Faculty Collaboration Database

eNOS function is developmentally regulated: uncoupling of eNOS occurs postnatally. Am J Physiol Lung Cell Mol Physiol 2006 Feb;290(2):L232-41

Date

09/07/2005

Pubmed ID

16143585

Pubmed Central ID

PMC2077088

DOI

10.1152/ajplung.00393.2004

Scopus ID

2-s2.0-33644846537 (requires institutional sign-in at Scopus site)   60 Citations

Abstract

At birth, the transition to gas breathing requires the function of endothelial vasoactive agents. We investigated the function of endothelial nitric oxide synthase (eNOS) in pulmonary artery (PA) vessels and endothelial cells isolated from fetal and young (4-wk) sheep. We found greater relaxations to the NOS activator A-23187 in 4-wk-old compared with fetal vessels and that the NOS inhibitor nitro-L-arginine blocked relaxations in both groups. Relaxations in 4-wk vessels were not blocked by an inhibitor of soluble guanylate cyclase, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one, but were partially blocked by catalase. We therefore hypothesized that activation of eNOS produced reactive oxygen species in 4-wk but not fetal PA. To address this question, we studied NO and superoxide production by endothelial cells at baseline and following NOS stimulation with A-23187, VEGF, and laminar shear stress. Stimulation of NOS induced phosphorylation at serine 1177, and this event correlated with an increase in NO production in both ages. Upon stimulation of eNOS, fetal PA endothelial cells (PAEC) produced only NO. In contrast 4-wk-old PAEC produced superoxide in addition to NO. Superoxide production was blocked by L-NAME but not by apocynin (an NADPH oxidase inhibitor). L-Arginine increased NO production in both cell types but did not block superoxide production. Heat shock protein 90/eNOS association increased upon stimulation and did not change with developmental age. Cellular levels of total and reduced biopterin were higher in fetal vs. 4-wk cells. Sepiapterin [a tetrahydrobiopterin (BH4) precursor] increased basal and stimulated NO levels and completely blocked superoxide production. We conclude that the normal function of eNOS becomes uncoupled after birth, leading to a developmental adaptation of the pulmonary vascular system to produce oxygen species other than NO. We speculate this may be related to cellular production and/or maintenance of BH4 levels.

Author List

Mata-Greenwood E, Jenkins C, Farrow KN, Konduri GG, Russell JA, Lakshminrusimha S, Black SM, Steinhorn RH

Author

Girija Ganesh Konduri MD Chief, Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Aging
Animals
Arginine
Calcimycin
Endothelium, Vascular
Enzyme Activation
Fetus
HSP90 Heat-Shock Proteins
Humans
Nitric Oxide Synthase Type III
Pulmonary Artery
Reactive Oxygen Species
Recombinant Proteins
Sheep
Stress, Mechanical
Superoxides
Vascular Endothelial Growth Factor A
Vasodilation