Coompo Research Chemicals

Lycorenine (10--40 mg/kg p.o.) produced a decrease in blood pressure in conscious rats which was greater in hypertensive rats than in normotensive rats. In conscious dogs, lycorenine (5 or 10 mg/kg i.v.) produced rises in blood pressure and heart rate except for a few instances, while it produced a decrease in blood pressure in pentobarbital anesthetized dogs. Thus, there are species differences in cardiovascular effects of lycorenine between conscious rats and dogs. The development of tachyphylaxis to the vasodepressor actions of lycorenine and its related compounds was related to their alpha-adrenergic blocking activities at the time of the second injection in anesthetized rats. Desipramine which abolished or diminished the development of tachyphylaxis to the vasodepressor action of lycorenine (5 or 7.5 mg/kg i.v.), shortened the duration of its vasodepressor action and reduced its alpha-adrenergic blocking action. These results indicate that the development of tachyphylaxis to the vasodepressor action of lycorenine is ascribed to maintenance of its alpha-adrenergic blocking action.

Lycorenine may produce a decrease in blood pressure as the result of alpha-adrenergic blockade in conjunction with the reduction of the spontaneous sympathetic nerve activity, and produce bradycardia by modifying vagal activity.