67Ga-binding substances in stomach, small intestine, pancreas, and muscle

Normal male rats were injected with either gallium citrate Ga 67 or sodium sulfate S 35. After 24 h, the stomach, small intestine, pancreas, and muscle were excised and homogenized. After the removal of the nuclear fraction, each of these homogenates was digested with protease. After digestion, the supernatants of the reaction mixtures were applied to a Sephadex-G-100 column. The radioactivity was eluted with buffer solution. The resultant eluates were analyzed for radioactivity and the levels of proteins, uronic acids, and sialic acids. In all four organs, sizable amounts of 67Ga were bound to sulfated acid mucopolysaccharides with molecular masses of about 10,000 daltons and to sulfated acid mucopolysaccharides, a species whose molecular masses exceed 40,000 daltons. In the stomach, large amounts of 67Ga were bound to sulfated acid mucopolysaccharides with molecular masses of about 10,000 daltons. From these results, it is obvious that the main 67Ga-binding substances in these four organs are sulfated acid mucopolysaccharides, and that these acid mucopolysaccharides play the most important role in the concentration of 67Ga in these organs.