Tissue distribution of [3H]-nicotine in rats.

This study was conducted in adult male Sprague--Dawley rats to determine the distribution of [3H]-nicotine in blood and tissues following a bolus injection and a constant infusion of pure nicotine. The animals were anesthetized and injected with either 0.5 ml of nicotine solution or given a constant infusion of the same nicotine solution with identical amounts of radioactive nicotine. After sacrifice, blood, brain, trachea, salivary gland, esophagus, lung, heart, liver, fundus, antrum, spleen, pancreas, duodenum, jejunum, ileum, cecum, colon, kidneys, adrenal gland, and testes were collected and measured for radioactivity by scintillation counting. The distribution of nicotine was found highest in kidneys by both routes of administration. Higher accumulations were also found in salivary and adrenal glands, fundus, antrum, duodenum, jejunum, ileum and colon. Retention of nicotine via constant infusion was significantly higher in esophagus, fundus antrum, spleen, cecum, pancreas, testes, heart and muscle when compared with bolus injection. Six-fold increase in retention of blood levels of nicotine were found with constant infusion. (P < 0.05). The results indicate that longer retention of nicotine occurs in blood and other specific tissues such as esophagus, fundus, antrum, spleen, cecum, pancreas, testes, heart and muscle via constant exposure. These data may implicate the predisposition of these tissues to pathologic manifestations.