Abstract

Veratramine (200-600 microgm./kgm.) lowers the blood pressure, decreases the heart rate, produces muscular rigidity and clonic convulsions in the pentobarbitalized rat. It produces some antagonism of the heart rate increase caused by epinephrine and N-isopropylarterenol.

As little as 160 microgm. of veratramine pet kgm. produce some muscular rigidity, and myoclonic jerks, decreased heart rate, and lowered blood pressure in the anesthetized dog. As the dose is increased to 1 mgm. per kgm. the effects gradually become mote pronounced with clonic convulsions, increased respiration, low blood pressure and very slow heart rate. The effects are not altered by atropine. The cardiac acceleration produced by 2-3 microgm. of epinephrine per kgm. can be antagonized as much as 70 per cent although the antagonism of larger amounts of epinephrine and of similar amounts of N-isopropylarterenol is less. The antiacceleratory action is more pronounced in unanesthetized and thiopental-depressed dogs, is less with pentobarbital anesthesia, and is least with ether or sodium barbital.

In a single experiment, 250 microgm. of veratramine pet kgm., taken orally, were not well tolerated in man.