Glomerular filtration in the isolated perfused kidney

Abstract

Glomerular hemodynamics were studied of isolated perfused kidneys of 12-wk-old normotensive (NR) and spontaneously hypertensive (SHR) rats, using Pluronic F108 (BASF, Wyandotte, MI, USA) as a plasma expander. Glomerular filtration rate (GFR), proximal tubular hydrostatic pressure (PT) and glomerular capillary hydrostatic pressure (PGC) were approximately linearly related with renal perfusion pressure. PGC measured directly by micropuncture was comparable to PGC calculated from other parameters of glomerular dynamics using pore theory. We conclude that GFR in isolated kidneys perfused with Pluronic F108 is lower than in vivo, mainly as a result of an increase in PT. This rise in tubular pressure is due to an increased urine flow rate and an elevated tubular fluid viscosity. The difference in glomerular dynamics between NR and SHR kidneys is the result of an increased preglomerular vascular resistance in SHR, possibly due to an adaptive hypertrophic reaction to a sustained hypertension.

Handling of Human Pepsinogens by the Isolated Rat Kidney: Evidence for a High Glomerular Sieving Coefficient

“…however, an increase in colloid osmotic pressure of the perfusate after addition of NalAA (table 1). A similar increase in colloid osmotic pressure has been observed when the molecular size of Pluronic is decreased by low ering the temperature of the solution [12], Therefore, the change in fractional excretion of Pluronic observed in this study does not necessarily represent a change in glomerular permeability but rather suggests an increased glomerular sieving of Pluronic due to a de crease in molecular size in the presence of NalAA. The fractional excretions of PGA and PGC observed in this study, therefore, most likely provide an accurate estimate of the glo merular sieving coefficients.…”

“…8 13.000 dalton. radius 34 A at 37°C) [12]. The perfusion fluids were prepared in sterilized bottles and were filtered immedi ately before use (Millipore.…”

Differential disposition of intra-renal generated and preformed glucuronides: studies with 4-methylumbelliferone and 4-methylumbelliferyl glucuronide in the filtering and nonfiltering isolated perfused rat kidney

“…Male Sprague–Dawley rats (429–570 g), purchased from the IMVS, were maintained at 22–24°C on a 12‐h light/dark cycle with free access to food and water. The filtering IPK preparation employed here was based on previously published methods [33,34] . The perfusion medium consisted of Krebs–Henseleit buffer (pH 7.4) containing Pluronic F108 (2.5 g/l), d ‐glucose (5 mmol/l), l ‐cysteine (0.5 mmol/l), glycine (2.3 mmol/l) and l ‐glutamic acid (0.5 mmol/l).…”

Properties of the Glomerular Barrier and Mechanisms of Proteinuria

“…For example, the kidney can be perfused at normal temperatures (37°C) (30,180,257) or at reduced temperatures [4 -8°C, cooled isolated perfused kidney (cIPK)] (173, 240). As perfusate, one can use blood (33,60,248) or artificial solutions containing albumin (140), dextran (297), or other colloids (38). Tubular modification of the primary urine has been minimized by using chemical agents (222,228), low temperatures (140,213,240,302), and chemical fixation (51)(52)(53).…”