The nervous control of rat somatostatin, glucagon and insulin secretions.

: Somatostatin-like-immunoreactivity (SLI), immunoreactive insulin (IRI), glucagon (IRG) and catecholamine concentrations were measured in rat portal plasma during electrical stimulation of the vagus and splanchnic nerves, and during experimentally-induced hypovolaemia and hypoxaemia. Blood pressure, arterial gases and pH were monitored and hepatic blood flow was estimated (EHBF). Stimulation of the vagus nerves induced an increase in IRG and IRI concentrations, but had different influences on SLI level according to the concomitant experimental conditions. Stimulation of the left splanchnic nerve induced a sharp rise in SLI, IRG and catecholamine concentrations, whereas IRI level decreased hypovolaemia and hypoxaemia. Phentolamine treatment augmented the basal IRI, IRG and SLI concentrations. It did not suppress the hypovolaemia-induced rise of IRG and SLI concentrations, but unmasked a strong IRI release. By contrast, propranolol and atropine reduced significantly the A and D cell responses to acute hypovolaemia. These results are consistent with a profound influence of pancreatic nerves on A, B and D cell functions, which should be taken into account for interpretation of results during in vivo experiments.