Developmental changes in pancreatic endocrine function in the young calf.

1. Pancreatic endocrine responses to 2-deoxyglucose (1.2 mmol/kg I.V.) known to be mediated via the autonomic innervation, have been investigated in calves 24 h after birth and the results compared with those obtained previously in older calves (Bloom, Edwards & Hardy, 1978). 2. Neurally mediated insulin release was found to be defective in the calf at 24 h, whereas the capacity to release both pancreatic glucagon and pancreatic polypeptide (PP) in response to 2-deoxyglucose appears to be fully developed at this age. 3. Both the release of glucagon and of PP from the pancreas which occurred under these conditions were suppressed by I.V. infusions of glucose (17 mumol . kg-1 . min-1) which raised the arterial plasma glucose concentration of unsuckled 24-h-old calves to the level normally encountered in suckled calves of the same age. 4. Closely similar changes in the haematocrit and plasma cortisol concentration occurred in both suckled and unsuckled 24-h-old calves in response to 2-deoxyglucose, suggesting that the intensity of the stimulus to the brain was equipotent and that glucose inhibits the release of glucagon and PP by a direct action on the alpha and PP cells respectively. 5. closely similar changes in plasma PP concentration were observed in suckled and unsuckled 24-h-old calves in response to 2-deoxyglucose, in spite of the higher plasma glucose concentration in the former group. It is concluded that the PP response is potentiated by some unidentified factor in suckled calves.