title: ROCK inhibition prevents fetal serum-induced alteration in structure and function of organ-cultured mesenteric artery.
abstract: Chronic treatment with fetal bovine serum (FBS) causes contractility reduction, morphological alteration and DNA synthesis in organ-cultured vascular tissues. Here, we tested the hypothesis that chronic inhibition of ROCK has a protective effect on FBS-induced alterations in small arteries. Rabbit mesenteric arterial rings were cultured in FBS-supplemented culture medium with or without Y-27632, a reversible ROCK inhibitor. Chronic Y-27632 treatment prevented FBS-induced gradual arterial constriction, wall thickening, reduced contractility, and increased ROCK-specific MYPT1 Thr853 phosphorylation. Treatment with Y-27632 also prevented decreased eNOS mRNA expression, and reduced acetylcholine-induced relaxation. Sudden application of Y-27632 to pre-cultured rings reduced MYPT1 phosphorylation and re-widened the constricted rings. Chronic treatment with Y-27632, however, rather augmented than reduced the FBS-induced RhoA over-expression, also increased ROCK1 and MYPT1 expression and averted the FBS-induced reduction of MLC expression, suggesting a compensation of inhibited RhoA/ROCK activity. Sudden removal of Y-27632 caused a rebound in MYPT1 phosphorylation and vasoconstriction in rabbit mesenteric artery. To test which ROCK isoform has greater involvement in FBS-induced contraction, haploinsufficient Rock1+/- and Rock2+/- mouse mesenteric arterial rings were subjected to organ-culture. FBS-induced contraction and RhoA over-expression in either heterozygous animal was not different from wild-type animals. These results suggest that FBS-induced contraction is mediated by up-regulation of RhoA and subsequent activation of ROCK. In conclusion, chronic ROCK inhibition produces some effects that protect against FBS-stimulated vasoconstriction and remodeling. There are also negative effects that a sudden withdrawal of ROCK inhibitor might cause a stronger vasoconstriction than before it was used.
authors.affiliation: Boston Biomedical Research Institute, 64 Grove St, Watertown, MA 02472, USA.
authors.forename: Yang Hoon
authors.initials: YH
authors.lastname: Huh
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.forename: James K
authors.initials: JK
authors.lastname: Liao
authors.forename: Toshio
authors.initials: T
authors.lastname: Kitazawa
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D003251:Constriction, Pathologic / Q000201:enzymology / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008638:Mesenteric Arteries / Q000201:enzymology* / Q000473:pathology; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000473:pathology; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase; D009924:Organ Culture Techniques; D010766:Phosphorylation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology*; D011817:Rabbits; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D011725:Pyridines; C108830:Y 27632; C515854:Rock1 protein, mouse; C515855:Rock2 protein, mouse; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D043263:Myosin-Light-Chain Phosphatase; C510645:Ppp1r12a protein, mouse; C526380:RhoA protein, mouse; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein