title: Direct effects of Rho-kinase inhibitor on pial microvessels in rabbits.
abstract: OBJECTIVE
  Rho-kinase inhibitor is widely used for prevention of cerebral vascular spasm. However, the cerebral pial vascular action of Rho-kinase inhibitor has not been investigated. We therefore evaluated the direct effects of Y-27632, a Rho-kinase inhibitor, on pial microvessels.
  
  
  METHODS
  Experiments were performed on anesthetized rabbits. A closed cranial window was used to visualize the pial microcirculation. After baseline hemodynamic and pial vascular measurements, the cranial window was superfused with four increasing concentrations of Y-27632 (10(-9), 10(-7), 10(-6), 10(-5) mol l(-1); n = 7) dissolved in artificial cerebrospinal fluid for 7 min each. We measured the diameters of pial vessels, mean arterial pressure (MAP), heart rate (HR), and rectal temperature at 7 min after application of each Y-27632 concentration.
  
  
  RESULTS
  MAP, HR, rectal temperature, arterial pH, PaCO2, PaO2, and plasma Na(+), K(+) and glucose concentrations did not change significantly during the experimental period. Y-27632 at 10(-9) to 10(-7) mol l(-1) did not produce any significant change in pial arterioles. Topical application of Y-27632 at 10(-6) and 10(-5) mol l(-1) produced pial large (8.4 ± 5.7 and 19.8 ± 12.7 %) and small (10.1 ± 8.5 and 18.1 ± 12.3 %) arterioles dilation. However, Y-27632 did not produce any change in pial large and small venules.
  
  
  CONCLUSIONS
  We evaluated the direct effects of Y-27632 on pial microvessels. Y-27632 dilates only pial arterioles in a concentration-dependent manner, and most at a concentration of 10(-5) mol l(-1). Y-27632 is a potent cerebral pial arteriolar dilator but is not a venular dilator.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi, 409-3898, Japan, mkotodaanes@yahoo.co.jp.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kotoda
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Ishiyama
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Shintani
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsukawa
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects; D001160:Arterioles / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D002196:Capillaries / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D008833:Microcirculation / Q000187:drug effects; D010841:Pia Mater / Q000098:blood supply* / Q000187:drug effects*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D011817:Rabbits; D014664:Vasodilation / Q000187:drug effects; D014699:Venules / Q000187:drug effects; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000577:Amides; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C108830:Y 27632; D054460:rho-Associated Kinases