Effect of lesions of the nucleus tractus solitarii on the cardiovascular actions of clonidine in conscious rats

R. W. Rockhold, Robert William Caldwell

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Clonidine has been postulated to produce cardiovascular effects, the most noticeable of which are hypotension and bradycardia, by interaction with the nucleus tractus solitarii (NTS), a cranial nucleus in the dorsal medulla. The experiments reported herein, examined the effects of clonidine (30 μg/kg, i.v.) prior to and following bilateral electrolytic lesioning of the NTS. The studies were performed in conscious, spontaneously hypertensive (SHR) and Wistar-Kyoto rats (WKY). Clonidine produced marked hypotension and bradycardia in conscious, NTS-intact SHR. Intact WKY exhibited a biphasic response to clonidine with an initial hypertension preceeding a moderate decrease in blood pressure. Heart rate responded similarly to the SHR. Lesioning of the NTS, in both SHR and WKY, induced hypertension. Virtual abolition of the hypotension and bradycardia to clonidine was noted in lesioned SHR upon subsequent administration of clonidine. Nucleus tractus solitarii lesioning in WKY did not significantly alter clonidine-induced hypotension; however, the initial hypertensive phase was abolished following lesioning and bradycardia was blunted. These results indicate that the NTS plays an important role in the mediation of both the hypotension and bradycardia seen with clonidine in SHR. The differing responses of SHR and WKY to clonidine after NTS lesions may also indicate altered functional roles for the NTS in these two strains.

Original languageEnglish (US)
Pages (from-to)347-354
Number of pages8
JournalNeuropharmacology
Volume18
Issue number4
DOIs
StatePublished - Jan 1 1979
Externally publishedYes

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Solitary Nucleus
Clonidine
Inbred WKY Rats
Bradycardia
Hypotension
Controlled Hypotension
Hypertension
Heart Rate
Blood Pressure

Keywords

  • SHR medullary lesions
  • central vasomotor control
  • clonidine
  • nucleus tractus solitarii

ASJC Scopus subject areas

  • Pharmacology
  • Cellular and Molecular Neuroscience

Cite this

Effect of lesions of the nucleus tractus solitarii on the cardiovascular actions of clonidine in conscious rats. / Rockhold, R. W.; Caldwell, Robert William.

In: Neuropharmacology, Vol. 18, No. 4, 01.01.1979, p. 347-354.

Research output: Contribution to journalArticle

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