Tetrahydrobiopterin-dependent preservation of nitric oxide–mediated endothelial function in diabetes by targeted transgenic GTP–cyclohydrolase I overexpression

Endothelial nitric oxide synthase dysfunction in diabetic mice: importance of tetrahydrobiopterin in eNOS dimerisation

“…We have previously shown that STZ-induced diabetes in C57BL/6 mice results in endothelial dysfunction [22]. To ensure that our findings were not specific to the C57BL/6 strain, we carried out similar experiments in Balb/c mice.…”

“…Animals and induction of diabetes by streptozotocin injection The mice used in this study were 12-to 14-weekold males and included the strains Balb/c (Harlan SpragueDawley, Bicester, UK), C57BL/6 (Harlan SpragueDawley) and GCH-Tg (specific overexpression of GTPCH in a C57BL/6 background, as previously described) as well as their wild-type littermates [22]. The experiments were conducted in accordance with the UK Home Office Animals (Scientific Procedures) Act of 1986.…”

“…To ensure that our findings were not specific to the C57BL/6 strain, we carried out similar experiments in Balb/c mice. Diabetes was induced by peritoneal injection of STZ (Sigma-Aldrich, Gillingham, UK), 200 mg/kg for Balb/c and 160 mg/kg for C57BL/6 and GCH-Tg, or of STZ vehicle (citrate buffer; control), as previously described [22][23][24]. Blood glucose was monitored weekly using a one-touch blood glucose meter (Lifescan, High Wycombe, UK); body weight was also measured weekly.…”

“…Isometric tension vasomotor studies Aortic vasomotor function was studied using organ bath chambers (MultiMyograph 610M; Danish Myo Technology, Aarhus, Denmark), as previously described [22]. Briefly, two rings, each 2 mm in length, were divided from each thoracic aorta.…”

“…We also investigated the role of BH4 in eNOS dimerisation in diabetes using the GTPCH transgenic (GCH-Tg) mouse, in which BH4 biosynthesis is specifically augmented in the vascular endothelium [22].…”