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THE DEPRESSOR ACTION OF THE VERATRUM ALKALOIDS

1951; Wiley; Volume: 6; Issue: 4 Linguagem: Inglês

10.1111/j.1476-5381.1951.tb00679.x

2056-8177

G. S. Dawes, J. C. Mott, J. G. Widdicombe,

Chemical synthesis and alkaloids

In two recent papers Stutzman and his colleagues have raised some new points about the mode of action of the veratrum alkaloids upon the cardiovascular system.Using " Veriloid " (" a purified reproducible extract of Veratrum viride prepared by the Riker Laboratories of Los Angeles ") they observed that cutting both cervical vagi eliminated the bradycardia, but did not alter quantitatively the fall of blood pressure when this extract was injected intravenously into dogs (Stutzman, Simon, and Maison, 1951).Yet there is ample evidence that cutting the vagi abolishes or very greatly reduces the fall of blood pressure and heart rate which follows the rapid intravenous injection of a single dose of crude extracts of Veratrum album, or Veratrum viride, or of the pure substances veratridine, protoveratrine, or cevadine.Now, veriloid, according to Stutzman, Maison, and Kusserow (1949), is a mixture of alkaloids from which none of the previously described potent alkaloids of Verattrum viride has been obtained.It therefore seemed possible that veriloid contained alkaloids which acted in a different manner from those previously investi- gated.In the first part of this paper, by applying the methods of investigation previously used on other veratrum alkaloids, we have shown that veriloid possesses qualitatively similar properties.Stutzman, Simon, and Maison (1951) also observed that infusions of germitrine, protoveratrine, germidine, germerine, and veratridine into dogs anaesthetized with pentobarbitone (nembutal) caused a fall of blood pressure which was not altered quantitatively by cutting the vagi.They therefore concluded that under these cir- cumstances the Bezold reflex, the afferent fibres of which run in the vagi, is not responsible for the depressor action.In this respect also their results differed from those of previous workers in this field, who had used rapid single injections to test the reaction of the animal.The question is relevant to clinical practice, since a slow intravenous infusion might be expected to mimic the conditions in the circula- tion after a dose had been taken by mouth.Experience with the use of the veratrum alkaloids for studying the Bezold reflex over a number of years by no means agrees with the conclusions of Stutzman and his colleagues.In the first place it is not suggested that the Bezold reflex is alone responsible for the fall of blood pressure and heart rate on intravenous injection of veratridine in the dog, since in 1943 Krayer, Wood, and Montes showed that there was a central action, which caused a fall of heart rate.Yet the dose required to produce this central action was some- what larger than that required to produce the Bezold reflex on injection into the