Ginsenoside-rg3 enhances some antihypertensive agents-induced inhibition of adrenal catecholamine secretion

Objective: The present study was designed to examine the influence of ginsenoside-Rg3 (Rg3), one of panaxadiol-type saponins, which is isolated from Korean Panax ginseng, in some antihypertensive agents-induced inhibition on the secretion of catecholamines (CA) from the perfused rat adrenal medullae. Design and method: The adrenal gland was isolated and perfused with Krebs-bicarbonate. CA was measured directly by using the fluorospectrophotometer. Results: Ginsenoside-Rg3 (3∼30 μM) during perfusion into an adrenal vein for 90 min significantly inhibited the CA secretion evoked by acetylcholine (ACh). Also, olmesartan (AT1 receptor blocker, 15 μM), simvastatin (an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, 60 μM), enalapril (an inhibitor of angiotensin converting enzyme, 150 μM), and cilnidipine (a voltage-dependent L-type Ca2+ channel blocker, 3 μM) significantly reduced the CA secretion evoked by ACh and angiotensin II (Ang II), respectively. In the simultaneous presence of ginsenoside-Rg3 (10 μM) along with four antihypertensive agents (olmesartan, enalapril, simvastatin or cilnidipine), the CA secretion evoked by ACh and Ang II was more strongly inhibited compared with that of each antihypertensive agent-treatment alone. Conclusions: Collectively, these results demonstrate that ginsenoside-Rg3 as well as antihypertensive agents can inhibit the CA secretion evoked by activation of both cholinergic and AT1 receptors from the perfused rat adrenal medulla. When this ginsenoside-Rg3 was used in combination with different antihypertensive agents, their effects of antihypertensive agents on reduction of adrenal CA secretion were significantly enhanced, which may also be clinically beneficial for the treatment of cardiovascular diseases.