| pubmed-article:11596211 | pubmed:abstractText | In order to verify the inotropic effect of berberine (Ber) on myocardial tissues, the effect of Ber on cytosolic free calcium [Ca2+]i in cultured rat single myocardial cells were examined by using Fura-2/AM and AR-CM-MIC cation measurement system. Ber (10-400 mumol.L-1) was found to increase the resting [Ca2+]i and saturate at about 200 mumol.L-1. The [Ca2+]i increase was not depressed by atropine, phentolamine, propranolol and tetrodotoxin, but was inhibited by verapamil (Ver) 3 mumol.L-1 or CoCl2 10 mmol.L-1. The [Ca2+]i increase induced by Ber (30 mumol.L-1) added to stimulating agents as KCl, CaCl2, NE or Oua was stronger than that induced by stimulating agents only and Ver 3 mumol.L-1 still showed inhibitory effects on the [Ca2+]i increase. Under Ca(2+)-free or Ca(2+)-, K+, Na(+)-free conditions, Ber (30-200 mumol.L-1) still showed ascending effects on [Ca2+]i, and Ver 3 mumol.L-1 only inhibited the Ber effects in Ca(2+)-free condition. The results suggest that Ber might induce moderate [Ca2+]i increase via Ca2+ influx and intracellular Ca2+ release, and show positive inotropic effect. | lld:pubmed |
