INSERT FIG. 6 



70 



irg/kg/sc) was administered there was no change in the total (24) nuirber 

 o' infusions. In contrast, tnecanyl amine at a dose of 1.5 og/kg 

 decreased the nunber of infusions by 62S. Increasing the dose of meca- 

 myiair.ine to 3.0 irg/kg decreased responding for nicotine further (Fig. 

 5, solid bars). Responding for nicotine returned to previous levels 

 the Zi h session after the tcc amy 1 amine administrations. Pi-esession 

 treatcent with hexa.'nethoniun (1.5 and 3.0 mg/kg/sc) in the same fofrr 

 rats did not reduce responding (Fig. 5, bars with das*"ed lines). 



The within session pattern cf resoonding following saline ard ;:ieca- 

 mylairine treatment are shown in Fig. 6. The solid line, closed circle 

 function shows the pattern of infusions for 2i h periods in 3 h blocks 

 beginning at 083C h. T^'is pattern was characteristic for all four ani- 

 mals and the largest standard error for any 3 h period was 2.1 

 infusions/S l" block. Tre nuii.ber of infusions during the first 3 h fol- 

 lowirc the 0.75 irecaT.yia.-nire dose was e'evated conpa'-ed to saline lev- 

 els. This was followed by a decrease in infusions in the next 3 h. 

 The number of infusions gradually increased to control values. The num- 

 ber of infusions following the 1.5 mg/kg dcse of mecamylamine initia'ly 

 increased (first 3 h) then decreased to near zero levels for £ o* the 

 rewainirg 3 h intervals. During the last 3 h interval the number of 

 infusions increased by was still below control levels. The 3.0 mg/kg 

 dose decreased the nurber of infusions in all 3 h intervals. The num- 

 ber and pattern of infusions during the next 24 h pen'od did not differ 



12 



