AJP - Endocrinology and Metabolism, Vol 255, Issue 3 E353-E356, Copyright © 1988 by American Physiological Society
Triton WR-1339 injected into rats enters renal renin granules
B. J. Morris
Department of Physiology, University of Sydney, New South Wales, Australia.
To test directly the possibility that substances in extracellular fluid can
gain access to renin storage granules in renal juxtaglomerular cells, rats
were injected with Triton WR-1339, which binds to plasma proteins. A heavy
granule fraction was prepared, and isopycnic sucrose density gradient
centrifugation was performed. The renin granule peak was found to be
altered from a mean equilibrium density of 1.202 g/ml in control rats to
1.196 g/ml for rats injected with Triton WR-1339 (P less than 0.005). The
distribution of angiotensinogen, which is bound in kidney granules having a
different buoyant density, was also examined and found to be unaltered.
After injection, Triton WR-1339 binds to circulating plasma proteins. The
results for renin support the possibility of pinocytotic uptake of
protein-Triton WR-1339 complexes by the juxtaglomerular cells with
subsequent fusion of the endocytotic lysosomal vacuoles with renin granules
accounting for the translocation of ingested substances into the granule
matrix. If so, the potential would therefore exist for interaction(s) of
ingested extracellular substances with renin or other components in the
granules. The present study has therefore demonstrated directly that
endogenous extracellular substances may enter renin granules.
