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“Effect of antihistaminic and antiserotonin drugs on vascular responses to E. coli endotoxin in the cat.”.
Proc.Soc.Exper.Biol.& Med.. 1959;100:346.
The vascular response to endotoxin in the cat resembles that seen in anaphylactic shock. It is possible that histamine and 5-HT are released. A study was therefore made of the protection offered by LSD (5 mg/kg i.v.) and an antihistamine, pyrilamine (5 mg/kg i.v.), given alone or together, against the depressor effect and initial increase in pulmonary arterial pressure elicited by 0.05 mg/kg E. coli endotoxin i.v. in the cat under barbiturate anesthesia. Dibenamine was also included in the study as other investigators found dibenzyline (a sympatholytic) protected against endotoxin shock. . The initial increase in pulmonary arterial pressure was diminished, but not significantly, by all the drugs, LSD plus pyrilamine being the most effective. The depressor effect was significantly inhibited by dibenamine alone, LSD alone and LSD plus pyrilamine. Pyrilamine alone did not have a significant effect. All the drugs were ineffective in protecting against the effects of 5 mg/kg endotoxin. It is probable that histamine and 5- HT play a role in endotoxin shock, at least in the initial stages. . Neither LSD alone nor LSD plus pyrilamine gave significant protection in groups of 4 cats. However, when data for these two groups were pooled, the degree of protection against the acute hypotensive effects of endotoxin became statistically significant at the 0.02 level. The author considers that partial protection could be shown for LSD or pyrilamine alone in a larger number of cats. . In preliminary studies it was found that various antihistamines did not uniformly and completely inhibit the vascular responses to histamine, and that dibenzyline and LSD incompletely and unpredictably blocked the BP responses to 5-HT. . Comment: The vascular responses to 5-HT are not so readily inhibited by LSD as those on the isolated uterus.
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