Distribution of catecholaminergic receptors in the rat's pancreas islet

The effects of noradrenaline, adrenaline, isoproterenol, dopamine, apomorphine and their blockers on biphasic insulin secretion induced by 0.3% glucose were observed by means of a modified Lacy's perifusion method. Noradrenaline and adrenaline completely inhibit biphasic insulin secretion, and their effects disappeared completely after pretreatment with phentolamine. Dopamine inhibited the first phase completely and inhibited the second phase partially, and the inhibitory action of the dopamine disappeared after the pretreatment with phentolamine or propranolol. Isoproterenol had no effect on glucose-induced insulin secretion, whereas after treatment with phentolamine, isoproterenol produced a first-phase type of response. Domperidone blocked the effect of dopamine on the suppression of the first phase response. Apomorphine produced the second phase suppression slightly. It was concluded that the sympathetic alpha receptor and DA1 was distributed on the B-cells, the sympathetic beta 2 receptors on the D-cell and the DA2 on the varicosity of the sympathetic beta 2 neuron.