title: Influence of dixyrazine on intestinal and renal vasoconstrictor responses during fentanyl-nitrous oxide anaesthesia.
abstract: In cats (n = 24) anaesthetized with fentanyl-nitrous oxide and diazepam, stimulation of the hypothalamic defence-alarm area (DA) or afferent activation of somatic pain fibres (SA), elicited a pronounced increase in intestinal (DA 297%, SA 107%) and renal (DA 214%, SA 90%) vascular resistance as well as a decrease in diuresis. These stress-related responses were markedly counteracted by dixyrazine (0.15-0.5 mg X kg-1 b.w.i.v.), especially in the kidney where the subsequent increase in vascular resistance to DA and SA stimulations amounted to only 25% and 13%, respectively, while diuresis increased. Corresponding data for stimulation-induced increases in intestinal vascular resistance after dixyrazine were DA 156% and SA 28%. Dixyrazine is suggested to act both through interaction with peripheral alpha-adrenergic mechanisms in control of vascular tone and through central nervous cardiovascular reflex depression. In man (n = 7), during a similar form of anaesthesia, portal vein blood flow (1137 +/- 177 ml) was measured by the continuous thermodilution method. Preportal tissue vascular resistance during surgery decreased significantly (11.3 vs 8.7 kPa X min X ml-1 X 10(-3] after i.v. dixyrazine (0.15 mg X kg-1 b.w.). A concomitant increase in oxygen uptake in preportal tissues occurred (19.9 ml min-1 vs 24.5 ml X min-1).
mesh_terms: D000368:Aged; D000771:Anesthesia, Intravenous; D000818:Animals; D002415:Cats; D004305:Dose-Response Relationship, Drug; D005283:Fentanyl / Q000494:pharmacology*; D006801:Humans; D007583:Jejunum / Q000098:blood supply*; D007668:Kidney / Q000098:blood supply*; D008875:Middle Aged; D009609:Nitrous Oxide / Q000494:pharmacology*; D010640:Phenothiazines / Q000494:pharmacology*; D011169:Portal Vein; D012039:Regional Blood Flow; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D010640:Phenothiazines; C012950:dixyrazine; D009609:Nitrous Oxide; D005283:Fentanyl