Potentiation by Higenaraine of the Aconitine-Induced Positive Chronotropic Effect in Isolated Right Atria of Mice: The Effects of Cholera Toxin, Forskolin and Pertussis Toxin

摘要

Aconitine and higenamine are the major cardioactive compounds obtained from processed aconite. The chronotropic interaction between these two compounds was investigated in isolated right atria of mice. Both aconitine and higenamine potentiated the action of the other. Practolol (lnivi), a selective /^-adrenergic antagonist, but not butoxamine (1 /jm), a /f2-adrenergic antagonist, blocked the potentiation by higenamine (5 nivi) of the aconitine-induced positive chronotropic effect and, at high concentrations (30 and 300 nivi) also shifted the aconitine concentration-response curves to the right. The potentiating interaction between aconitine and higenamine was reversed by pretreating with cholera toxin (CTX) and forskolin. In CTX (100 iim, lh)- and forskolin (30 and 100nM)-treated atria, higenamine significantly depressed the aconitine-induced response, which was abolished by pertussis toxin (PTX, 150/