TY - JOUR
T1 - Dynamic alterations of glomerular charge density in fixed rat kidneys suggest involvement of endothelial cell coat
AU - Ciarimboli, Giuliano
AU - Hjalmarsson, Clara
AU - Bökenkamp, Arend
AU - Schurek, Hans Joachim
AU - Haraldsson, Börje
PY - 2003/10/1
Y1 - 2003/10/1
N2 - In a previous paper, we found that low ionic strength (I) reversibly reduced the glomerular charge density, suggesting increased volume of the charge-selective barrier. Because glutaraldehyde makes most structures rigid, we considered the isolated, perfusion-fixed rat kidney to be an ideal model for further analysis. The fixed kidneys were perfused with albumin solutions containing FITC-Ficoll at two different Is (I = 151 and 34 mM). At normal I, the fractional clearance (0) for albumin was 0.0049 (SE -0.0017, +0.0027, n = 6), whereas 0 for neutral Ficoll35.5Å of similar size was significantly higher 0.104 (SE 0.010, n = 5, P < 0.001). At low I, θ for albumin was 0.0030 (SE -0.0011, +0.0018, n = 6, not significant from θalbumin at normal I) and θ for Ficoll 35.5Å was identical to that at normal I, 0.104 (SE 0.015, n = 6, P < 0.01 compared with θalbumin at low I). According to a heterogeneous charged fiber model, low I reduced the fiber density from 0.056 to 0.0315, suggesting a 78% gel volume expansion. We conclude that 1) there is a significant glomerular charge barrier. 2) Solutions with low I increase the volume of the charge barrier even in kidneys fixed with glutaraldehyde. Our findings suggest that polysaccharide-rich structures, such as the endothelial cell coat, are key components in the glomerular barrier.
AB - In a previous paper, we found that low ionic strength (I) reversibly reduced the glomerular charge density, suggesting increased volume of the charge-selective barrier. Because glutaraldehyde makes most structures rigid, we considered the isolated, perfusion-fixed rat kidney to be an ideal model for further analysis. The fixed kidneys were perfused with albumin solutions containing FITC-Ficoll at two different Is (I = 151 and 34 mM). At normal I, the fractional clearance (0) for albumin was 0.0049 (SE -0.0017, +0.0027, n = 6), whereas 0 for neutral Ficoll35.5Å of similar size was significantly higher 0.104 (SE 0.010, n = 5, P < 0.001). At low I, θ for albumin was 0.0030 (SE -0.0011, +0.0018, n = 6, not significant from θalbumin at normal I) and θ for Ficoll 35.5Å was identical to that at normal I, 0.104 (SE 0.015, n = 6, P < 0.01 compared with θalbumin at low I). According to a heterogeneous charged fiber model, low I reduced the fiber density from 0.056 to 0.0315, suggesting a 78% gel volume expansion. We conclude that 1) there is a significant glomerular charge barrier. 2) Solutions with low I increase the volume of the charge barrier even in kidneys fixed with glutaraldehyde. Our findings suggest that polysaccharide-rich structures, such as the endothelial cell coat, are key components in the glomerular barrier.
KW - Charge selectivity
KW - Glomerular permeability
UR - http://www.scopus.com/inward/record.url?scp=0141590358&partnerID=8YFLogxK
U2 - https://doi.org/10.1152/ajprenal.00227.2001
DO - https://doi.org/10.1152/ajprenal.00227.2001
M3 - Article
C2 - 12812917
SN - 1931-857X
VL - 285
SP - F722-F730
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 4 54-4
ER -