title: Vasomotor response induced by change of extracellular potassium and magnesium in cerebral penetrating arterioles.
abstract: We investigated the effects of changing the extracellular potassium as well as magnesium concentration ([K+]₀ and [Mg²+]₀) in cerebral penetrating arterioles. The internal diameter of isolated pressurized cerebral penetrating arterioles in rat was measured under the microscope in the low [K+]₀, low [Mg²+]₀ and high [Mg²+]₀, respectively. Vascular responses induced by the low [K+]₀ were observed in the absence and presence of several inhibitors. The low [K+]₀ produced a biphasic response consisting of an initial transient constriction followed by dilation. The transient constriction was attenuated by Na+-K+-adenosine triphosphatase (ATPase) inhibitor in a concentration-dependent manner and L-type Ca²+ channel inhibitor but not by all K+ channel inhibitors. The low [Mg²+]₀ significantly induced constriction, whereas the high [Mg²+]₀ induced dilation. We analyzed that transient constriction in the low [K+]₀ may be led by membrane depolarization induced by inactivity in Na+-K+-ATPase. The vasomotor responses of the changing of [K+]₀ as well as [Mg²+]₀ in a cerebral microcirculation may influence the pathological and therapeutic condition in cerebrovascular diseases, and may provide new therapeutic targets.
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Murata
authors.forename: Tetsuyoshi
authors.initials: T
authors.lastname: Horiuchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Goto
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Li
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hongo
mesh_terms: D000818:Animals; D001160:Arterioles / Q000378:metabolism* / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002536:Cerebral Arteries / Q000378:metabolism* / Q000502:physiology; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism* / Q000502:physiology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014666:Vasomotor System / Q000187:drug effects / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D008274:Magnesium; D011188:Potassium