Nicotonic and muscarinic components in acetylcholine stimulation of porcine adrenal medullary cells

Abstract

Adrenal medullary chromaffin cells secrete catecholamines (CA) in response to cholinergic receptor activation by acetylcholine (ACh) released from splacnic nerve terminals. In cultured bovine chromaffin cells nicotinic receptors play a preponderant (> 90%) role in the control of CA release. By contrast, we found and report here that up to 40% of the ACh-evoked CA secretion from cultured porcine chromaffin cells can be associated with muscarinic receptor activation. The following results support our belief that in porcine adrenal medullary cells ACh (100 μM) evoked CA secretion is mediated by both nicotinic and muscarinic cholinergic receptors. 1) Hexamethonium (100 μM), a nicotinic receptor antagonist, inhibited ACh-induced CA secretion to ca. 40% of the control release and atropine (1 μM), a muscarinic receptor antagonist, inhibited to ca. 60% of the control value. 2) We also found that ACh(100 μM) evoked intracellular Ca2+ concentration ([Ca2+](i)) rise was inhibited by these recepto