Fig. 2. Effects of spinal transection and isoflurane on tail-flick and hind paw (HP) withdrawal latencies. ( A ) Mean latencies for the tail-flick reflex in awake ( filled bars ) and isoflurane-anesthetized ( open bars ) rats. Mean awake tail-flick latencies were significantly reduced from baseline (BL) latencies at 3 days after transection (D3), followed by a recovery at 14 days (D14). Before transection, isoflurane (ISO) significantly increased mean tail-flick latencies. After spinal transection and under 0.8 isoflurane, the heat stimulus no longer elicited a tail-flick reflex up to the cutoff latency of 8.0 s. ( B ) Mean latencies for thermal hind paw withdrawal in awake ( filled bars )and isoflurane-anesthetized ( open bars ) rats. Awake withdrawal latencies remained unchanged from baseline after transection. Isoflurane significantly increased withdrawal latency in intact animals before transection. After transection, withdrawal latencies under isoflurane were further increased during the 28-day period. MAC = minimum alveolar concentration. * Significantly increased latencies under isoflurane compared with awake baseline. + Significantly reduced awake latencies compared with awake baseline. ** Significantly increased isoflurane latencies compared with pretransection isoflurane latencies. Error bars = mean ± SD.