Effect of infusion of salmon calcitonin on the secretion of somatostatin and gastrin in man.

In vitro and animal studies have pointed out complex interrelations between gastrointestinal hormones and calcitonin. To analyse the acute effects of calcitonin in more detail, patients undergoing surgery were infused intravenously with synthetic salmon calcitonin, a potent analog of the human hormone. Samples were taken after 0, 30 and 60 minutes from the hepatic, portal and a peripheral vein. Somatostatin and gastrin were determined by radioimmunoassay. The mean basal levels of somatostatin in peripheral and hepatic venous plasma (14.2 and 15.6 pg/ml) were significantly lower than in portal plasma (45.6 pg/ml), indicating effective removal by the liver. After infusion of calcitonin there was a general rise in somatostatin levels and an increase in the gradient between hepatic and portal blood. Basal gastrin levels were highest in the portal vein when compared intraindividually. The differences disappeared after calcitonin infusion with a concomitant systemic reduction of gastrin levels. Thus, calcitonin is able to stimulate the secretion of somatostatin from the gastrointestinal tract and does reduce gastrin secretion, possibly via the stimulation of somatostatin secretion.