An alanine infusion (90 mg/kg/h) for eight hours was administered to seven patients after cholecystectomy in order to investigate the influence of elevated plasma alanine levels on the postoperative metabolism. The following metabolits and hormone concentrations were analysed in plasma: glucose, urea, free fatty acids, ketone bodies, amino acids, insulin and glucagon. Compared to the pre-infusion values on the 1. postoperative day after an overnight fasting, the following changes were monitored. The plasma glucose concentrations reached a maximum after four hours of infusion (p<0.05). Of the amino acids, significant elevated levels were found for alanine (300%, p<0.001), glutamine (36%, p<0.05), and α-aminobutyrate (61%, p<0.01). The free fatty acids and ketone bodies concentrations decreased immediately after the onset of the infusion of alanine (p<0.05), and increased again during the last four hours of infusion. The secretion of insulin and also the secretion of glucagon were stimulated by the increased alanine levels. The stimulation of insulin reached a maximum after only five minutes, but the glucagon levels increased continously until the end of the infusion. During the administration of alanine a nitrogen homeostase was achieved, which was a significant improvement (p<0.001) when compared to saline infusions before and after the alanine infusion. Conclusions: (1) Postoperative increased plasma levels of alanine stimulate gluconeognesis and reduce the plasma levels of lipolytic metabolites. The induced stimulation of insulin and glucagon is dependent on the duration of the alanine infusion for during extended infusion of alanine the insulin stimulation diminishes while the glucagon secretion continously increases. (2) Alanine is a potent anabolic substrate in the immediate postoperative situation.
- Postoperative metabolism
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