[Effects of noradrenaline and isoproterenol on the insulin secretion from the rat pancreas perfused isolatedly in situ].

Effects of noradrenaline and isoproterenol on insulin secretion in rat pancreas have been studied by means of the in situ perfusion method described previously. Noradrenaline: The insulin secretion from the rat pancreas perfused with the high glucose buffer decreases after the administration of 1 microgram/0.1 ml of noradrenaline into the perfusion fluid. These noradrenaline-induced hyposecretions can be reversed by pretreatment with phentolamine (10 micrograms/ml), while they are potentiated after propranolol (10 micrograms/ml) pretreatment. Isoproterenol: The insulin secretion from the rat pancreas perfused with the same buffer increases after the administration of 1 microgram/0.1 ml of isoproterenol into the perfusion fluid. These isoproterenol-induced hypersecretions are found to be potentiated after pretreatment with phentolamine or propranolol, and atropine (100 micrograms/ml) pretreatment does not produce any changes in the isoproterenol-induced hypersecretion. These results suggest that the beta-receptors on the B-cells stimulate the insulin secretion and the beta-receptors on the D-cells decrease them. This communication gives a short discussion of whether alpha-receptors may be on D-cells or not.