Journal
EUROPEAN JOURNAL OF PHARMACOLOGY
Volume 446, Issue 1-3, Pages 83-87Publisher
ELSEVIER
DOI: 10.1016/S0014-2999(02)01819-8
Keywords
nicotine; adrenaline; noradrenaline; adrenal gland; (rat); nicotinic receptor
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We tried to characterize nicotinic acetylcholine receptors involved in the release of catecholamines from the rat adrenal gland. The isolated adrenal gland was retrogradely perfused via the adrenal vein with Krebs-Ringer solution at a flow rate of 0.5 ml/min. Endogenous catecholamines, adrenaline and noradrenaline, released into the perfusate were electrochemically measured using high-performance liquid chromatography. (-)-Nicotine (3 x 10(-6)-3 x 10(-5) M) evoked the release of catecholamines (adrenaline noradrenaline) in a concentration-dependent manner. The (-)-nicotine (10(-5) M)-induced release of catecholamines was effectively attenuated by mecamylamine (10(-7) and 10(-6) M) (a relatively selective antagonist of alpha3beta4 nicotinic receptors), but not influenced by alpha-bungarotoxin (3 x 10(-7) M) (an antagonist of alpha7 nicotinic receptors) and dihydro-beta-erythroidine (10(-5) M) (a relatively selective antagonist of alpha4beta2 nicotinic receptors). (+/-)-Epibatidine (3 x 10(-7) and 10(-6) M) (a non-selective nicotinic receptor agonist), ( -)-cytisine (10(-5) and 10(-4) M) (an agonist of beta4 nicotinic receptors) and (+/-)-2-(3-pyridinyl)-1-azabicyclo(2.2.2)octane (RJR-2429) (10(-5) M) (a putative agonist of alpha3beta4 nicotinic receptors) effectively evoked the release of catecholamines (adrenaline noradrenaline), while (E)-N-methyl-4-(3-pyridinyl)-3-butene-1-amine (RJR-2403) (up to 10(-4) M) (a selective agonist of alpha4beta2 nicotinic receptors) had no effect. The efficacies of these agonists are as follows: (+/-) epibatidine much greater than RJR-2429 > (-)-cytisine>(-)-nicotine much greater than RJR-2403. These results suggest that alpha3beta4 nicotinic receptors are involved in the release of catecholamines from the rat adrenal gland. (C) 2002 Elsevier Science B.V. All rights reserved.
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