N(ω)-nitro-L-arginine and pulmonary vascular pressure-flow relationship in conscious dogs

K. Nishiwaki, D. P. Nyhan, P. Rock, P. M. Desai, W. P. Peterson, C. G. Pribble, P. A. Murray

Research output: Contribution to journalArticlepeer-review

Abstract

We investigated the effects of an inhibitor of nitric oxide (NO) synthesis, N(ω)-nitro-L-arginine (L-NNA), on the pulmonary vascular pressure-flow relationship in chronically instrumented conscious dogs. The L- arginine analogue L-NNA (20 mg/min for 60 min iv) had no effect on the baseline pressure-flow relationship. This result indicates that tonic release of endothelium-derived relaxing factor (EDRF), which is thought to be NO or a labile NO-generating molecule, is not responsible for low resting pulmonary vasomotor tone in conscious dogs. In contrast, L-NNA caused a leftward shift in the dose-response relationship to the thromboxane mimetic U-46619, indicating that the endogenous release of EDRF modulates the pulmonary vascular response to this vasoconstrictor. Finally, after preconstriction with U-46619, L-NNA abolished the pulmonary vasodilator response to bradykinin (1-10 μg·kg-1·min-1) but had no effect on the pulmonary vasodilator response to sodium nitroprusside (1-10 μg·kg-1·min-1). Thus EDRF does not appear to tonically regulate the baseline pulmonary vascular pressure-flow relationship in conscious dogs. However, EDRF does act to attenuate the magnitude of U-46619-induced pulmonary vasoconstriction. Moreover, the pulmonary vasodilator response to bradykinin is entirely mediated by EDRF in conscious dogs.

Original languageEnglish (US)
Pages (from-to)H1331-H1337
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume262
Issue number5 31-5
StatePublished - 1992

Keywords

  • L-arginine analogue
  • U-46619
  • bradykinin
  • chronic instrumentation
  • endothelium-derived relaxing factor
  • endothelium-derived relaxing factor inhibitor
  • nitric oxide
  • pulmonary circulation
  • sodium nitroprusside

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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