Cerebral blood flow in primates is increased by isoflurane over time and is decreased by nitric oxide synthase inhibition

R. W. McPherson, J. R. Kirsch, J. R. Tobin, R. F. Ghaly, R. J. Traystman

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background: Cerebral blood flow (CBF) decreases over time in dogs and goats during volatile anesthesia. In the current study, we determined CBF during administration of isoflurane for 4 h in cynomolgus monkeys. In addition, we determined if nitric oxide (NO) contributes to cerebrovascular tone during isoflurane anesthesia by determining the CBF (microsphere) response to inhibition of NO synthase with N(ω)-nitro-L-arginine methyl ester (L-NAME). Methods: CBF was measured in five monkeys anesthetized with isoflurane (1.0% end-tidal). After 4 h of isoflurane (1.0% = 1 MAC), the effects of intravenous L-NAME (60 mg/kg over 10 min) followed by intravenous L-arginine (600 mg/kg over 10 min) on CBF were measured at constant cerebral perfusion pressure and arterial carbon dioxide tension. Results: CBF was unchanged over time (4 h) in cerebellum but increased by 50 ± 18% in both forebrain and hindbrain (P < 0.05). CBF decreased by 41-48% (P < 0.05) 20 min after L-NAME in forebrain, cerebellum, and hindbrain, at which time brain NO synthase activity was less than 10% of baseline. Twenty minutes after L- arginine, CBF was increased in cerebellum by 32 ± 8% and in forebrain by 41 ± 9% (P < 0.05). The cerebral metabolic rate of oxygen consumption was unaffected by time or by L-NAME or L-arginine. Conclusions: These data demonstrate that CBF increases over time during isoflurane anesthesia in primates. Tonic production of NO contributes to control of CBF in primates during isoflurane anesthesia. Increased CBF by L-arginine after L-NAME supports the hypothesis that L-NAME decreases CBF via a mechanism requiring NO synthesis.

Original languageEnglish (US)
Pages (from-to)1320-1327
Number of pages8
Issue number6
StatePublished - 1994
Externally publishedYes


  • Anesthetics, volatile: isoflurane
  • Blood vessels, vasoconstriction: N(ω)-Nitro-L-arginine methyl ester
  • Brain: cerebral blood flow; cerebral metabolic rate of oxygen consumption
  • L-Arginine
  • Nitric oxide

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine


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