Abstract
Background: The mechanism of isoflurane-induced cerebral hyperemia is poorly understood. Data from studies in vitro suggest that volatile anesthetics release a vasodilator prostanoid. We hypothesized that prostanoids and nitric oxide (NO) are mediators of this response in vivo. If true, inhibition of cyclooxygenase by indomethacin (5 mg/kg intravenously) or of nitric oxide synthase by N(ω)-nitro-L-arginine methyl ester (L-NAME; 40 mg/kg intravenously) should attenuate isoflurane-induced hyperemia. Any response to L-NAME occurring via nitric oxide should be competitively reversed by L-arginine. Methods: The cerebral blood flow (microsphere) response to 1 MAC isoflurane was tested at three time points (0, 90, and 180 min) in pentobarbital-anesthetized pigs. Isoflurane challenges were separated by 60-min periods of continuous intravenous pentobarbital alone. Control animals (n = 7) received no additional pharmacologic intervention. Experimental animals were randomized to receive L-NAME before the second and indomethacin before the third isoflurane challenge (n = 7); L-NAME before the second and L-arginine (400 mg/kg intravenously) before the third isoflurane challenge (n = 9); or indomethacin before the second and L-NAME before the third isoflurane challenge (n = 8). Results: In control animals, isoflurane reproducibly increased cerebral blood flow (whole brain; 113 ± 18%, 120 ± 18%, and 103 ± 19% increase above baseline at each time point, respectively). Both indomethacin and L-NAME attenuated (10 ± 10% and 52 ± 11% increase, respectively) the hyperemic response to isoflurane. The effect of L-NAME was reversed by L-arginine. Conclusions: We conclude that both prostanoids and nitric oxide contribute to isoflurane-induced hyperemia. We are unable to determine from our data what, if any, interaction exists between these two mechanisms.
Original language | English (US) |
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Pages (from-to) | 1328-1337 |
Number of pages | 10 |
Journal | Anesthesiology |
Volume | 80 |
Issue number | 6 |
DOIs | |
State | Published - 1994 |
Externally published | Yes |
Keywords
- Anesthetics, gases: nitric oxide
- Anesthetics, volatile: isoflurane
- Brain: cerebral blood flow; cerebral metabolic rate of oxygen consumption
- Inhibitors, cyclooxygenase: indomethacin
- Vasodilation: endothelium-dependent
- Vasodilators: prostanoids
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine