Muscarinic receptor modulation of release of [Met5]enkephalin immunoreactive material and catecholamines from the bovine adrenal gland

Abstract

Muscarinic receptor modulation of secretion from the adrenal medulla was studied using retrogradely perfused bovine tissue. Atropine, at a dose not affecting 1,1 dimethyl-4-phenylpiperizinium (DMPP)-stimulated release, inhibited the acetylcholine (ACh)-stimulated release of noradrenaline and [Met5]enkephalin-immunoreactive material (ME-IRM). DMPP-stimulated release of catecholamines and ME-IRM was potentiated by the addition of methacholine. Pilocarpine significantly potentiated the release of noradrenaline only. Methacholine, pilocarpine or muscarine, when infused alone, had no stimulatory affect on the basal release of ME-IRM. These findings suggest that the muscarinic receptors in the bovine adrenal medulla function by potentiating the release of ME-IRM and catecholamines induced by nicotinic receptor stimulation.