Human cigarette smoking: manipulation of number of puffs per bout, interbout interval and nicotine dose.

In a residential research ward, cigarette smoking was studied during 12-hr daily sessions in seven volunteer human subjects with histories of regular smoking. Puff-to-puff delivery of cigarette smoke was held relatively constant by instructing and monitoring subjects in taking uniform puffs and by specifying and timing the duration of holding the smoke in the lungs (5 sec) and the duration of the interpuff interval (25 sec). When a modest response requirement of riding a stationary exercise bicycle for 1 min was required before each smoking bout consisting of eight uniform puffs, stable patterns of smoking emerged in which smoking bouts were evenly spaced within and across sessions. When the number of puffs per bout was experimentally manipulated both across and within sessions, increases in puffs ber bout resulted in increases in interbout intervals. When the interbout interval was experimentally manipulated both across and within sessions and the number of puffs per bout was free to vary, increases in interbout interval resulted in increases in puffs per bout. When both nicotine dose (0.2-1.6 mg per cigarette) and puffs per bout were varied across sessions in the same experiment, changes occurred in interbout interval in response to manipulation of puffs per bout but not nicotine dose. Although nicotine dose did not influence interbout interval or puffs per hour, subject ratings of cigarette strength tended to increase with dose.