The mobilization and tissue distribution of beta-carotene in the rat by the venous injection method.

Now it is known that beta-carotene (beta-carotene) has other important biological functions in addition to the role of vitamin A precursor. The various epidemiological studies suggested that high beta-carotene intake might reduce the incidence of the cancer risk. Although several studies are under way to find biological evidence for the epidemiological results, the mechanism of action of beta-carotene is still unknown. As the first step to elucidate the biological functions of beta-carotene, we investigated the mobilization and the distribution of all-trans-beta-carotene in the rat. Because it was reported that the rat did not absorb the intact form of beta-carotene, we injected a beta-carotene suspension intravenously (dose; 2.0 mg/rat). After injection, a high amount of beta-carotene (about 1.5 mg-2.0 mg) accumulated in the lung very rapidly (within 5 min). By this method, the time-dependent mobilization and distribution of beta-carotene in the rat was as follows: all-trans-beta-carotene was accumulated in the lung then moved to the liver, was distributed in adipose tissues (after 1 week), pancreas (after 2 weeks), and muscle tissue or testis (after 3 weeks).