Modification of cerebral laser-Doppler flow oscillations by halothane, PCO2, and nitric oxide synthase blockade. Am J Physiol 1995 Jul;269(1 Pt 2):H114-20
Date
07/01/1995Pubmed ID
7543253DOI
10.1152/ajpheart.1995.269.1.H114Scopus ID
2-s2.0-0029116081 (requires institutional sign-in at Scopus site) 35 CitationsAbstract
We investigated whether nitric oxide (NO) played a role in the generation of cerebrocortical flow oscillations and their modification by hypocapnia, hypercapnia, and halothane administration. Parietal cortical laser-Doppler flow (LDF) was monitored transcranially in anesthetized (barbiturate + 0-1.0% halothane), artificially ventilated, adult male Sprague-Dawley rats. Thirty minutes after infusion of N omega-nitro-L-arginine methyl ester (L-NAME, 20 mg/kg i.v.) mean arterial pressure (MAP) increased from 105 +/- 10 to 132 +/- 15 mmHg (P < 0.02), while mean LDF decreased from 159 +/- 36 to 135 +/- 30 perfusion units (PU, P < 0.05). Oscillations in LDF at a frequency of 6.3-7.8 cycles/min and amplitude of 10% were induced or augmented by L-NAME but not by D-NAME or indomethacin (2 mg/kg i.p.). L-arginine (200 mg/kg) abolished the oscillations post-L-NAME at constant MAP. Sodium nitroprusside infusion (10(-5) M, 5-50 microliters/min) reversed the L-NAME-induced increase in MAP and decrease in mean LDF but did not attenuate the flow oscillations. Hypocapnia post-L-NAME decreased LDF to 110 +/- 20 PU (P < 0.001) and augmented the flow oscillations (amplitude: 11-31%). Hypercapnia (5% CO2) or halothane (0.4-1.0%) suspended the oscillations in the presence of L-NAME. The results suggest that NO synthase activity inhibits cerebrocortical flow oscillations, and NO is not an obligatory mediator of the effects of halothane, hypocapnia, and hypercapnia on oscillatory activity.
Author List
Hudetz AG, Smith JJ, Lee JG, Bosnjak ZJ, Kampine JPMESH terms used to index this publication - Major topics in bold
Amino Acid OxidoreductasesAnimals
Arginine
Blood Pressure
Carbon Dioxide
Cerebrovascular Circulation
Halothane
Laser-Doppler Flowmetry
Male
NG-Nitroarginine Methyl Ester
Nitric Oxide Synthase
Nitroprusside
Oscillometry
Partial Pressure
Rats
Rats, Sprague-Dawley