title: Rho-kinase inhibition attenuates calcium-induced contraction in β-escin but not Triton X-100 permeabilized rabbit femoral artery.
abstract: K+-depolarization (KCl) of smooth muscle has long been known to cause Ca2+-dependent contraction, but only recently has this G protein-coupled receptor (GPCR)-independent stimulus been associated with rhoA kinase (ROCK)-dependent myosin light chain (MLC) phosphatase inhibition and Ca2+ sensitization. This study examined effects of ROCK inhibition on the concentration-response curves (CRCs) generated in femoral artery by incrementally adding increasing concentrations of KCl to intact tissues, and Ca2+ to tissues permeabilized with Triton X-100, β-escin and α-toxin. For a comparison, tissue responses were assessed also in the presence of protein kinase C (PKC) and MLC kinase inhibition. The ROCK inhibitor H-1152 induced a strong concentration-dependent inhibition of a KCl CRC. A relatively low GF-109203X concentration (1 μM) sufficient to inhibit conventional PKC isotypes also inhibited the KCl CRC but did not affect the maximum tension. ROCK inhibitors had no effect on the Ca2+ CRC induced in Triton X-100 or α-toxin permeabilized tissues, but depressed the maximum contraction induced in β-escin permeabilized tissue. GF-109203X at 1 μM depressed the maximum Ca2+-dependent contraction induced in α-toxin permeabilized tissue and had no effect on the Ca2+ CRC induced in Triton X-100 permeabilized tissue. The MLC kinase inhibitor wortmannin (1 μM) strongly depression the Ca2+ CRCs in tissues permeabilized with Triton X-100, α-toxin and β-escin. H-1152 inhibited contractions induced by a single exposure to a submaximum [Ca2+] (pCa 6) in both rabbit and mouse femoral arteries. These data indicate that β-escin permeabilized muscle preserves GPCR-independent, Ca2+- and ROCK-dependent, Ca2+ sensitization.
authors.affiliation: Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, 1101 East Marshall Street, PO Box 980614, Richmond, VA 23298-0614, USA.
authors.forename: Lyndsay J
authors.initials: LJ
authors.lastname: Clelland
authors.forename: Brendan M
authors.initials: BM
authors.lastname: Browne
authors.forename: Silvina M
authors.initials: SM
authors.lastname: Alvarez
authors.forename: Amy S
authors.initials: AS
authors.lastname: Miner
authors.forename: Paul H
authors.initials: PH
authors.lastname: Ratz
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002317:Cardiovascular Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004928:Escin / Q000494:pharmacology*; D005260:Female; D005263:Femoral Artery / Q000201:enzymology*; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D008301:Maleimides / Q000494:pharmacology*; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D017830:Octoxynol / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010539:Permeability; D011189:Potassium Chloride / Q000378:metabolism / Q000494:pharmacology; D011817:Rabbits; D013501:Surface-Active Agents / Q000494:pharmacology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: C459092:2-methyl-1-((4-methyl-5-isoquinolinyl)sulfonyl)homopiperazine; D002317:Cardiovascular Agents; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D013501:Surface-Active Agents; D011189:Potassium Chloride; D004928:Escin; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D017830:Octoxynol; D054460:rho-Associated Kinases; C070515:bisindolylmaleimide I; D002118:Calcium