Exogenous norepinephrine constricts cerebral arterioles via α2-adrenoceptors in newborn pigs

D. W. Busija, Charles Leffler

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The purpose of this study was to determine whether exogenous norepinephrine mediates cerebrovascular constriction via α1- or α2-adrenoceptors in anesthetized neonatal pigs. Diameters of pial arterioles in anesthetized piglets, 1-6 days old, were investigated using a 'closed' cranial window. We examined constrictor effects of norepinephrine on pial arterioles in the absence and presence of relatively selective α1- (prazosin) and α2- (yohimbine) adrenoceptor antagonists (1 mg/kg i.v.). Yohimbine and prazosin inhibited pial arteriolar constriction induced by topical application of clonidine and phenylephrine (10-6 and 10-4 M, respectively), and yohimbine did not affect the response to topical phenylephrine. In one group diameter was 188 ± 13 (mean ± SEM) μm during control and 146 ± 12 μm during 10-5 M norepinephrine (22 ± 5% constriction). Following yohimbine the same vessels did not constrict significantly. In another group 10-5 M norepinephrine constricted arterioles by 22 ± 5%, and this response was unaffected by prazosin (24 ± 5% constriction). We conclude that pial arterioles are responsive to both α1- and α2-adrenoceptor agonists, that intravenous administration of prazosin and yohimbine results in these drugs crossing the blood-brain barrier and inhibiting constrictor effects of agonists, and that norepinephrine constricts pial arterioles predominantly via α2-adrenoceptors.

Original languageEnglish (US)
Pages (from-to)184-188
Number of pages5
JournalJournal of Cerebral Blood Flow and Metabolism
Volume7
Issue number2
DOIs
StatePublished - Jan 1 1987

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Yohimbine
Arterioles
Adrenergic Receptors
Prazosin
Norepinephrine
Swine
Constriction
Phenylephrine
Clonidine
Blood-Brain Barrier
Intravenous Administration
Pharmaceutical Preparations

All Science Journal Classification (ASJC) codes

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine

Cite this

Exogenous norepinephrine constricts cerebral arterioles via α2-adrenoceptors in newborn pigs. / Busija, D. W.; Leffler, Charles.

In: Journal of Cerebral Blood Flow and Metabolism, Vol. 7, No. 2, 01.01.1987, p. 184-188.

Research output: Contribution to journalArticle

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