Isolation and characterization of a microvascular fraction from rabbit kidney cortex

Collagenasic dispersion of rabbit kidney cortex followed by centrifugation on discontinuous sucrose gradient, allowed the simultaneous isolation of a microvascular fraction and of glomerular and tubular fractions. The microvessels were characterized by an overall diameter of 22 micron and the presence of granular and smooth muscle cells. Measurement of cellular renin activity and the muscle specific enzyme creatine kinase showed that these vessels were arteriolar in nature and that they contained the preglomerular arterioles. The glomerular or tubular contamination rates were assessed by means of enzymatic markers. Thus, in the arterioles, potassium fluoride-resistant acid phosphatase was some 10 times lower than in the glomeruli. The specific tubular enzymes gamma-glutamyl-transpeptidase and alkaline phosphatase were about 20 times lower in the arterioles than in the tubular fraction. The possibility of obtaining these fractions may facilitate many types of study on renal hemodynamic and glomerulo-tubular feedback control.