Extraction of somatostatin by the pancreas.

Pancreatic somatostatin has been postulated to be a paracrine or local modulator of islet function. Other locally released modulators, such as the sympathetic neurotransmitter norepinephrine, are known to be extracted by local tissues. Therefore, we hypothesized that somatostatin, in addition to being released from islet D-cells, might also be partially extracted by pancreatic tissue. To test the concept that the pancreas is capable of extracting somatostatin, exogenous somatostatin-14 was infused into the femoral vein, and the increments of somatostatin-like immunoreactivity in arterial plasma were compared to those in pancreatic venous plasma. Extraction of somatostatin-14 by the in situ dog pancreas averaged greater than 50%, whereas extraction of another pancreatic peptide, glucagon, was less than 17%. We conclude that the pancreas extracts significant quantities of exogenous somatostatin-14.