a control group ( n = 8) received no growth hormone. Organ fluxes of glucose, lactate, pyruvate, alanine and glutamine were measured at 1 and 5 h after surgery. An infusion of glutamine (36 μg/kg/min) was started after the first measurement in both groups. In the GH group (5 h after surgery), hindleg release of glutamine and alanine was found to be lower than in the control group, whilst intestinal glutamine uptake was higher and that of alanine was lower. Hepatic alanine uptake was reduced whilst hepatic glutamine exchange switched from uptake to release. Intestinal glucose consumption was lower in the GH group ( P < 0.05). It is concluded that GH pre-treatment in combination with exogenous glutamine administration induced a shift in gastrointestinal fuel selection which was associated with reduced glucose consumption and increased glutamine consumption. The effect of GH in inducing hepatic release of glutamine compensated for its effect on muscle which results in reduced peripheral glutamine release.