Maturational changes in the regulation of pulmonary vascular tone by nitric oxide in neonatal rats

Louis G. Chicoine, Michael L. Paffett, Mark R. Girton, Matthew J. Metropoulus, Mandar S. Joshi, John Anthony Bauer, Leif D. Nelin, Thomas C. Resta, Benjimen R. Walker

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Nitric oxide (NO) is an important regulator of vasomotor tone in the pulmonary circulation. We tested the hypothesis that the role NO plays in regulating vascular tone changes during early postnatal development. Isolated, perfused lungs from 7- and 14-day-old Sprague-Dawley rats were studied. Baseline total pulmonary vascular resistance (PVR) was not different between age groups. The addition of KCl to the perfusate caused a concentration-dependent increase in PVR that did not differ between age groups. However, the nitric oxide synthase (NOS) inhibitor Nω-nitro-L-arginine augmented the K+-induced increase in PVR in both groups, and the effect was greater in lungs from 14-day-old rats vs. 7-day-old rats. Lung levels of total endothelial, inducible, and neuronal NOS proteins were not different between groups; however, the production rate of exhaled NO was greater in lungs from 14-day-old rats compared with those of 7-day-old rats. Vasodilation to 0.1 μM of the NO donor spermine NONOate was greater in 14-day lungs than in 7-day lungs, and lung levels of both soluble guanylyl cyclase and cGMP were greater at 14 days than at 7 days. Vasodilation to 100 μM of the cGMP analog 8-(4-chlorophenylthio) guanosine-3′,5′-cyclic monophosphate was greater in 7-day lungs than in 14-day lungs. Our results demonstrate that the pulmonary vascular bed depends more on NO production to modulate vascular tone at 14 days than at 7 days of age. The observed differences in NO sensitivity may be due to maturational increases in soluble guanylyl cyclase protein levels.

Original languageEnglish
Pages (from-to)L1261-L1270
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Issue number5
StatePublished - Nov 2007


  • Guanosine-3′,5′-cyclic monophosphate
  • Isolated perfused lungs
  • Nitric oxide synthase
  • Pulmonary vascular resistance
  • Soluble guanylyl cyclase

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology


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