A key role for tetrahydrobiopterin‐dependent endothelial NOS regulation in resistance arteries: studies in endothelial cell tetrahydrobiopterin‐deficient mice. (13th March 2017)

• Record Type: Journal Article
• Authors: Chuaiphichai, Surawee; Crabtree, Mark J; Mcneill, Eileen; Hale, Ashley B; Trelfa, Lucy; Channon, Keith M; Douglas, Gillian
• Is Part Of: British journal of pharmacology. Volume 174:Number 8(2017)
• Page Start: 657
• Page End: 671
• Publication Date: 2017-03-13
• Subjects: Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/bph.13728
• Languages: English
• ISSNs: 0007-1188

Abstract

Abstract : Background and Purpose: The cofactor tetrahydrobiopterin (BH4) is a critical regulator of endothelial NOS (eNOS) function, eNOS‐derived NO and ROS signalling in vascular physiology. To determine the physiological requirement for de novo endothelial cell BH4 synthesis for the vasomotor function of resistance arteries, we have generated a mouse model with endothelial cell‐specific deletion of Gch1, encoding GTP cyclohydrolase 1 (GTPCH), an essential enzyme for BH4 biosynthesis, and evaluated BH4‐dependent eNOS regulation, eNOS‐derived NO and ROS generation. Experimental Approach: The reactivity of mouse second‐order mesenteric arteries was assessed by wire myography. High performance liquid chromatography was used to determine BH4, BH2 and biopterin. Western blotting was used for expression analysis. Key Results: Gch1 fl/fl Tie2cre mice demonstrated reduced GTPCH protein and BH4 levels in mesenteric arteries. Deficiency in endothelial cell BH4 leads to eNOS uncoupling, increased ROS production and loss of NO generation in mesenteric arteries of Gch1 fl/fl Tie2cre mice. Gch1 fl/fl Tie2cre mesenteric arteries had enhanced vasoconstriction to U46619 and phenylephrine, which was abolished by L‐NAME. Endothelium‐dependent vasodilatations to ACh and SLIGRL were impaired in mesenteric arteries from Gch1 fl/fl Tie2cre mice, compared with those from wild‐type littermates. Loss of eNOS‐derived NO‐mediated vasodilatation was associated with increased eNOS‐derived H2 O2 and cyclooxygenase‐derived vasodilator in Gch1 fl/fl Tie2cre mesenteric arteries. Conclusions and Implications: Endothelial cell Gch1 and BH4‐dependent eNOS regulation play pivotal roles in maintaining vascular homeostasis in resistance arteries. Therefore, targeting vascular Gch1 and BH4 biosynthesis may provide a novel therapeutic target for the prevention and treatment of microvascular dysfunction in patients with cardiovascular disease.