par Gassee, Jean Pierre ;Decoodt, Pierre ;Verniory, André ;Lambert, Pierre-Paul
Référence American Journal of Physiology, 226, 3, page (616-623)
Publication Publié, 1974
Article révisé par les pairs
Résumé : The curvilinear relationship between the sieving coefficients for polyvinylpyrrolidone 125I (fractional clearances/GFR) and the molecular radii of hydrodynamically equivalent spheres was studied in 42 normal mongrel dogs under Nembutal anesthesia. The parameters characterizing the porosity of an equivalent isoporous membrane, r (radius of cylindrical pores) and Ap/Δx (pore area per unit of path length), were calculated according to sieving equations recently modified on the basis of theoretical studies calculating the drag on a sphere moving in a viscous liquid undergoing a Poiseuille flow inside a cylinder. Effective glomerular filtration pressure (GFPe) has been calculated from the Poiseuille law. The values for r, Ap/Δx, and GFPe have been related to the mean arterial blood pressure (MBP). At MBP levels between 120 and 150 mmHg (group A: n = 22), nonsignificantly different values were calculated: r = 50.2 ± 0.78 Å SEM, Ap/Δx = (1.35 ± 0.1) x 10 5 cm, GFPe = 14.9 ± 0.63 mmHg. At MBP levels above 150 mmHg (group B: n = 20), GFPe was significantly higher (24.2 ± 1.2 Å) and Ap/Δx was significantly lower (0.84 ± 0.007) x 10 5 cm, r remaining unchanged. In 17 dogs (10 from group A, 7 from group B) the aorta was clamped. Autoregulation of GFPe, GFR, and ERPF was present in the first group and almost abolished in the latter. It is suggested that changes in the filtering area contribute to keep GFR constant at increased perfusion pressures.