TY - JOUR
T1 - eNOS function is developmentally regulated
T2 - Uncoupling of eNOS occurs postnatally
AU - Mata-Greenwood, Eugenia
AU - Jenkins, Chrystal
AU - Farrow, Kathryn N.
AU - Konduri, G. Ganesh
AU - Russell, James A.
AU - Lakshminrusimha, Satyan
AU - Black, Stephen M.
AU - Steinhorn, Robin H.
PY - 2006/2
Y1 - 2006/2
N2 - 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.
AB - 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.
KW - Development
KW - Endothelial nitric oxide synthase
KW - Nitric oxide
KW - Pulmonary artery
KW - Superoxide
UR - http://www.scopus.com/inward/record.url?scp=33644846537&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33644846537&partnerID=8YFLogxK
U2 - 10.1152/ajplung.00393.2004
DO - 10.1152/ajplung.00393.2004
M3 - Article
C2 - 16143585
AN - SCOPUS:33644846537
SN - 1040-0605
VL - 290
SP - L232-L241
JO - American Journal of Physiology - Lung Cellular and Molecular Physiology
JF - American Journal of Physiology - Lung Cellular and Molecular Physiology
IS - 2
ER -