PLASMA NICOTINE AND COTININE IN TOBACCO-SMOKE EXPOSED BEAGLE DOGS

Nicotine and cotinine were determined in plasma samples from 87 beagle dogs chronically exposed to cigarette smoke with 3 different levels of nicotine. An additional 18 sham-exposed animals were included in the study as controls. Smoke was administered to the animals through permanent tracheostomas via cuffed tracheostomy tubes and was generated from reference cigarettes under standard puffing parameters by ADL-II smoking machines. The dogs were exposed for an average of 2 yr prior to sample collection. The results from blood samples collected at specific intervals in the daily exposure schedules indicated that nicotine may have ben useful as a relative index of smoke exposure. At elevated exposure levels, average blood concentrations were related to the number of cigarettes smoked and the nicotine delivery of the cigarette. Cotinine increased more slowly than nicotine and was also metabolized more rapidly than in humans. The study examined the relationship of plasma nicotine and cotinine with estimated nicotine exposure.