[Effects of praeruptorin-C on cytosolic free calcium in cultured rat heart cells].
The negative inotropic effect of Pra-C was supposed to be related to the blocking of extracellular calcium influx but direct evidence is not known. We, therefore, examined the effects of Pra-C on [Ca2+]i in isolated rat ventricular myocytes using the fluorescent Ca(2+)-indicator Fura-2/AM. It was found that Pra-C inhibited the elevation of [Ca2+]i induced by potassium-depolarization, high extracellular calcium and calcium agonist Bay K 8644 in a dose-dependent manner. At 1.0 mumol.L-1, it decreased the [Ca2+]i at the presence of 75 mmol.L-1 KCl, 10 mol.L-1 CaCl and 3 mumol.L-1 Bay K 8644 by 50, 31 and 42% respectively. No significant effect on ouabain evoked [Ca2+]i increase was found, showing that it does not affect sarcolemmal Na(+)-Ca2+ exchange. These results further indicate that Pra-C may decrease the [Ca2+]i of myocyte by blocking voltage-dependent calcium channels.
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Institute of Traditional Chinese Medicine and Pharmacy, Nanjing College of Traditional Chinese Medicine.
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D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000037:antagonists & inhibitors; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002122:Calcium Chloride / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D003374:Coumarins / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D011189:Potassium Chloride / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar
D002121:Calcium Channel Blockers; D003374:Coumarins; D011189:Potassium Chloride; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C058808:praeruptorin C; D002122:Calcium Chloride; D002118:Calcium