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H NICOTINE (mg/kg) 



Figure |. Effects of nicotine on FR 32 response rates during the total 30 

 minute session (top) and during the first sijc minutes of the session 

 (bottom). The initial dose-effect functions were determined before 

 chronic nicotine dosing. The redetermined dose-effect functions 

 were determined beginning after 45 days of chronic nicotine^ dosing. 

 . ^ The before group (left side) received nicotine chronica'Hy before 

 the session. The after group (right side) received nicotine chron- 

 ically after the session. Each point represents the. mean: of seven, 

 rats; vertical lines indicate 1 S.E.. Points above C represent 

 control responding; the mean is indicated by 100% on the ordinate. 

 Points above S indicate saline administered twice presession as part 

 of the redetermined dose-effect functions. 



