Peroxidase uptake by renal papillary cells of normal and hypokalemic rats
Panner, B.J.; Rifkin, B.R.
Laboratory Investigation; A Journal of Technical Methods and Pathology 28(3): 305-312
1973
ISSN/ISBN: 0023-6837 PMID: 4693925 Document Number: 60395
Horseradish peroxidase was injected by vein into normal rats and into rats which had developed characteristic renal papillary dense granules after from 2.5 to 5 days on a diet deficient in K. The fate of the injected peroxidase was studied at intervals of 1 min to 48 h. The pathway for initial uptake of peroxidase by both control and deprived rats was mainly across basilar and lateral plasma membranes. After the marker protein was taken into the cytoplasm of controls it appeared in bisilar phagosomes and was rarely visible in sections after 24 h. In rats deprived of K peroxidase appeared within the dense granules of the papillary cells and disappeared more slowly. Appearance of injected peroxidase within the dense granules is further evidence of the lysosomal nature of these cytoplasmic structures characteristic of low blood K. Biochemical estimations of peroxidase content showed no significant difference between control and experimental rats at 1 h, but increased amounts of peroxidase were present in deprived rats from 4 to 24 h after injection. This study provides no evidence for increased vascular permeability in the renal papilla as a possible mechanism for the polyuria seen in rats with low blood K.