Effects of dose and interdose interval on conditioned heart rate tolerance to smoking

The effects of an environmental cue and smoking administration on heart rate (HR) responses to smoking were investigated in 2 studies. The 1st study was performed without smoking, to rule out the possibility that the cue manipulations alone could produce HR habituation. Thirty-six male nonsmokers were exposed to 6 trials of a changing or repeating cue (segments of a story on audiotape), followed by a paced-breathing period. HR habituation was not found. In the 2nd study, 40 male smokers smoked 4 puffs every 10 min (small-dose/long-interdose interval [IDI]) or 6 puffs every 5 min (large-dose/short-IDI) in 6 trials. The same repeating or changing cue preceded smoking. Only the repeating-cue, small-dose/long-IDI group developed HR tolerance. Modifying the cue on Trial 6 did not reverse tolerance. The results indicated that (a) tolerance to smoking appears to be subject to conditioning, (b) this effect depends on the dose and IDI, and (c) the observed tolerance is not likely to be a result of the effects of the cue alone. Nonassociative tolerance to smoking a high-dose/short-IDI did not occur in this study.