Objective: To explore the effect positions of the volatile anesthetic inhibiting the nociceptive reflex in the central nervous system.
Methods: Thirty adult SD rats were randomly and equally divided into two groups that the lip and hind paw of rats were held by clamp. The minimum alveolar concentration (MAC) was determined by clamping two places: one was to clamp the hind paw of rats, of which the nervous reflex is controlled via the spinal cord; the another group was to clamp the lip of rats, of which the nervous reflex is controlled through the brain stem.
Results: The isoflurane MAC was 1.44% +/- 0.09% in clamping the hind paw group, while 1.29% +/- 0.11% for clamping the lip group (P < 0.05).
Conclusion: Both brain stem and spinal cord are the effect positions of volatile anesthetics (especially isoflurane).