DIRECT VISUALIZATION OF RENIN-CELL DISTRIBUTION IN PREGLOMERULAR VASCULAR TREES DISSECTED FROM RAT-KIDNEY

Three methods to visualize directly the distribution of granulated ren in-positive cells in vascular trees microdissected from rat kidney wer e developed. Kidneys were removed from anesthetized rats, hemisectione d, macerated in HCl, and soaked in distilled water for 24-48 h. Cortic al preglomerular vascular trees consisting of arcuate and cortical rad ial arteries and afferent arterioles were microdissected with the aid of a stereomicroscope. Granulated cells can be visualized in three way s. First, under transmitted or incident light observation, granulated cells are readily distinguished from the surrounding smooth muscle cel ls, because of marked differences in the refractive properties of thes e two cell types. Second, quinacrine, a fluorescent, intravital stain selective for dense-core granules, can be administered (2 mg/kg iv) to the rat 1 h before nephrectomy. When illuminated with 440-nm light, g ranulated cells fluoresce strongly at 510 nm. Third, specific immunost aining for renin can be obtained with a poly-clonal anti-rat renin ant ibody and avidin-biotin immunoperoxidase staining in vascular trees su bjected to cell permeabilization with Triton. These new techniques per mit the direct visualization of the distribution of granulated renin-p ositive cells in preglomerular vessels under conditions in which the v ascular architecture is largely preserved.