Uridine uptake by nerve cells of the grivet monkey and its relation to cytoplasmic ribonucleic acid concentration

Following intravenous injection of tritiated uridine to a grivet monkey, the uptake in nerve cell nuclei was determined autoradiographically in different brain regions, in the choroid plexus, liver and kidney. It is shown (1) that there are obvious differences in the labelling in different brain areas, and (2) that the labelling, compared with earlier results in mice, is the same in some regions but different in others. The uridine labelling was inversely related to the microspectrophotometrically determined cytoplasmic concentration of ribonucleic acid. This might indicate that cells with a high uridine count and a low cytoplasmic ribonucleic acid concentration have a high metabolic activity.