Effect of secretin on plasma insulin and glucagon in man

To investigate the effect of physiological doses of secretin on pancreatic A and B cell functions, secretin was infused at a rate of 0.5, 1.0 and 2.0 clinical unit per kg body weight per hr into eight normal men for 30 min or 60 min after an over-night fast, and changes in plasma immunoreactive insulin (IRI) and glucagon immunoreactivity (GI) were measured while monitoring circulating secretin levels by a radioimmunoassay. During the infusion of secretin, the plasma immunoreactive secretin (IRS) levels rose to 140-390 pg/ml which was within a range of the physiological fluctuation in plasma secretin levels reported hitherto. No significant alteration of plasma IRI and GI levels could be demonstrated during these simulated physiologic infusions of secretin. These data suggest that, in humans, the physiological dose of secretin does not influence insulin and glucagon secretion from the pancreas in the basal state.