title: Inotropic and chronotropic activity of berberine on isolated guinea pig atria.
abstract: The cardiac effects of berberine were studied in isolated right and left atrial preparations from guinea pigs. In spontaneously beating right atria, berberine (1 X 10(-5) -3 X 10(-4) M) caused bradycardia, which was not prevented by atropine (1 X 10(-7) M). Over the same concentration range, berberine increased developed force (dF) in left atria electrically driven at 1.5 Hz. This occurred in both untreated and reserpine-treated tissues as well as in the presence of 5 X 10(-7) M propranolol and 1 X 10(-5) M phentolamine. At a stimulation frequency of 1.5 Hz, left atrial responses to each concentration of berberine reached steady state in approximately 10 min. Concentrations of berberine greater than 3 X 10(-4) M depressed dF and increased resting tone until eventually the left atria failed to contract. Analysis of the effects of berberine on the contractile waveform of left atria showed a concentration-dependent increase in maximal positive dF/dt, maximal negative dF/dt, time to peak tension, and relaxation time. When maximal negative dF/dt was normalized for changes in dF (-dF/dt/dF), berberine showed inhibition of the relaxation process. Berberine had only slight effects on post-rest potentiation and paired pulse stimulation, but enhanced the response of left atria to increases in stimulation frequency. From these results, it appears that berberine has a unique profile of action in isolated guinea pig atrial tissue, showing both positive inotropic and negative chronotropic activity. Berberine produces its positive inotropic effect by enhancing both the force-velocity relationship and the duration of the active state.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: J E
authors.initials: JE
authors.lastname: Shaffer
mesh_terms: D000818:Animals; D001599:Berberine / Q000494:pharmacology*; D001600:Berberine Alkaloids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D004558:Electric Stimulation; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*
chemical_list: D001600:Berberine Alkaloids; D001599:Berberine; D002118:Calcium