Fig. 2.
Chloro-APB induces emergence during continuous isoflurane general anesthesia. (A) Rats inhaled isoflurane at a dose sufficient to maintain loss of righting for a total of 40 min, and received normal saline or the D1 receptor antagonist SCH-23390. Five minutes later, chloro-APB or quinpirole was administered IV. Isoflurane was continued at the same dose until return of righting occurred or 30 min elapsed. (B) For each drug regimen, the percentage of rats that had restoration of righting within 30 min of dopamine agonist administration is shown (n = 6 each). Normal saline alone elicited no arousal response. Rats that received normal saline followed by chloro-APB exhibited restoration of righting in a dose-dependent manner. Pretreatment with the D1 receptor antagonist SCH-23390 (0.2 mg/kg IV) instead of normal saline inhibited restoration of righting by the highest dose of chloro-APB (3 mg/kg IV). Rats that received normal saline followed by the D2 receptor agonist quinpirole did not exhibit restoration of righting. *** Posterior probability greater than 0.99.