title: Gintonin facilitates catecholamine secretion from the perfused adrenal medulla.
abstract: The present study was designed to investigate the characteristics of gintonin, one of components isolated from Korean Ginseng on secretion of catecholamines (CA) from the isolated perfused model of rat adrenal gland and to clarify its mechanism of action. Gintonin (1 to 30 µg/ml), perfused into an adrenal vein, markedly increased the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. The gintonin-evoked CA secretion was greatly inhibited in the presence of chlorisondamine (1 µM, an autonomic ganglionic bloker), pirenzepine (2 µM, a muscarinic M1receptor antagonist), Ki14625 (10 µM, an LPA1/3receptor antagonist), amiloride (1 mM, an inhibitor of Na+/Ca2+exchanger), a nicardipine (1 µM, a voltage-dependent Ca2+channel blocker), TMB-8 (1 µM, an intracellular Ca2+antagonist), and perfusion of Ca2+-free Krebs solution with 5mM EGTA (a Ca2+chelater), while was not affected by sodium nitroprusside (100 µM, a nitrosovasodialtor). Interestingly, LPA (0.3~3 µM, an LPA receptor agonist) also dose-dependently enhanced the CA secretion from the adrenal medulla, but this facilitatory effect of LPA was greatly inhibited in the presence of Ki 14625 (10 µM). Moreover, acetylcholine (AC)-evoked CA secretion was greatly potentiated during the perfusion of gintonin (3 µg/ml). Taken together, these results demonstrate the first evidence that gintonin increases the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. This facilitatory effect of gintonin seems to be associated with activation of LPA- and cholinergic-receptors, which are relevant to the cytoplasmic Ca2+increase by stimulation of the Ca2+influx as well as by the inhibition of Ca2+uptake into the cytoplasmic Ca2+stores, without the increased nitric oxide (NO). Based on these results, it is thought that gintonin, one of ginseng components, can elevate the CA secretion from adrenal medulla by regulating the Ca2+mobilization for exocytosis, suggesting facilitation of cardiovascular system. Also, these findings show that gintonin might be at least one of ginseng-induced hypertensive components.
authors.affiliation: Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul 05029, Korea.
authors.forename: Seung-Yeol
authors.initials: SY
authors.lastname: Na
authors.affiliation: Department of Internal Medicine, School of Medicine, Boramae Seoul National University, Seoul 07061, Korea.
authors.forename: Ki-Hwan
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Leisure & Sport, College of Public Health & Welfare, Dongshin University, Naju 58245, Korea.
authors.forename: Mi-Sung
authors.initials: MS
authors.lastname: Choi
authors.affiliation: Department of Psychiatry, College of Medicine, Chosun University, Gwangju 61452, Korea.
authors.forename: Kang-Su
authors.initials: KS
authors.lastname: Ha
authors.affiliation: Department of Pharmacology, College of Medicine, Chosun University, Gwangju 61452, Korea.
authors.forename: Dong-Yoon
authors.initials: DY
authors.lastname: Lim
keywords: Adrenal medulla; Catecholamine secretion; Gintonin; Hypertensive component; LPA receptor