Effects of Guan-Fu Base A on rabbit red cell membrane, rat capillary permeability and guinea pig heart atrium

Guan-Fu base A is a new anti-arrhythmia alkaloid, isolated from the tuber of Aconitum coreanum in this Institute. In hemolysis tests by 0.5% NaCl, 50 degree, pH 5.5 and saponin the rabbit rbc were stabilized by Base A 5, 0.6, 1.2 and 0.12 mM, respectively. Intradermal injections of base A 10 or 20 mg/kg decreased the capillary permeability in rat skin, as seen by th extravasation of Evans blue. In isolated spontaneously beating right heart atrium of guinea pigs base A (0.12 mM) caused a 29% reduction of beating rate and a 23% reduction of the tachycardia rate produced by isoproterenol 0.4 microM, but did not depress the contractile force in 30 min. Iso (0.4 microM) still accelerated the beating and enhanced the force after the beating rate and been reduced by Base A. Hence base A is not an adrenergic beta receptor blockader.