Effects of graded doses of somatostatin on gallbladder emptying and pancreatic enzyme output after oral glucose in man.

Effects of intravenous somatostatin on the secretion, motility and absorption in the upper gastrointestinal tract after 75 g oral glucose were examined in healthy subjects with a quantitative multiple indicator dilution method. This report deals with the effects on the gallbladder emptying and the pancreatic enzyme output. Intake of a hypertonic glucose solution induces rapid gallbladder emptying. After early peaks, both biliary and pancreatic enzyme outputs remain at a steady lower level to the end. Somatostatin, started 20 min before the oral load, inhibited dose-dependently the gallbladder emptying and pancreatic enzyme secretion. A maximal inhibition was attained by 1.5 microgram . min-1, and 0.05 microgram . min-1 somatostatin gave a significant 40% reduction. The inhibition persisted in the postinfusion period and was followed by delayed rebound outputs. The gallbladder emptying was completely arrested for variable periods of time, but the pancreatic enzyme secretion was never totally blocked. The promptly established arrest of the gallbladder differed from the slowly initiated inhibition of the gastric and intestinal propulsion. It is proposed that the multiple ways of action of somatostatin and different stimulatory levels contribute to the discrepancies. The study shows that somatostatin induces dose-dependent, long-lasting inhibitions of the biliary and pancreatic responses to oral glucose. The minimal effective dose was a hundred times lower than the dose tested in previous studies in man.