Pharmacological actions of aconitine alkaloids.

Abstract

Aconitine (AC), mesaconitine (MA), hypaconitine (HA) (50 μg/kg i.v.), benzoylaconine (BA), benzoylmesaconine (BM) and benzoylhypaconine (BH) (5 mg/kg i.v.) produced a weak temporary hypotension in rats which was blocked to some extent by atropine. In the isolated guinea pig right atria, MA and HA (3×10-8 g/ml) mediated a positive inotropic action and a positive chronotropic action. At the higher concentration of 10-7 g/ml, AC, MA and HA exhibited the above actions followed by inhibition of contractions and disorder of the beating rate. In the isolated guinea pig ileum, AC, MA and HA (>10-6 g/ml) caused a contraction which was completely blocked by atropine. In the isolated guinea pig vas deferens, AC, MA and HA (>10-5 g/ml) elicited a contraction which was completely obliterated by phentolamine. In the isolated guinea pig hypogastric nerve-vas deferens, the isolated rabbit mesenteric nerve-jejunum and the isolated rat phrenic nerve-diaphragm, responses induced by the electrical stimulation of the corresponding nerves were inhibited by AC, MA and HA (10-6-10-5 g/ml). Some of the mechanisms of the above actions induced by these alkaloids are discussed. These alkaloids more or less potentiated the hexobarbital anesthesia, inhibited the revolution of the wheel cage, and reduced the rectal temperature in mice, indicating that they have a depressant activity on the central nervous system.