摘要：

The distrubutions of -14C (2'- or -labeled), cotinine-14C, and -14C were studied by whole-body autoradiography in and in perfused lung. The compounds were administered either iv, sc, ip, or by inhalation. Blank sections were also incubated with -14C and cotinine-14C in vitro. The distributions were compared in a black (C57BL/6J), brown (C57L/J), and albino (A/HeJ) strain and in CD-1 germ-free . After administration of -14C in vivo, radioactivity was localized in all strains in bronchi, nasal mucosa, salivary gland, Harder's gland, liver, kidney, stomach, spleen, pancreas, intestine, bone, gallbladder, and adrenal medulla. In the pigmented strains, it was also localized in melanin in the eye, brain, and hair. Radioactivity did not accumulate in the bronchi of late-term fetuses or the 1-day-old newborn but was present in the 2-day-old and older. Cotinine-14C and -14C, after iv administration, did not localize in bronchi or nasal mucosa at short time intervals after injection. Frozen sections incubated in vitro did not accumulate either -14C or cotinine-14C in the bronchi; whereas the affinity for melanin was unchanged. Incubation of fresh, nonfrozen lung and perfusion of lung in vitro with -14C produced the same of radioactivity in bronchi as that seen after in vivo administration. Preheating the frozen sections or lungs in a microwave oven before incubation did not change the of radioactivity in the bronchi or other tissues. The of radioactivity in bronchi may be due to metabolism, active , or of ; this mechanism is destroyed by freezing the tissue.

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