Evidence for multiple adrenoceptor sites in rainbow trout vasculature

H. Y. Xu, K. R. Olson

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

The importance of neuronal and lumenal vascular adrenoceptors in the regulation of vascular reactivity was examined in rainbow trout (Oncorhynchus mykiss), in vivo and in vitro. In vivo, ganglionic blockade with hexamethonium or α-adrenoceptor blockade, with either phentolamine or prazosin, produced similar (7 mmHg) decreases in dorsal aortic blood pressure. The drop in dorsal aortic pressure produced by phentolamine or prazosin was due to reduced systemic vascular resistance. Neither the α-adrenoceptor antagonist, phenoxybenzamine nor chemical sympathectomy with 6-hydroxy-dopamine affected dorsal aortic pressure. However, after chemical sympathectomy, phenoxybenzamine lowered dorsal aortic pressure to levels similar to that produced by either phentolamine or prazosin. Plasma epinephrine and norepinephrine concentrations increased four- and twofold, respectively, in sympathectomized fish. Sympathectomy also produced a leftward shift in the epinephrine dose/response curve of the in vitro perfused splanchnic vasculature, placing the effective catecholamine concentration well within the in vivo plasma levels. These results indicate that following chemical sympathectomy arterial blood pressure is stabilized by circulating catecholamines through the combined effect of increased plasma catecholamine concentrations and increased sensitivity of vascular adrenoceptors. Phenoxybenzamine is incapable of blocking neuronal vascular adrenoceptors but is a potent antagonist of the up-regulated adrenoceptors, suggesting that the latter are localized on the lumenal side of the vessel.

Original languageEnglish (US)
Pages (from-to)470-476
Number of pages7
JournalJournal of Comparative Physiology B
Volume163
Issue number6
DOIs
StatePublished - Dec 1 1993

Keywords

  • Blood pressure
  • Catecholamines
  • Receptors
  • Sympathetic nervous system
  • Trout, Oncorhynchus mykiss

ASJC Scopus subject areas

  • Physiology (medical)
  • Environmental Science(all)
  • Physiology
  • Animal Science and Zoology

Fingerprint Dive into the research topics of 'Evidence for multiple adrenoceptor sites in rainbow trout vasculature'. Together they form a unique fingerprint.

  • Cite this