Ultrafiltration coefficients of glomeruli from human biopsies

Ultrafiltration coefficient (Kf) was measured in vitro using glomeruli isolated from 28 human renal biopsies in order to asses both the relationship between glomerular structure and filtration characteristics and the relationship between Kf and patients' clinical state. The patients, ages 1 to 72 years, had a wide variety of renal diseases and serum creatinines of 1 to 16 mg/dl. Glomeruli were examined by light, immunofluorescence and electron microscopy, and glomerular alterations were measured. Filtration was induced in isolated glomeruli by an oncotic gradient and Kf calculated. Glomerular diameter (D), averaged for each patient, varied from 131 to 315 microns, and Kf varied from 5.7 to 51 nl/min mm Hg. Hydraulic conductivity (Lp) in 15 biopsies averaged 1.45 mu.min-1.mm Hg-1.cm-2. In order to identify the significant predictors of Kf and delineate their relationships, stepwise multiple regression analysis was performed. Kf increased with increasing glomerular size and with increasing degree of glomerular hypercellularity. D, in turn, increased with body surface area, urinary protein, and degree of capillary damage, and decreased with percent senescent glomeruli and degree of epithelial foot process broadening. Kf did not significantly correlate with clinical measures of renal function.