Abstract
For the purpose of elucidating the physiological significances of intrinsic factor, B_<12> adsorption to intestinal mucosa homogenate of unweaned (aged 48 hours) and adult rats was compared. It was shown that in the unweaned rats, any material having intrinsic factor activity for the intestine of adult or unweaned rats itself was not secreted from stomach. This observation was confirmed by the findings of histological investigation that chief cells of the fundus portion of the stomach was still undeveloped. In these animals, adsorption of B_<12> to intestinal preparation seemed to be independent on intrinsic factor and was not affected by the presence of Ca^<++> ion. On the other hand, omission of Mg^<++> ion reduced the adsorption both in unweaned and adult rats. The amount of B_<12> adsorbed to intestinal preparation of unweaned rats as expressed by μg/kg body weight was from 4 to 10 times greater than that of adult rats. The high capacity of intestinal preparation of unweaned rats to adsorb B_<12>, considered as the first step of B_<12> absorption, may be concerned in efficient B_<12> absorption in unweaned rats. It should be probable that the epitherial cells of small intestine of unweaned rats can uptake indiscriminately various substances which have considerably big molecularsize. The results of the experiment to investigate the effects of bivalent cations on B_<12> adsorption suggested that so-called sequential uptake may occur. (Received June 27,1970)
