Methods Chemicals Nonradiolabeled nicotine and cotinine were purchased from Sigma Chemical Company (St. Louis, MO). All other reagent grade chemicals and high-performance liquid chromatography (HPLC) solvents were purchased from click here Fisher Scientific Co. (FairLawn, NJ). Cigarettes The same brand of nonmentholated and mentholated filtered cigarettes (100��s) were purchased from commercial sources and had the same reported nicotine yield value of 2.2 mg/cigarette. The nicotine content of these cigarettes was determined in our laboratory by a published HPLC method (Fukumoto, Kubo, & Ogamo, 1997) to be 14.58 mg for the regular cigarette and 13.77 mg for the mentholated cigarette. These nicotine content values compare favorably with those of 14.82 mg/regular cigarette and 13.

28 mg/mentholated cigarette reported for the same cigarettes by the American Cancer Society. Smoke Exposure Apparatus The intermittent smoke generation�Cinhalation system was designed by and purchased from the University of Kentucky Tobacco and Health Research Institute and has been described in detail (Griffith & Hancock, 1985; Griffith & Standafer, 1985). The apparatus is designed specifically to simulate the smoking of a single cigarette and was used for mainstream smoke exposure only. Briefly, the rat exposure chambers are contained in a 5 �� 5 �� 30 cm Plexiglas block. Four chambers on one side of the block are positioned opposite four chambers on the other side of the block. Opposite chambers are connected to the same smoke source at the bottom and to an open-end tube at the top of the block.

Smoke to the chambers is divided into four equal fractions, with each fraction going to two opposite chambers. This distribution system provides smoke of the same age and quality to a maximum of eight rats, simultaneously. A wire mesh restrainer is used to hold the rats in place with only their noses protruding into the chamber. The restrainer consists of a Delrin head piece that fits into the exposure chamber, has a foam rubber insert to prevent the loss of smoke and to minimize injury to the rat, and a wire mesh to hold the body of the rat. For the single-cigarette exposure studies, 10 puffs/cigarette were given per day. For the multiple-cigarette exposure studies, 10 puffs/cigarette were given twice daily for 17 cigarettes. The puffs were generated with a frequency of one per minute Anacetrapib and had duration of 2.4 s and a volume of 40 ml. Animals The animal study protocol was reviewed and approved by the Institutional Animal Care and Use Committee and conducted in the College of Pharmacy and Health Sciences Animal Facility at Texas Southern University. Adult male Sprague-Dawley rats (250�C350 g) were housed in stainless steel cages and had free access to food and water.