Reduced capillary density in the myocardium of uremic rats—A stereological study

Reduced capillary density in the myocardium of uremic rats—A stereological study. Using stereological techniques capillaries, interstitium and myocardial fibers were analyzed in perfusion-fixed hearts of subtotally nephrectomized male Sprague-Dawley rats with uremia of 14 months duration (or their sham-operated controls). Uremic rats had higher systolic blood pressure (140 ± 20.3mm Hg vs. 119 ± 6.61mm Hg) and left ventricular weight/body weight ratio (3.37 ± 0.09 mg/kg vs. 2.01 ± 0.12 mg/kg) than controls, and had slight anemia (Hct 35.0 ± 3.16% vs. 40.4 ± 3.3%). Length density (Lv) of capillaries, that is, capillary length per unit myocardial volume, was significantly (P < 0.001) decreased in uremia (2485 ± 264mm/mm3 vs. 3329 ± 194mm/mm3) versus controls. In parallel, surface density and volume density of the capillary lumina were also reduced (7.95 ± 1.69cm3/cm3 vs. 11.4 ± 1.8cm3/cm3) in the uremic rats. We conclude that in experimental uremia, cardiac hypertrophy is not accompanied by a commensurate increase in capillaries.