Differential labeling with orotic acid and uridine in compensatroy renal hypertrophy
Ross, J.S.; Malamud, D.; Caulfield, J.A.; Malt, R.A.
American Journal of Physiology 229(4): 952-954
1975
ISSN/ISBN: 0002-9513 PMID: 1190338 Document Number: 91315
Using [5-3H]orotic acid and [5-3H]uridine as precursors, the efficiency of labeling and the localization of labeled RNA during compensatory hypertrophy of the mouse kidney were compared. [5-3H]orotic acid in tubules labeled RNA 15 times more intensely than [5-3H]uridine, presumably because of greater incorporation of orotic acid into tubular cells. Of the orotic acid label, 97% was in tubular cells, mostly in the proximal tubules. Only about 80% of the uridine label was in the tubules; the ratio in proximal tubules compared with that in distal tubules was 2:1. No changes in distribution within the nephron were produced during compensatory hypertrophy. [5-3H]uridine should be used as the precursor if generalized labeling is desired, but [5-3H]orotic acid is the better precursor of RNA for many studies of compensatory hypertrophy since it is more efficient and concentrates in the segments of greatest biologic activity.