title: Transient receptor potential vanilloid type 4-deficient mice exhibit impaired endothelium-dependent relaxation induced by acetylcholine in vitro and in vivo.
abstract: Agonist-induced Ca2+ entry is important for the synthesis and release of vasoactive factors in endothelial cells. The transient receptor potential vanilloid type 4 (TRPV4) channel, a Ca2+-permeant cation channel, is expressed in endothelial cells and involved in the regulation of vascular tone. Here we investigated the role of TRPV4 channels in acetylcholine-induced vasodilation in vitro and in vivo using the TRPV4 knockout mouse model. The expression of TRPV4 mRNA and protein was detected in both conduit and resistance arteries from wild-type mice. In small mesenteric arteries from wild-type mice, the TRPV4 activator 4alpha-phorbol-12,13-didecanoate increased endothelial [Ca2+]i in situ, which was reversed by the TRPV4 blocker ruthenium red. In wild-type animals, acetylcholine dilated small mesenteric arteries that involved both NO and endothelium-derived hyperpolarizing factors. In TRPV4-deficient mice, the NO component of the relaxation was attenuated and the endothelium-derived hyperpolarizing factor component was largely eliminated. Compared with their wild-type littermates, TRPV4-deficient mice demonstrated a blunted endothelial Ca2+ response to acetylcholine in mesenteric arteries and reduced NO release in carotid arteries. Acetylcholine (5 mg/kg, IV) decreased blood pressure by 37.0+/-6.2 mm Hg in wild-type animals but only 16.6+/-2.7 mm Hg in knockout mice. We conclude that acetylcholine-induced endothelium-dependent vasodilation is reduced both in vitro and in vivo in TRPV4 knockout mice. These findings may provide novel insight into mechanisms of Ca2+ entry evoked by chemical agonists in endothelial cells.
authors.affiliation: Department of Medicine, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA. xfzhang@mcw.edu
authors.forename: David X
authors.initials: DX
authors.lastname: Zhang
authors.forename: Suelhem A
authors.initials: SA
authors.lastname: Mendoza
authors.forename: Aaron H
authors.initials: AH
authors.lastname: Bubolz
authors.forename: Atsuko
authors.initials: A
authors.lastname: Mizuno
authors.forename: Zhi-Dong
authors.initials: ZD
authors.lastname: Ge
authors.forename: Rongshan
authors.initials: R
authors.lastname: Li
authors.forename: David C
authors.initials: DC
authors.lastname: Warltier
authors.forename: Makoto
authors.initials: M
authors.lastname: Suzuki
authors.forename: David D
authors.initials: DD
authors.lastname: Gutterman
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D020013:Calcium Signaling / Q000187:drug effects; D002339:Carotid Arteries / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006973:Hypertension / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D050916:TRPV Cation Channels; C486576:Trpv4 protein, mouse; D014665:Vasodilator Agents; D009569:Nitric Oxide; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester