Decreased sensitivity of vascular smooth muscle from pregnant rats to phenylephrine may be due to increased Nitric Oxide Synthase activity

S. A. Klarr, J. M. Richey, R Clinton Webb, C. J M Van De Ven

Research output: Contribution to journalArticle

Abstract

Vascular smooth muscle (VSM) from pregnant rats is less sensitive to vasoconstriction by phenylephrine than VSM from nonpregnant rats. We and others have demonstrated this in aortic strips, although the mechanism through which this occurs is unknown. We investigated whether such a decreased response to phenylephrine could be seen in the isolated mesenteric vasculature and whether the response could be potentiated by nitric oxide synthase (NOS) inhibition, since it has been suggested that blood vessels from pregnant rats exhibit increased sensitivity to NO. The mesenteric vasculature was perfused with physiological saline solution to establish baseline perfusion pressure, followed by a constant infusion of phenylephrine (3×10-5 M). The NOS inhibitor Nω-Nitro-L-arginine (LNNA) was then infused at 3×10-3 M. As in aorta, phenylephrine produced less vasoconstriction in the mesenteric beds from pregnant rats, perfusion pressure increased 7 mmHg in mesenteric beds from pregnant rats and 32 mmHg in mesenteric beds from nonpregnant rats, (n=3). Addition of LNNA caused a smaller increase in perfusion pressure in mesenteric beds from pregnant rats than nonpregnant rats, 15 vs. 48 mmHg (n=2). These data provide indirect evidence that reduced vasoconstrictor sensitivity in the mesenteric bed of pregnant rats is associated with a greater inhibitory effect of nitric oxide.

Original languageEnglish (US)
JournalFASEB Journal
Volume10
Issue number3
StatePublished - Dec 1 1996
Externally publishedYes

Fingerprint

phenylephrine
Phenylephrine
nitric oxide synthase
Vascular Smooth Muscle
blood vessels
Nitric Oxide Synthase
smooth muscle
Muscle
Rats
rats
vasoconstriction
Perfusion
Vasoconstriction
Pressure
vasoconstrictor agents
Blood vessels
Vasoconstrictor Agents
aorta
Sodium Chloride
sodium chloride

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

Decreased sensitivity of vascular smooth muscle from pregnant rats to phenylephrine may be due to increased Nitric Oxide Synthase activity. / Klarr, S. A.; Richey, J. M.; Webb, R Clinton; Van De Ven, C. J M.

In: FASEB Journal, Vol. 10, No. 3, 01.12.1996.

Research output: Contribution to journalArticle

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