Cardiovascular effects of alpha-adrenergic agents in the dorsal raphe nucleus of the rat.
Local injection of norepinephrine (NE) or phenylephrine into the lateral aspect of the dorsal raphe nucleus results in an increase in blood pressure and heart rate in the urethane-anesthetized rat. The increases in blood pressure and heart rate are blocked by prior injection of phentolamine into the dorsal raphe nucleus and are significantly reduced by i.v. mecamylamine. Selective lesion of serotonergic neurons in the dorsal raphe nucleus by 5,7-dihydroxytryptamine significantly reduces the pressor response to phenylephrine, but does not affect the increase in heart rate in response to phenylephrine. These data are consistent with a central alpha-adrenergic mechanism in the dorsal raphe that elevates blood pressure at least partly by an action on serotonergic neurons and elevates heart rate by a mechanism involving non-serotonergic neurons in the dorsal raphe area.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem / Q000502:physiology*; D002319:Cardiovascular System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007267:Injections; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D009638:Norepinephrine / Q000008:administration & dosage* / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000008:administration & dosage* / Q000494:pharmacology; D011903:Raphe Nuclei / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D010656:Phenylephrine; D008464:Mecamylamine; D009638:Norepinephrine; D010646:Phentolamine