The Tissue Distribution of Radioactivity Following the Injection of Varying Levels of Fatty Acid Labeled Chylomicrons in the Rat

Abstract

AbstractBelfrage, P., B. Borgström and T. Olivecrona. The tissue distribution of radioactivity following the injection of varying levels of fatty acid labeled chylomicrons in the rat. Acta physiol. scand. 1963. 58. 111–123. — H3‐palmitic acid labeled chylomicrons in doses of 4–124 mg lipid were injected intravenously into rigorously carbohydrate‐fed rats. The radioactivities in blood, liver, adipose tissue, spleen, lungs, kidneys, and muscles were studied. For doses of 4 to 33 mg lipid the disappearance of label from the blood followed an exponential rate which was similar for these doses and corresponded to half‐lives of 2.2 to 3.5 minutes. The maximal radioactivities found in the liver were also similar for these doses and ranged from 40 to 51% of the injected radioactivity. For doses of 64 and 124 mg lipid the disappearance curve was more complex and the label disappeared more slowly from the blood. The maximal radioactivity found in the liver was also decreased. It is concluded that at these doses the system was overloaded. The spleen and the lungs took up significant amounts of chylomicron fatty acids as evidenced by initial peaks in the radioactivity curves for these tissues. The kidneys, the heart, and the muscles showed a slower rise of radioactivity and presumably took up mainly recirculated fatty acids. The adipose tissue also seemed to take up mainly recirculated fatty acids.