title: Microtubule depolymerization facilitates contraction of rat aorta via activation of Rho-kinase.
abstract: This study tests the hypothesis that microtubule (MT) depolymerization facilitates contraction of rat aorta via activation of Rho-kinase. Aortic rings from Sprague-Dawley rats were placed in a muscle bath for the measurement of isometric force generation. Bath temperature was decreased from 37 to 10-20 degrees C (30 min), inducing MT depolymerization. Some vessels were treated with nocodazole (10(-5) M) or colchicine (10(-8)-10(-5) M) to stabilize the MTs in the depolymerized state, and the remaining vessels were treated with dimethyl sulfoxide (DMSO: vehicle). Warming of vessels to 37 degrees C induced a significantly greater contraction in nocodazole- and colchicine-treated vessels as compared with controls, and this increase was blocked by pretreatment with taxol (10(-5) M; a MT stabilizing agent) [force (mg): NOC 1159 +/- 93; COL 1138 +/- 69; DMSO 578 +/- 14; TAX + NOC 526 +/- 43; TAX + COL 538 +/- 90]. Following the sustained contraction in response to rewarming, Rho-kinase inhibition with Y-27632 (10(-5) M) relaxed nocodazole- and colchicine-treated rings to a significantly greater extent as compared to DMSO-treated vessels (percent relaxation: NOC 64 +/- 2; COL 65 +/- 5; DMSO 33 +/- 5). These results support the hypothesis that MT depolymerization facilitates contraction of rat aorta via activation of Rho-kinase.
authors.affiliation: Department of Physiology, University of Michigan, Ann Arbor, MI 48019, USA. kanchanc@umich.edu
authors.forename: Kanchan
authors.initials: K
authors.lastname: Chitaley
authors.forename: R Clinton
authors.initials: RC
authors.lastname: Webb
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D003078:Colchicine / Q000494:pharmacology; D004789:Enzyme Activation; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015739:Nocodazole / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D054460:rho-Associated Kinases
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D015739:Nocodazole; D003078:Colchicine