TY - JOUR
T1 - Increased expression of cyclooxygenase-2 mediates enhanced contraction to endothelin ETA receptor stimulation in endothelial nitric oxide synthase knockout mice
AU - Zhou, Yingbi
AU - Mitra, Srabani
AU - Varadharaj, Saradhadevi
AU - Parinandi, Narasimham
AU - Zweier, Jay L.
AU - Flavahan, Nicholas A.
PY - 2006/6
Y1 - 2006/6
N2 - The aim of this study was to determine whether prolonged loss of NO activity, in endothelial NO synthase knockout (eNOS) mice, influences endothelin (ET) ETA receptor-mediated smooth muscle contraction and, if so, to define the underlying mechanism(s). In isolated endothelium-denuded abdominal aortas, contractions to the selective ETA receptor agonist ET-1(1-31) were significantly increased in aortas from eNOS compared with wild-type (WT) mice. In contrast, contractions to the α1-adrenergic agonist phenylephrine or the thromboxane (TX) A2 analog U-46619 were similar between eNOS and WT mice. Immunofluorescent and Western blot analysis demonstrated that the aortic expression of ETA receptors was decreased in eNOS compared with WT mice. Contractions evoked by ET-1(1-31), but not phenylephrine, were reduced by inhibition of cyclooxygenase-2 (COX-2) (indomethacin or celecoxib) or of TXA2/prostaglandin H2 receptors (SQ-29548). After COX inhibition, contractions to ET-1(1-31) were no longer increased and were actually decreased in eNOS compared with WT aortas. Western blot analysis revealed that endothelium-denuded abdominal aortas express COX-2, but not COX-1, and that expression of COX-2 was significantly increased in eNOS compared with WT mice. Contractions to the COX substrate arachidonic acid were also increased in eNOS aortas. Furthermore, ET-1(1-31) but not phenylephrine stimulated production of the TXA2 metabolite TXB2, which was increased in eNOS compared with WT aortas. Therefore, COX-2 plays a crucial and selective role in ETA-mediated smooth muscle contraction. Furthermore, COX-2 expression is increased in eNOS mice, which overcomes a reduced expression of ETA receptors and enables a selective increase in contraction to ETA receptor stimulation.
AB - The aim of this study was to determine whether prolonged loss of NO activity, in endothelial NO synthase knockout (eNOS) mice, influences endothelin (ET) ETA receptor-mediated smooth muscle contraction and, if so, to define the underlying mechanism(s). In isolated endothelium-denuded abdominal aortas, contractions to the selective ETA receptor agonist ET-1(1-31) were significantly increased in aortas from eNOS compared with wild-type (WT) mice. In contrast, contractions to the α1-adrenergic agonist phenylephrine or the thromboxane (TX) A2 analog U-46619 were similar between eNOS and WT mice. Immunofluorescent and Western blot analysis demonstrated that the aortic expression of ETA receptors was decreased in eNOS compared with WT mice. Contractions evoked by ET-1(1-31), but not phenylephrine, were reduced by inhibition of cyclooxygenase-2 (COX-2) (indomethacin or celecoxib) or of TXA2/prostaglandin H2 receptors (SQ-29548). After COX inhibition, contractions to ET-1(1-31) were no longer increased and were actually decreased in eNOS compared with WT aortas. Western blot analysis revealed that endothelium-denuded abdominal aortas express COX-2, but not COX-1, and that expression of COX-2 was significantly increased in eNOS compared with WT mice. Contractions to the COX substrate arachidonic acid were also increased in eNOS aortas. Furthermore, ET-1(1-31) but not phenylephrine stimulated production of the TXA2 metabolite TXB2, which was increased in eNOS compared with WT aortas. Therefore, COX-2 plays a crucial and selective role in ETA-mediated smooth muscle contraction. Furthermore, COX-2 expression is increased in eNOS mice, which overcomes a reduced expression of ETA receptors and enables a selective increase in contraction to ETA receptor stimulation.
KW - Arachidonic acid
KW - Endothelin-1(1-31)
KW - Prostaglandin H
KW - Thromboxane A
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U2 - 10.1161/01.RES.0000224120.52792.10
DO - 10.1161/01.RES.0000224120.52792.10
M3 - Article
C2 - 16645140
AN - SCOPUS:33745382953
SN - 0009-7330
VL - 98
SP - 1439
EP - 1445
JO - Circulation research
JF - Circulation research
IS - 11
ER -