title: Arecoline inhibits catecholamine release from perfused rat adrenal gland.
abstract: OBJECTIVE
  To study the effect of arecoline, an alkaloid isolated from Areca catechu, on the secretion of catecholamines (CA) evoked by cholinergic agonists and the membrane depolarizer from isolated perfused rat adrenal gland.
  
  
  METHODS
  Adrenal glands were isolated from male Sprague-Dawley rats. The adrenal glands were perfused with Krebs bicarbonate solution by means of a peristaltic pump. The CA content of the perfusate was measured directly using the fluorometric method.
  
  
  RESULTS
  Arecoline (0.1-1.0 mmol/L) perfused into an adrenal vein for 60 min produced dose- and time-dependent inhibition in CA secretory responses evoked by acetylcholine (ACh) (5.32 mmol/L), 1.1-dimethyl-4-phenyl piperazinium iodide (DMPP) (100 micromol/L for 2 min) and 3-(m-choloro-phenyl-carbamoyl-oxy)-2-butynyl trimethyl ammonium chloride (McN-A-343) (100 micromol/L for 2 min). However, lower doses of arecoline did not affect CA secretion of high K(+) (56 mmol/L); higher doses greatly reduced CA secretion of high K(+). Arecoline also failed to affect basal catecholamine output. Furthermore, in adrenal glands loaded with arecoline (0.3 mmol/L), CA secretory response evoked by Bay-K-8644 (10 micromol/L), an activator of L-type Ca(2+) channels, was markedly inhibited, whereas CA secretion by cyclopiazonic acid (10 micromol/L), an inhibitor of cytoplasmic Ca(2+)-ATPase, was not affected. Nicotine (30 micromol/L), which was perfused into the adrenal gland for 60 min, however, initially enhanced ACh-evoked CA secretory responses. As time elapsed, these responses became more inhibited, whereas the initially enhanced high K(+)-evoked CA release diminished. CA secretion evoked by DMPP and McN-A-343 was significantly depressed in the presence of nicotine.
  
  
  CONCLUSIONS
  Arecoline dose-dependently inhibits CA secretion from isolated perfused rat adrenal gland evoked by activation of cholinergic receptors. At lower doses arecoline does not inhibit CA secretion through membrane depolarization, but at larger doses it does. This inhibitory effect of arecoline may be mediated by blocking the calcium influx into the rat adrenal medullary chromaffin cells without the inhibition of Ca(2+) release from the cytoplasmic calcium store. There seems to be a difference in the mode of action of nicotine and arecoline in rat adrenomedullary CA secretion.
authors.affiliation: Department of Pharmacology, College of Medicine, Chosun University, Gwangju, Korea. dylim@chosun.ac.kr
authors.forename: Dong-yoon
authors.initials: DY
authors.lastname: Lim
authors.forename: Il-sik
authors.initials: IS
authors.lastname: Kim
mesh_terms: D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride / Q000494:pharmacology; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001115:Arecoline / Q000494:pharmacology*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002395:Catecholamines / Q000378:metabolism*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D010477:Perfusion; D051381:Rats
chemical_list: D002120:Calcium Channel Agonists; D002395:Catecholamines; D018679:Cholinergic Agonists; D007211:Indoles; D018722:Nicotinic Agonists; D001115:Arecoline; D004246:Dimethylphenylpiperazinium Iodide; D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride; D009538:Nicotine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000252:Calcium-Transporting ATPases; D000109:Acetylcholine; C000543:cyclopiazonic acid