Contribution of the pancreas to circulating somatostatin-like immunoreactivity in the normal dog.

Abstract

A~bstract. These studies were performed to assess the contribution of the pancreas to the somatostatinlike immunoreactivity (SLI) circulating in arterial and portal venous plasma. Basal SLI concentrations in arterial, pancreatic venous, and portal venous plasma were 95±9, 277±32, and 130±12 pg/mi, (+±SEM), respectively. Measurement of pancreatic and portal venous blood flow (5±1 vs. 365±46 ml/min) and hematocrit allowed calculation of net, base-line SLI output from the right lobe of the pancreas (521±104 pg/min) and from the gastrointestinal tract (8,088±1,487 pg/min), which suggested that the contribution of the pancreas to circulating SLI was minor when the D cells were not stimulated. To stimulate the secretion of SLI from both pancreatic and nonpancreatic sources, isoproterenol, a beta-adrenergic agonist, was infused intravenously for 1 h into six anesthetized dogs. Arterial SLI increased by 52±9 pg/ml; superior pancreatico-duodenal venous SLI increased by 380±95 pg/ml; portal venous SLI increased by 134±14 pg/ml. Pancreatic venous blood flow remained unchanged at 5±1 ml/min, but portal venous blood flow increased to 522±62 ml/min. SLI Volume 73, January 1984, 216-223 organ blood flow, can give a false impression ofthe organ's contributions of circulating SLI. To verify that the contribution of the pancreas was negligible, six dogs received an acute pancreatectomy and then an intravenous infusion of isoproterenol at the same rate. In these dogs, both the base-line level of SLI in arterial plasma (109±12 pg/ml) and the increment during isoproterenol (56±8 pg/ ml) were similar to those of normal dogs. Likewise, in pancreatectomized dogs both the base-line level of SLI in portal venous plasma (129±16 pg/ml) and the increment during isoproterenol (174±34 pg/ml) were similar to those of normal dogs. We conclude that, in normal dogs, the pancreas makes a negligible contribution to the basal and stimulated level of SLI in arterial and portal venous plasma and therefore that these levels should not be used as an index of secretory activity of the pancreatic D cells.

Induction and Management of Diabetes Mellitus in the Pig

“…This suggests that the pancreas makes little contribution to circulating somatostatin levels in the pig. Similar findings have been reported for the dog (Taborsky and Ensinck, 1984).…”

Circulating prosomatostatin-derived peptides. Differential responses to food ingestion.

“…Levels Table I. Concentrations of peptides in fraction 1 43 In Fig. 7 are displayed the values for the various peptides in peripheral plasma from patients in whom the stomach or pancreas or both had been resected.…”

“…However, the pancreas contributes less than do either stomach or intestine (43,44) and as the amount of S-28 in rat pancreas and canine stomach are small and unlikely to be intermediates in the processing to S-14 (24,26), it is probable that neither of these organs are major sources of circulating S-28. This is in keeping with our findings in pancreatectomized patients in whom levels of S-28 and S-14/S-13 were similar to those of normal men during basal and postprandial phases.…”

Function and expression of somatostatin receptors of the endocrine pancreas

“…There are two major circulating SST-isoforms, which consist of 14 and 28 amino acids, respectively, which are processed from a common precursor protein in a cell-and tissue-specific pattern (Brazeau et al, 1973;Burgus et al, 1973;Pradayrol et al, 1980). In the adult, the primary secretory product of pancreatic D-cells is SST-14 (Noe 1981;Patel et al, 1981), which contributes to less than 5% of circulating SST (Taborsky, Jr. and Ensinck 1984). In the fasting state plasma concentration of SST is low (30-100 pg/ml) and increases by approximately two-fold in the postprandial state (Binimelis et al, 1987).…”