title: Preconditioning stimuli that augment chromaffin cell secretion.
abstract: We have investigated here whether a preconditioned stimulation of nicotinic and muscarinic receptors augmented the catecholamine release responses elicited by supramaximal 3-s pulses of 100 muM acetylcholine (100ACh) or 100 mM K(+) (100K(+)) applied to fast-perifused bovine adrenal chromaffin cells. Threshold concentrations of nicotine (1-3 muM) that caused only a tiny secretion did, however, augment the responses elicited by 100ACh or 100K(+) by 2- to 3.5-fold. This effect was suppressed by mecamylamine and by Ca(2+) deprivation, was developed with a half-time (t(1/2)) of 1 min, and was reversible. The nicotine effect was mimicked by threshold concentrations of ACh, choline, epibatidine, and oxotremorine-M but not by methacholine. Threshold concentrations of K(+) caused lesser potentiation of secretion compared with that of threshold nicotine. The data are compatible with an hypothesis implying 1) that continuous low-frequency sympathetic discharge places chromaffin cells at the adrenal gland in a permanent "hypersensitive" state; and 2) this allows an explosive secretion of catecholamines by high-frequency sympathetic discharge during stress.
authors.affiliation: Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Arzobispo Morcillo, 4. 28029 Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Tapia
authors.forename: Josefina
authors.initials: J
authors.lastname: García-Eguiagaray
authors.forename: Antonio G
authors.initials: AG
authors.lastname: García
authors.forename: Luis
authors.initials: L
authors.lastname: Gandía
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000311:Adrenal Glands / Q000294:innervation / Q000378:metabolism*; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism; D019439:Chromaffin Cells / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008464:Mecamylamine / Q000494:pharmacology; D016210:Methacholine Chloride / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D010095:Oxotremorine / Q000031:analogs & derivatives / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000378:metabolism; D013997:Time Factors
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D002395:Catecholamines; D018721:Muscarinic Agonists; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D011725:Pyridines; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D016210:Methacholine Chloride; D010095:Oxotremorine; C042743:oxotremorine M; D008464:Mecamylamine; D009538:Nicotine; C082748:epibatidine; D002794:Choline; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium