Glomerular size and charge selectivity in the rat as revealed by FITC-ficoll and albumin.
The fractional clearances (theta) for FITC-Ficoll and albumin were estimated in isolated perfused rat kidneys in which the tubular activity was inhibited by low temperature (8 degrees C) and/or 10 mM NH(4)Cl. The Ficoll data were analyzed according to a two-pore model giving small and large pore radii of 46 A and 80-87 A, respectively. The estimated negative charge density was 35-45 meq/l at 8 degrees C. Perfusion with erythrocyte-free solutions of kidneys at 37 degrees C reduced glomerular size and charge permselectivity. Thus the large pore fraction of the glomerular filtrate (f(L)) was 1.64% at 37 degrees C compared with 0.94% at 8 degrees C. The theta for albumin was four times higher at 37 degrees C than at 8 degrees C (0.86% vs. 0.19%, respectively). NH(4)Cl caused further irreversible damage to the glomerular barrier. We conclude that there are no deleterious effects on the glomerular barrier of a reduction in temperature from 37 degrees C to 8 degrees C. Therefore our data seem to disprove the hypothesis of low glomerular permselectivity and transtubular uptake of intact albumin and support the classic concept of a highly selective glomerular barrier.
Ohlson
M
M
Department of Physiology, Göteborg University, SE-405 30 Göteborg, Sweden. maria.ohlson@fysiologi.gu.se
Sörensson
J
J
Haraldsson
B
B
D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002138:Calibration; D004058:Diffusion; D005362:Ficoll / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D005919:Glomerular Filtration Rate; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008954:Models, Biological; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors
D012709:Serum Albumin; C045540:fluorescein 5-isothiocyanate-Ficoll; D000643:Ammonium Chloride; D005362:Ficoll; D016650:Fluorescein-5-isothiocyanate