title: [Effects of tetrahydroprotoberberines on cytosolic free calcium in cultured rat single myocardial cells].
abstract: Effect of tetrahydroberberine (THB), l-tetrahydropalmatine (THP) and l-stepholidine (SPD) were supposed to be related to the blocking of calcium influx. In this paper, using Fura-2/AM and AR-CM-MIC cation measurement system, the effects of THB, THP and SPD on cytosolic free calcium ([Ca2+]i) in cultured rat single myocardial cells were examined and compared with verapamil (Ver). THB, THP and SPD (10-100 mumol.L-1) were found to increase resting [Ca2+]i gently, which was not depressed by tetrodotoxin. THB, THP and SPD (1-100 mumol.L-1) were also shown to inhibit the KCl-induced [Ca2+]i elevation, the IC50 values of THB and SPD were 50.9 (95% confidence limits: 18.5-140) mumol.L-1 and 23.5 (95% confidence limits 7.6-73.4) mumol.L-1, respectively. THB, THP and SPD 30 mumol.L-1 were also shown to inhibit the elevation of [Ca2+]i induced by high extracellular calcium and norepinephrine; but the inhibitory effects of these drugs were weaker than those of Ver. The three compounds showed no significant effect on ouabain induced [Ca2+]i increase. These results suggest that the inhibitory effects of THB, THP and SPD on [Ca2+]i in myocite by blocking voltage-dependent calcium channels were similar but inferior to Ver.
authors.affiliation: Department of Pharmacology, Nanjing Medical University.
authors.forename: X T
authors.initials: XT
authors.lastname: Li
authors.forename: Y L
authors.initials: YL
authors.lastname: Wang
authors.forename: J X
authors.initials: JX
authors.lastname: Wang
authors.forename: S J
authors.initials: SJ
authors.lastname: Yang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001599:Berberine / Q000031:analogs & derivatives / Q000494:pharmacology; D001600:Berberine Alkaloids / Q000494:pharmacology*; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002478:Cells, Cultured; D009206:Myocardium / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014700:Verapamil / Q000494:pharmacology
chemical_list: D001600:Berberine Alkaloids; D002121:Calcium Channel Blockers; D001599:Berberine; C010513:stepholidine; C014215:tetrahydropalmatine; D014700:Verapamil; D002118:Calcium; C004645:canadine