The present study was undertaken to determine if acute stress induced by exposure to
ether resulted in the presence of beta-cell-tropic factors in rat plasma and if this insulinotropic activity was increased by
pertussis toxin. Rats pretreated with
pertussis toxin (5 micrograms/kg, 5 days previously) showed marked
hyperinsulinemia, but only after exposure to
ether before blood sampling. This
hyperinsulinemia was not modified by adrenal demedullation. Effects on insulin secretion were assessed by incubation of plasma (diluted with Krebs
buffer) with
collagenase-isolated rat pancreatic islets. When blood was collected by
decapitation from normal rats, the subsequently prepared plasma (12.5% to 50%) profoundly inhibited
insulin release from rat isolated islets. This inhibition was probably mediated by
catecholamines, since it was not seen with plasma from adrenal-demedullated rats and was prevented by alpha 2-adrenoceptor-blocking drugs. Plasma from adrenal-demedullated,
pertussis toxin-treated rats stimulated insulin secretion (by 60%) when the donor rats had been exposed to
ether before blood sampling. It is suggested that stress may result in the presence of circulating beta-cell-tropic factors, which may contribute to the acute stress-induced
hyperinsulinemia seen in
pertussis toxin-treated animals.