The effects of varying concentrations and types of volatile anesthetics on neurochemical sequelae of brain ischemia were evaluated in the rat. Rats were assigned to treatment defined by a 3 x 3 design (anesthetic type and dose) with 5 rats/cell. Each group received halothane, enflurane, or isoflurane 0.5, 1.0, or 2.0 MAC (minimal alveolar concentration). This was followed by preischemic plasma glucose sampling, 5 min hypotension (30 mmHg) and 5 min decapitation cerebral ischemia. Preischemia plasma glucose increased with increasing anesthetic concentration and was highest in the isoflurane groups, varying from a low (+/- SD) of 7.19 +/- 1.79 mumol/ml in the 0.5 MAC halothane group to a high of 12.68 +/- 3.65 mumol/ml in the 2.0 MAC isoflurane group. End-ischemic brain lactate correlated with preischemic plasma glucose (r = 0.5, alpha = 0.5). We conclude that increasing concentration of volatile anesthesia with iv phenylephrine blood pressure support produces higher levels of plasma glucose and brain lactate with cerebral ischemia.
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