The effects of salt-induced hypertension on α1- adrenoreceptor expression and cardiovascular physiology in the rainbow trout (Oncorhynchus mykiss)

Xi Chen, Thomas W. Moon, Kenneth R. Olson, Ryan A. Dombkowski, Steve F. Perry

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Experiments were conducted on rainbow trout to determine the impact of dietary salt on arterial blood pressure. After 4-6 wk, fish fed a salt-enriched diet exhibited a 37% elevation of dorsal aortic pressure (from 23.8 ± 1.2 to 32.6 ± 1.4 mmHg) and an 18% increase in ventral aortic pressure (from 33.0 ± 1.5 to 38.9 ± 1.3 mmHg). The hypertension presumably reflected the increase in cardiac output (from 31.0 ± 0.8 to 36.4 ± 2.2 ml·min-1·kg-1) because systemic and branchial resistances were statistically unaltered by salt feeding. The chronic hypertension was associated with a decrease in the pressor responses of the systemic vasculature to catecholamines and hypercapnia in the salt-fed fish. The reduction in α-adrenergic responsiveness of the systemic vasculature is consistent with desensitization or loss of functional α-adrenoceptors (α-ARs). In support of this idea, the salt-fed fish exhibited significantly decreased levels of α1D-AR mRNA in the dorsal aorta and the afferent (ABA) and efferent branchial arteries (EBA). In contrast, however, the results obtained from norepinephrine dose-response curves for EBA and ABA vascular rings in vitro did not provide evidence for loss of function of branchial artery α1-ARs in the salt-fed fish. Indeed, the EC50 for the EBA norepinephrine dose-response curve was significantly reduced (from 3.75 × 10-7 to 2.12 × 10-7 M) in the salt-fed fish, indicating an increase in the binding affinity of the α1-ARs.

Original languageEnglish (US)
Pages (from-to)R1384-R1392
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume293
Issue number3
DOIs
StatePublished - Sep 1 2007

Keywords

  • Afferent branchial artery
  • Blood pressure
  • Efferent branchial artery
  • Epinephrine
  • Hypercapnia
  • Norepinephrine
  • Salt feeding
  • Systemic resistance

ASJC Scopus subject areas

  • Physiology

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