Increasing resting vascular tone in conscious dogs does not alter the mesenteric vasoconstrictor responses to ANP

Robyn L. Woods, Simon M. Fitzpatrick

Research output: Contribution to journalArticleResearchpeer-review


1. There is considerable in vitro evidence that, at high concentrations, atrial natriuretic peptide (ANP) acts directly on pre-constricted blood vessels to cause vasorelaxation. Previously, we have seen vasoconstriction rather than vasodilatation in conscious dogs at physiological levels of the peptide. It is possible that the low resting vascular tone in our conscious, unstressed animals prevented the manifestation of the relaxant properties of ANP in vivo. 2. In the present study in conscious, instrumented dogs, we studied the mesenteric vascular responses to 10 min infusions of ANP (10, 25, 50 and 100 ng/kg per min, i.v.) when resting vascular tone was enhanced with a continuous infusion of AVP (75 pg/kg per min, i.v.) and compared these with responses in the normal condition (no added AVP). 3. Mesenteric vascular resistance was increased by ANP (10, 25, 50 and 100 ng/kg per min) by 9 ± 2, 20 ± 6, 29 ± 7 and 32 ± 9%, respectively. Increased resting vascular tone did not alter the mesenteric vasoconstrictor response to ANP. Thus, the discrepancy between in vitro (vasorelaxation) and in vivo (vasoconstriction) findings may be the result of the widely different concentrations of ANP used, rather than the state of resting vascular tone.

Original languageEnglish
Pages (from-to)95-97
Number of pages3
JournalClinical and Experimental Pharmacology and Physiology
Issue number1
Publication statusPublished - 1996
Externally publishedYes


  • Arginine vasopressin
  • Atrial natriuretic factor
  • Atrial natriuretic peptide
  • Blood pressure
  • Mesenteric blood flow
  • Mesenteric vascular resistance
  • Vasopressin

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