Objective To evaluate the effect of intrathecal administration of glycine on the minimum alveolar concentration（MAC）of isoflurane in rats.Methods Intrathecal catheters were implanted in 40 adult male rats anesthetized with isoflurane.Baseline MAC of isoflurane was measured during the infusion of artificial cerebrospinal fluid（CSF）alone.Subsequently

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and 300 mmol/L of glycine dissolved in artificial CSF were infused for two hours at the same rate as under control conditions

and MAC for isoflurane was re-determined.Results Intrathecal administration of glycine produced a significant

dose-dependent decrease in MAC for isoflurane（up to-65.2%±16.2%）.Conclusions Intrathecal administration of glycine decreases anesthetic requirement.This result supports the idea that glycine receptors may be important to the immobilizing effect of anesthetics that enhance glycine receptor function such as isoflurane.