title: The effects of topical and intravenous ropivacaine on canine pial microcirculation.
abstract: To assess the direct cerebrovascular effects of ropivacaine, we studied pharmacological responses to its topical and intravenous (IV) administration on vasomotor tone of pial vessels in in vivo experiments using a parietal cranial window in 24 dogs anesthetized with pentobarbital. We directly measured the diameters of pial arteries and veins after the administration of five different concentrations of ropivacaine solution (10(-7) to 10(-3) mol/L) randomly given into the window (n = 10). In six dogs, after pretreating the pial vessels with yohimbine (10(-5) mol/L), the inhibitory action of yohimbine was examined after the application of ropivacaine (10(-3) mol/L). The effects of IV ropivacaine (1 and 4 mg/kg) were also evaluated in the remaining eight dogs. Ropivacaine produced significant constriction of the pial arteries in a concentration-dependent manner (10(-7) to 10(-3) mol/L, P < 0.05) and only exerted a constrictive action on small veins (P < 0.05) at 10(-3) mol/L. Yohimbine had no effect on ropivacaine-induced constriction of pial vessels. IV ropivacaine, 4 mg/kg but not 1 mg/kg, caused pial vascular constriction (large arteries P < 0.005, small arteries P < 0.0001, large veins P < 0.01, small veins P < 0.005) associated with decrease in heart rate (P < 0.001). The results indicate that topical application of ropivacaine constricts pial arterial vessels in a concentration-dependent manner. A large dose of IV ropivacaine produced pial vasoconstriction associated with a decrease in heart rate and no decrease in mean arterial blood pressure. These effects do not appear to be mediated via the mechanism that depends on the activation of alpha2-adrenoceptors. We conclude that ropivacaine in high concentrations could, perhaps directly, cause significant constriction of the central nervous system vasculature.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Gifu University School of Medicine and Gifu Social Insurance Hospital, Kani City, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ishiyama
authors.forename: S
authors.initials: S
authors.lastname: Dohi
authors.forename: H
authors.initials: H
authors.lastname: Iida
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D000287:Administration, Topical; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000577:Amides / Q000008:administration & dosage / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D007275:Injections, Intravenous; D008833:Microcirculation / Q000187:drug effects; D010841:Pia Mater / Q000098:blood supply* / Q000187:drug effects; D000077212:Ropivacaine; D014661:Vasoconstriction / Q000187:drug effects; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000577:Amides; D000779:Anesthetics, Local; D015016:Yohimbine; D000077212:Ropivacaine