title: Effect of systemic administration of L-kynurenine on corticocerebral blood flow under normal and ischemic conditions of the brain in conscious rabbits.
abstract: Kynurenic acid, the only known endogenous antagonist of the excitatory amino acid receptors, exerts neuroprotective effect in focal cerebral ischemia. Kynurenic acid poorly while its bioprecursor, l-kynurenine (L-KYN) completely crosses the blood-brain barrier. The aim of our study was to investigate the effect of intravenous l-KYN (0.3, 1, and 3 mg/kg) on the normal and the unilateral carotid artery occlusion induced ischemic corticocerebral blood flow (cCBF) measured by hydrogen polarography in conscious rabbits. Administration of l-KYN produced a significant increase in the normal cCBF; the peak values were recorded at the dose of 1 mg/kg (187% at 120 and 150 mins. respectively). The cCBF-improving effect of l-KYN was immediate and highly pronounced also in rabbits with carotid occlusion (peak value was 192% at 120 mins. at the dose of 1 mg/kg). Pretreatment with either atropine or Nomega-nitro-L-arginine-methyl-ester (L-NAME) prevented the l-KYN induced enhancement of the normal and the ischemic cCBF alike. It is suggested that the cCBF-increasing effect of l-KYN might be mediated by activation of cholinergic and nitric oxide pathways.
authors.affiliation: Department of Neurology, Albert Szent-Györgyi Medical Centre, University of Szeged, Szeged, Hungary. sas@nepsy.szote.u-szeged.hu
authors.forename: Katalin
authors.initials: K
authors.lastname: Sas
authors.forename: Klára
authors.initials: K
authors.lastname: Csete
authors.forename: László
authors.initials: L
authors.lastname: Vécsei
authors.forename: Julius Gy
authors.initials: JG
authors.lastname: Papp
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002545:Brain Ischemia / Q000209:etiology / Q000517:prevention & control; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007737:Kynurenine / Q000494:pharmacology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D011048:Polarography / Q000379:methods; D011817:Rabbits
chemical_list: D007737:Kynurenine; D001285:Atropine; D019331:NG-Nitroarginine Methyl Ester