title: Glomerular and postglomerular permselectivity to anionic dextrans in the dog.
abstract: Glomerular (G) and postglomerular (PG) capillary permselectivity to anionic dextran markers was investigated using the multiple-indicator-dilution (MID) technique in anesthetized mongrel dogs (n = 14). A bolus of solutes that included sulfated [3H]dextran (SO4d) homogeneous fractions 15.0-28.5 A Stokes-Einstein radius, 125I-albumin (plasma reference), [14C]inulin (G reference), and creatinine (interstitial reference) was injected into the left renal artery. Serial samples of left renal venous and urine outflows were rapidly collected. Sulfated [3H]dextran was 100% recovered, indicating no secretion or reabsorption. The urine recovery of the extracellular indicators was a measure of G extraction (EG). Mean EGSO4d/EGi (+/- SD) ranged from 0.82 +/- 0.03 to 0.48 +/- 0.02 for SO4d's 15.0-28.5 A and was invariant with renal plasma flow (F). These values were 30-50% less than the fractional EG for neutral [3H]dextrans. Postglomerular capillary extraction (EPG) was calculated from the renal vein outflow curve upslope ratios. EPGso4d/EPGcreat varied inversely with F, confirming PG diffusion limitation. Mean permeability-surface area (PS) product ratios PSSO4d/PSi (+/- SD) ranged from 0.98 +/- 0.01 to 0.55 +/- 0.04 for SO4d's 15.0-28.5 A and were consistently larger than values for neutral [3H]dextrans of the same molecular size. In contrast to G charge limitation to anionic solute flux, the PG capillaries demonstrate an increase in apparent permeability to anionic relative to neutral dextrans.
mesh_terms: D000419:Albuminuria / Q000378:metabolism; D000818:Animals; D000838:Anions / Q000378:metabolism; D002199:Capillary Permeability; D003404:Creatinine / Q000097:blood / Q000652:urine; D003911:Dextrans / Q000097:blood / Q000378:metabolism* / Q000652:urine; D004285:Dogs; D005260:Female; D007201:Indicator Dilution Techniques; D007444:Inulin / Q000097:blood / Q000652:urine; D007668:Kidney / Q000098:blood supply; D007678:Kidney Glomerulus / Q000098:blood supply*; D008297:Male; D012082:Renal Veins; D012709:Serum Albumin / Q000032:analysis
chemical_list: D000838:Anions; D003911:Dextrans; D012709:Serum Albumin; D007444:Inulin; D003404:Creatinine