Abstract: Exogenous H₂S, in many aspects, had a protective effect on the central nervous system. In preliminary experiment, the administration time and dosage of exogenous H₂S were determined, and then 48 SD rats were randomly divided into four groups, such as control group (CP group), low-dose group (LP group, 7 μmol/kg NaHS), middle-dose group (MP group, 14 μmol/kg NaHS), high-dose group (GP group, 28 μmol/kg NaHS). Animals in three dose groups were randomly administrated 7, 14, 28 μmol/kg NaHS by intraperitoneal injection, followed the administration of ketamine 20 minutes after. The body temperature, heart rate, respiratory rate, blood oxygen saturation and blood pressure were recorded. The results showed that compared to the CP group,body temperatures and blood oxygen saturations in the dose groups significantly increased (P<0.05), heart rates and blood pressures in the dose groups significantly decreased (P<0.05), respiratory rates in the dose groups slowed down, followed a tendency to increase, and these changes showed a significant dose-dependent.

Key words: exogenous H₂S; ketamine; anesthesia; physiological parameters