We measured the nicotine concentrations in tissues after a bolus i.v. administration of [(3)H]nicotine to rats to characterize the distribution profile of nicotine. The kidney showed the greatest distribution of nicotine compared to other tissues including liver, lung, heart, brain, and intestine. We also performed an HPLC assay for the determination of nicotine and its major metabolite, cotinine, and found that cotinine was negligible in the distribution of almost all tissues, except for the kidney and lung. In the kidney, cotinine was detected at a lower level than nicotine, while cotinine tended to be distributed in the lung compared to nicotine. [(3)H]Nicotine was accumulated in renal slices in a concentration dependent fashion, suggesting that the nicotine uptake in the renal tubules could be mediated by a specific transport system. Unlabeled nicotine, cotinine, and quinidine showed potent inhibitory effects on [(3)H]nicotine uptake by renal slices. In contrast, tetraethylammonium (TEA), cimetidine, and N(1)-methylnicotinamide (NMN), which were substrates of renal organic cation transporters, had no effects on the uptake. These findings suggested that a specific transporter was involved in nicotine transport at the basolateral membranes of rat renal tubules, which could mediate the high accumulation of nicotine from blood into the kidney.