The effect of somatostatin on pancreatic endocrine responses mediated via the parasympathetic innervation in the conscious calf.

1. The effect of somatostatin on the responses to moderate insulin hypoglycaemia and to 2-deoxyglucose has been examined in 2--3 week-old calves with cut splanchnic nerves. 2. Intravenous infusions of somatostatin (150 p-mole . kg-1 . min-1) completely suppressed release of glucagon, pancreatic polypeptide (PP) and insulin from the pancreas in response to 2-deoxyglucose (1.1 m-mole/kg I.V.). 3. The same dose of somatostatin completely blocked the rise in plasma PP concentration that normally occurs in response to moderate insulin hypoglycaemia and significantly delayed the rise in plasma pancreatic glucagon concentration. The hypoglycaemic response to insulin was also found to be intensified by the administration of somatostatin. 4. It is concluded that each of the pancreatic neuroendocrine responses, that are now known to be mediated via the parasympathetic innervation, is suppressed in the presence of somatostatin in the young calf.