Somatostatin 28: effects on exocrine pancreatic secretion in conscious dogs

The effect of somatostatin 28, a noval intestinal peptide containing somatostatin in its C-terminal portion, was tested on basal exocrine pancreatic secretion on conscious dogs and after stimulation by secretin (1 CU x kg-1 x hr-1), caerulein (37.5 ng x kg-1 x hr-1) or secretin (2 CU x kg-1 x hr-1) caerulein (37.5 ng x kg-1 x hr-1). We found differences in the inhibitory effect of somatostatin 28 on these three forms of stimulation. Bicarbonate secretion stimulated by secretin was inhibited only slightly by large doses of somatostatin 28, whereas small doses markedly inhibited stimulation by caerulein. Protein concentrations were inhibited only when secretin was the stimulant. Protein outputs to all forms of stimulation were inhibited. When compared with synthetic somatostatin 14, lower doses of somatostatin 28 were required to produce the same inhibitory effect on protein outputs stimulated by secretin alone and on volumes stimulated by caerulein alone.