Background: The pathophysiological roles of cystic fibrosis transmembrane-conductance regulator (CFTR) Cl- channels in the regulation of blood pressure (BP) remain controversial. Here we studied the function of CFTR Cl- channels in regulation of BP and in the high-fructose-salt-diet (HFSD) induced hypertension in mice. Methods: The systolic, diastolic and mean BP (SBP, DBP and MBP, respectively) were continuously monitored from unrestricted conscious wild-type (cf tr(+/+)) FVB and CFTR-knockout (cftr(-/-)) mice (8-week old, male). HFSD (64.7% fructose, 2% NaCl water) or control normal starch diet (CNSD, 58.9% corn starch, 0 NaCl water) was given for 8 weeks and vascular Doppler were performed. Real-time PCR and Western blot were used to examine mRNA and protein expression, respectively. Results: The aortic stiffness, daytime and nighttime SBP, DBP, and MBP of the cftr(-/-) mice were significantly higher than those in the age- and gender-matched cftr(+ /+) mice, which is consistent with the findings of increased vascular resistance in cystic fibrosis patients. The aortic stiffness, daytime and nighttime SBP, DBP, and MBP of cftr(+/+) mice fed with HFSD were all significantly higher than those fed with CNSD. Importantly, HFSD caused a significant decrease in mRNA and protein expression of WINK1, WINK4 and CFTR in aorta and mesenteric arteries, but not in the kidney, corroborating that HSFD-induced downregulation of WINKs and loss of CFTR function specifically in the arteries may mediate the increased BP. Conclusions: CFTR regulates peripheral arterial resistance and BP in vivo. HFSD-induced CFTR downregulation specifically in the arteries may be a novel mechanism for hypertension. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of European Cystic Fibrosis Society.