Influence of somatostatin on splanchnic glucose metabolism in postabsorptive and 60-hour fasted humans.
Cyclic somatostatin was administered intravenously (10 mug/min for 60 min) to 10 healthy overnight fasted (postabsorptive) subjects and to 5 healthy 60-h fasted subjects. In both groups, arterial insulin and glucagon fell 50% and splanchnic release of these hormones was inhibited. In the overnight fasted subjects splanchnic glucose output fell 70%, splanchnic uptake of lactate and pyruvate was unchanged, alanine uptake fell by 25%, and glycerol uptake rose more than twofold in parallel with an increase in arterial glycerol. In the 60-h fasted group splanchnic glucose output was less than 40% of that observed in the overnight fasted subjects. Somatostatin led to a further decrease (--70%) in glucose production. Splanchnic uptake of lactate and pyruvate fell by 30-40%, amino acid uptake was unchanged, while uptake of glycerol rose fivefold. Total uptake of glucose precursors thus exceeded the simultaneous glucose output by more than 200%. Splanchnic uptake of FFA rose fourfold during somatostatin while output of beta-hydroxybutyrate increased by 75%. Estimated hepatic blood flow fell 25-35% and returned to base line as soon as the somatostatin infusion ended. It is concluded that (a) somatostatin-induced hypoglucagonemia results in inhibition of splanchnic glucose output in glycogen-depleted, 60-h fasted subjects as well as in postabsorptive subjects, indicating an effect of glucagon on hepatic gluconeogenesis as well as glycogenolysis; (b) the glucagonsensitive step(s) in gluconeogenesis affected by somatostatin involves primarily intra-hepatic disposal rather than net hepatic uptake of glucose precursors; (c) splanchnic uptake of fatty acids and ketone output are increased in the face of combined insulin and glucagon deficiency; and (d) diminished splanchnic blood flow may contribute to some of the effects of somatostatin on splanchnic metabolism.
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005943:Gluconeogenesis; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000096:biosynthesis; D006801:Humans; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011773:Pyruvates / Q000097:blood; D013004:Somatostatin / Q000494:pharmacology*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007773:Lactates; D011773:Pyruvates; D013004:Somatostatin; D006003:Glycogen; D005934:Glucagon; D005947:Glucose