PLASMA OXYTOCIN, ARGININE VASOPRESSIN AND ATRIAL NATRIURETIC PEPTIDE RESPONSES TO INSULIN-INDUCED HYPOGLYCAEMIA IN MAN

The changes in blood glucose, plasma oxytocin, plasma vasopressin, plasma atrial natriuretic peptide, serum osmolality, haematocrit and blood pressure were measured in response to acute insulin-induced hypoglycaemia in six normal male subjects. After the i.v. administration of insulin (0.15 U/kg), plasma concentrations of oxytocin and vasopressin increased rapidly in all subjects and were maximal 15 min after the acute hypoglycaemic reaction (R). Haematocrit increased at the time of the hypoglycaemic reaction, but there was no change in serum osmolality. Systolic blood pressure rose and diastolic blood pressure fell, but mean arterial blood pressure remained unchanged. No changes were demonstrated in plasma concentrations of atrial natriuretic peptide. The release of oxytocin and vasopressin in response to acute hypoglycaemia in man is probably caused by stimulation of the posterior pituitary gland via hypothalamic activation, and not by stimulation of osmoreceptors or baroreceptors.