Variation of proximal tubular reabsorptive capacity by volume expansion and aortic constriction during constancy of peritubular capillary protein concentration in rat kidney

1975 ◽  
Vol 356 (1) ◽  
pp. 73-86 ◽  
Author(s):  
H. Holzgreve ◽  
R. W. Schrier ◽  
M. M�ller ◽  
D. Simmen ◽  
R. Stephan
Keyword(s):  
Volume Expansion ◽  
Protein Concentration ◽  
Rat Kidney ◽  
Peritubular Capillary ◽  
Aortic Constriction ◽  
Reabsorptive Capacity ◽  
Proximal Tubular

Exaggerated Phosphaturic Response to Volume Expansion in Patients with Essential Hypertension

1975 ◽  
Vol 49 (3) ◽  
pp. 207-211 ◽  
Author(s):  
C. Chaimovitz ◽  
A. Spierer ◽  
H. Leibowitz ◽  
S. Tuma ◽  
O. S. Better
Keyword(s):  
Volume Expansion ◽  
Chloride Solution ◽  
Sodium Reabsorption ◽  
Water Diuresis ◽  
Diluting Segment ◽  
Hypertensive Patients ◽  
Reabsorptive Capacity ◽  
Proximal Tubular ◽  
Isotonic Sodium Chloride ◽  
Distal Delivery

1. Tubular handling of sodium in hypertensive patients has been evaluated with urinary phosphate excretion used as a marker for proximal tubular reabsorptive capacity. 2. Nine hypertensive patients and nine normal control subjects were studied during sustained water diuresis and the intravenous infusion of isotonic sodium chloride solution to produce volume expansion. 3. In the hypertensive patients there was exaggerated phosphaturia, natriuresis and enhanced distal delivery of sodium. Sodium reabsorption in the diluting segment was normal. 4. The enhanced distal delivery and augmented phosphaturia suggest that a decreased reabsorption of sodium in the proximal tubule is the most likely explanation for the exaggerated natriuretic response to volume expansion in hypertensive patients.

Effects on Rat Kidney Slice Function In Vitro of Proteins from the Urines of Patients with Myelomatosis and Nephrosis

1974 ◽  
Vol 46 (3) ◽  
pp. 283-294 ◽  
Author(s):  
H. G. Preuss ◽  
F. R. Weiss ◽  
R. M. Iammarino ◽  
W. J. Hammack ◽  
H. V. Murdaugh
Keyword(s):  
Deleterious Effect ◽  
Protein Concentration ◽  
Inverse Relationship ◽  
Rat Kidney ◽  
Light Chains ◽  
Urinary Proteins ◽  
Proximal Tubular ◽  
Proximal Tubular Function ◽  
Urine Proteins

1. The effects were investigated of non-dialysable substances obtained from urines of patients with nephrotic syndrome and those with myelomatosis (heavily laden with light chains) on renal function in a system in vitro. 2. The ability of the rat kidney slice to accumulate hippurate and tetraethylammonium (TEA), and to produce ammonia and glucose, was measured after incubation in urine proteins from ten patients with myelomatosis. All slice functions measured at protein concentrations of 10 mg/ml decreased significantly compared with control. Hippurate accumulation averaged 58%, TEA accumulation, 53%, ammoniagenesis, 59%, and gluconeogenesis, 57% of control. An inverse relationship between protein concentration and hippurate accumulation was noted. 3. Slices incubated in proteins from eight nephrotic patients showed no consistent decrease from control in hippurate accumulation (95%), TEA accumulation (103%), ammoniagenesis (91%) or gluconeogenesis (92%). 4. Since urinary proteins from patients with myelomatosis, unlike urinary proteins from the nephrotic patients, had a consistently deleterious effect on the function of renal slices, this suggests that proteins found in urines from myelomatous patients may play a role in the disturbance of proximal tubular function sometimes seen in this disorder.

Inhibition by insulin of cellular autophagy in proximal tubular cells of rat kidney

1983 ◽  
Vol 244 (2) ◽  
pp. E109-E114 ◽  
Author(s):  
U. Pfeifer ◽  
M. Warmuth-Metz
Keyword(s):  
Volume Fraction ◽  
Rat Kidney ◽  
Insulin Dose ◽  
Ringer Solution ◽  
Numerical Density ◽  
Partial Recovery ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Cellular Autophagy ◽  
Proximal Tubular

Adult male Sprague-Dawley rats were injected intraperitoneally with 5 U insulin/kg body wt (45 animals). As determined by quantitative electron microscopy, the volume fraction and the numerical density of autophagic vacuoles (AV) in proximal tubular cells decreased within 10 min by 46 and 26%, respectively. A partial recovery of the AV volume fraction was observed 20 and 30 min after the injection contrary to our previous findings with liver (J. Cell Biol. 78: 152-167, 1978). In an additional experiment (12 animals) it was shown that an insulin dose of 0.5 U but not of 0.05 U/kg body wt reduced the AV volume fraction to an extent similar to that of 5 U. To eliminate possible secondary effects, Ringer solution containing 0.8 microM insulin was dropped intravitally for 15 min to one pole of the decapsulated kidney and Ringer solution without additions to the other pole (8 animals). After intravital fixation, the AV volume fraction and numerical density in proximal tubular cells was found to be reduced under the influence of insulin by 22 and 36%, respectively. This data shows that insulin inhibits the process of cellular autophagy in proximal tubular cells of the kidney.

Contribution of abdomen and legs to central blood volume expansion in humans during immersion

1997 ◽  
Vol 83 (3) ◽  
pp. 695-699 ◽  
Author(s):  
Lars Bo Johansen ◽  
Thomas Ulrik Skram Jensen ◽  
Bettina Pump ◽  
Peter Norsk
Keyword(s):  
Blood Volume ◽  
Volume Expansion ◽  
Protein Concentration ◽  
Water Immersion ◽  
Venous Pressure ◽  
Cuff Inflation ◽  
Central Blood Volume ◽  
Central Venous ◽  
Plasma Protein Concentration ◽  
Blood Volume Expansion

Johansen, Lars Bo, Thomas Ulrik Skram Jensen, Bettina Pump, and Peter Norsk. Contribution of abdomen and legs to central blood volume expansion in humans during immersion. J. Appl. Physiol. 83(3): 695–699, 1997.—The hypothesis was tested that the abdominal area constitutes an important reservoir for central blood volume expansion (CBVE) during water immersion in humans. Six men underwent 1) water immersion for 30 min (WI), 2) water immersion for 30 min with thigh cuff inflation (250 mmHg) during initial 15 min to exclude legs from contributing to CBVE (WI+Occl), and 3) a seated nonimmersed control with 15 min of thigh cuff inflation (Occl). Plasma protein concentration and hematocrit decreased from 68 ± 1 to 64 ± 1 g/l and from 46.7 ± 0.3 to 45.5 ± 0.4% ( P < 0.05), respectively, during WI but were unchanged during WI+Occl. Left atrial diameter increased from 27 ± 2 to 36 ± 1 mm ( P < 0.05) during WI and increased similarly during WI+Occl from 27 ± 2 to 35 ± 1 mm ( P < 0.05). Central venous pressure increased from −3.7 ± 1.0 to 10.4 ± 0.8 mmHg during WI ( P < 0.05) but only increased to 7.0 ± 0.8 mmHg during WI+Occl ( P < 0.05). In conclusion, the dilution of blood induced by WI to the neck is caused by fluid from the legs, whereas the CBVE is caused mainly by blood from the abdomen.

Role of luminal hydrostatic pressure in proximal tubular fluid reabsorption in the rat

1975 ◽  
Vol 229 (3) ◽  
pp. 813-819 ◽  
Author(s):  
A Grandchamp ◽  
Scherrer ◽  
D Scholer ◽  
J Bornand
Keyword(s):  
Hydrostatic Pressure ◽  
Proximal Tubule ◽  
Pressure Difference ◽  
Unit Area ◽  
Rat Kidney ◽  
Fluid Reabsorption ◽  
Proximal Tubular ◽  
Tubular Fluid Reabsorption ◽  
Selective Change

The effect of small changes in intraluminal hydrostatic pressure (P) on the tubular radius (r) and the net fluid reabsorption per unit of surface area of the tubular wall (Js) has been studied in the proximal tubule of the rat kidney. The split-drop method was used to simultaneously determine Js and r. Two standardized split-drop techniques A and B allow selective change in P. P was 31.6 +/- 1.3 mmHg in technique A and 15.5 +/- 1.5 in technique B. The pressure difference significantly affected the tubular radius; r was 21.9 +/- 0.4 and 18.6 +/- 0.5 mum in the split drop A and B, respectively. In contrast, net transepithelial fluid reabsorption Js was unchanged. Js amounted to 2.72 +/- 0.20, and 2.78 +/- 0.33 10(-5) cm3 cm-2 s-1 in split drop A and B. The absence of variations in Js could result from two opposite effects of pressure. P might enhance Js by increased ultrafiltration. However, the rise in r might decrease the density of the intraepithelial transport paths per unit area of tubular wall and therefore might decrease Js.

Renal cortical interstitium and fluid absorption by peritubular capillaries

1994 ◽  
Vol 266 (2) ◽  
pp. F175-F184 ◽  
Author(s):  
K. Aukland ◽  
R. T. Bogusky ◽  
E. M. Renkin
Keyword(s):  
Rat Kidney ◽  
Colloid Osmotic Pressure ◽  
Capillary Wall ◽  
Peritubular Capillary ◽  
Fluid Reabsorption ◽  
Fluid Uptake ◽  
Peritubular Capillaries ◽  
Capillary Fluid ◽  
Renal Cortical Interstitium ◽  
Relative Retardation

Every minute, the cortical peritubular capillaries in a 1-g rat kidney take up more than 0.5 ml tubular reabsorbate. Studies of renal lymph and measurements of pressure in capillaries (Pc) and interstitium (Pi) indicate that normally the protein colloid osmotic pressure of peritubular capillary plasma (COPp) provides the necessary absorptive force, keeping Pi at 2-4 mmHg, i.e., 8-10 mmHg lower than Pc. At reduced COPp, continued delivery of fluid from the tubules automatically raises Pi to maintain capillary fluid uptake. The transient Pi response to sudden exposure of the kidney to subatmospheric pressure shows that such adjustment of forces may take place in only 5 s. Most remarkable, adjustment of forces may take place in only 5 s. Most remarkable, reabsorption continues during protein-free perfusion of the isolated rat kidney, apparently effected by a Pi exceeding Pc. A relative retardation of interstitial uptake of ferritin from plasma in this case suggests fluid reabsorption through both small and large pores in the capillary wall. Collapse of the capillaries is presumably prevented by tight tethering to the capillary wall, giving the narrow interstitium a very low compliance.

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