Somatostatin prevents the postoperative increases in plasma amino acid clearance and urea synthesis after elective cholecystectomy.

The importance of glucagon on postoperative changes in hepatic amino-nitrogen conversion were investigated in six patients undergoing elective cholecystectomy for uncomplicated gall stones. Patients were given infusions of somatostatin (bolus of 6 micrograms/kg followed by continuous infusion of 6 micrograms/kg/h) from induction of anaesthesia to the end of investigation, the first postoperative day (30 hours). Controls were 16 patients undergoing the same procedures omitting the somatostatin infusion. In all patients blood concentration and plasma clearance of total alpha-amino-nitrogen, and amino acid stimulated rate of urea synthesis were measured. Elective cholecystectomy decreased blood alpha-amino-nitrogen concentration from mean (SEM) 2.9 (0.2) to 2.4 (0.1) mmol/l (p < 0.05), increased the clearance of total alpha-amino-nitrogen from 5.2 (0.3) to 6.6 (0.3) ml/s (p < 0.05), and increased the rate of amino acid stimulated urea synthesis from 27 (1) to 37 (2) mumol/s (p < 0.05) pointing to increased hepatic removal of amino-nitrogen at expense of plasma amino-nitrogen. Infusion of somatostatin prevented increase of glucagon for 24 hours after surgery, and prevented the negative changes in postoperative nitrogen homeostasis resulting from the postoperative changes in hepatic nitrogen conversion, suggesting glucagon as mediator. The exact mechanism remains in doubt, however, because of the multiple effects of somatostatin.