Differential secretion of glucagon-like and somatostatin-like immunoreactivity from the perfused eel pancreas in response to D-glucose.

The effects of D-glucose on the differential secretion of glucagon-like (GLI) and somatostatin-like (SLI) immunoreactivity have been studied using the perfused eel pancreas. During control perfusions with 2.7 mM glucose, basal secretion of GLI and SLI remained essentially stable for a period of 46 min, with an overall mean rate of 381 +/- 20 and 268 +/- 23 pg/min/100 mg dry wt of pancrease, respectively. An acute increase in perfusate glucose to 8.3, 16.7, and 33.3 mM resulted in a monophasic, dose-dependent decline in GLI secretion over 30 min. However, acute return of control glucose concentrations (2.7 mM) from 16.7 or 33.3 mM did not result in return of GLI to control levels, whereas from 8.3 mM glucose this was achieved slowly. By contrast, 8.3 mM glucose was without effect on SLI secretion, but at 16.7 and 33.3 mM a dose-dependent, biphasic pattern of release was evident, with a rapid return to control SLI levels during the terminal perfusion period with 2.7 mM glucose. The results suggest that the A and D cells of teleosts are sensitive to changes in glucose concentration, and, in terms of secretory profiles, release of GLI, and SLI, are qualitatively similar to those of mammals.