Inhibition of nicotinic receptor-mediated catecholamine secretion by dryobalanops aromatica in bovine adrenal chromaffin cells |
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Authors: | Kyu-Suk Oh Tae-Ju Park Bo-Hwa Choi Dong-Kyu Lee Tae-Kyun Lee Kyong-Tai Kim |
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Institution: | College of Oriental Medicine, Dongguk University, Kyongju, Korea. |
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Abstract: | Effect of the aqueous extract from a medicinal plant Dryobalanops aromatica(Dipterocarpaceae) on catecholamine secretion was investigated in bovine adrenal chromaffin cells. The aqueous extract inhibited (3)H]norepinephrine ((3)H]NE) secretion induced by 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), a nicotinic acetylcholine receptor (nAChR) agonist, with a half-maximal inhibitory concentration (IC(50)) of 8.4 +/- 1.7 microgml(-1). Increases in cytosolic calcium (Ca(2+)](i)) and sodium (Na(+)](i)) induced by DMPP were also inhibited by the extract. However, the binding of (3)H]nicotine to nAChRs was not affected by the addition of the extract in receptor binding competition analysis, suggesting that active components in the extract and nicotine do not share the binding site in the nAChR. On the other hand, Ca(2+)](i)increases induced by high K(+), ionomycin, bradykinin, angiotensin II, and thapsigargin were not inhibited by the extract. The data suggest that the extract from D. aromatica specifically inhibits catecholamine secretion by blocking nAChR in a noncompetitive manner. |
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Keywords: | Dryobalanops aromatica catecholamine secretion nicotinic receptor |
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