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  • 1
    Electronic Resource
    Electronic Resource
    Étude chez le rat des variations du débit individuel de filtration glomérulaire des néphrons superficiels et profonds en fonction de l'apport sodé (1970)
    Springer
    Pflügers Archiv 317 (1970), S. 141-156 
    Details
    ISSN: 1432-2013
    Keywords: Single Nephron Filtration Rates ; High, Normal and Low Sodium Diet ; Heterogeneity of Nephron Function ; Structure and Function ; Einzelnephronfiltrat ; Höhe, Normal und Niedridge Kochsalzdiät ; Unterschiede der Nephronfunktion ; Struktur und Funktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La distribution intrarénale des débits de filtration glomérulaire par néphron (fg) est étudiée en fonction de l'apport sodé chez trois groupes de rats: normaux, carencés en sodium et surchargés en sodium. Les fg ont été déterminées soit indirectement par la méthode de Hanssen soit grâce à une modification de cette méthode qui procure directement les valeurs absolues [23]. Chez les rats normaux, la fg est égale à 27,9 nl/min pour les néphrons superficiels et à 38,5 nl/min pour les néphrons juxtamédullaires. Il n'existe pas de différence décelable entre les fg de nos rats sans sel et celles de nos rats normaux. Chez les rats surchargés en sel, les fg des néphrons superficiels et juxtamédullaires passent respectivement à 52,4 nl/min et à 52,7 nl/min. Au cours de nos surcharges sodées l'augmentation de filtration glomérulaire du rein résulte donc d'une augmentation de la fg de tous les néphrons. Celle-ci est cependant nettement plus marquée pour les néphrons superficiels et le rapport fg néphrons superficiels/fg néphrons juxtamédullaires qui est de 0,7 environ chez les rats normaux et sans sel, atteint 1,0 au cours de nos surcharges sodées. Ainsi dans cette dernière condition physiologique l'hétérogénéité fonctionnelle des néphrons disparaît. La variation des fg est discutée en fonction de ce que l'on sait de la variation de la distribution intrarénale de la rénine sous l'influence de l'apport sodé.
    Notes: Summary The intrarenal distribution of single glomerular filtration rates (SGFR) was studied in rats previously fed a normal or a low sodium diet during antidiuresis, or in rats previously fed a high sodium diet during hypertonic saline diuresis. SGFR were determined either indirectly by Hanssen's technique, or directly by means of a modification of this technique which gives absolute values [23]. In the normal rats, the mean value of SGFR of superficial and juxtamedullary nephrons was equal to 27.9 nl/min and 38.5 nl/min, respectively. There was no appreciable difference between SGFR in our normal and salt-deprived rats. In the salt-loaded rats, the mean value of SGFR of superficial and juxtamedullary nephrons reached 52.4 nl/min and 52.7 nl/min, respectively. Therefore, the increase of the GFR of the whole kidney during salt loading was due to an increase of SGFR of all the nephrons. However, the increase of SGFR was more important for the superficial ones and the ratio SGFR superficial nephrons/SGFR juxtamedullary nephrons which was 0.7 in the normal rats reached 1.0 in the salt-loaded rats, indicating that there was no more functional heterogeneity of nephrons during our salt loadings. The variation of SGFR is discussed in relation to the sodium dependent variation of the intrarenal distribution of renin observed by many authors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592498
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  • 2
    Electronic Resource
    Electronic Resource
    Micropuncture study of water and electrolyte movements along the loop of henle in Psammomys with special reference to magnesium, calcium and phosphorus (1973)
    Springer
    Pflügers Archiv 344 (1973), S. 309-326 
    Details
    ISSN: 1432-2013
    Keywords: Micropuncture ; Mg, Ca and P Excretion ; Concentrating Mechanism ; Loop of Henle ; Electron Probe Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cortical and papillary micropuncture experiments were carried out on Psammomys undergoing mild hypertonic salt diuresis. Tubular fluid was collected along the proximal tubule or at the early distal tubule level, and at the tip of the longest Henle loop.3H-inulin, Na, K, Cl, Mg, Ca and P concentrations, as well as osmotic pressure, were determined in all samples. The results indicate a) no large net water movement along the loop; b) substantial addition of Na, K, Cl, Mg, and to a lesser extent Ca, along the descending limb, in proportion to the gradient; c) the tubular flow rate of phosphorus remains constant at the tip of the loop irrespective of the gradient. The constancy of the load of Na, K, Cl, Mg and Ca delivered to the distal superficial nephron, irrespective of the urinary osmotic pressure, indicates that medullary recycling between the ascending and descending limbs exists for Mg, Cl, and Ca, and confirms its existence for Na and K. In contrast, phosphorus behaves like inulin along the descending limb. A general conclusion is that in Psammomys the concentrating process along the descending limb of Henle results mainly from net addition of solutes, and not from water withdrawal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592784
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  • 3
    Electronic Resource
    Electronic Resource
    Functional heterogeneity of nephrons (1969)
    Springer
    Pflügers Archiv 308 (1969), S. 260-276 
    Details
    ISSN: 1432-2013
    Keywords: Kidney Tubules ; Single Nephron Filtration Rates ; Heterogeneity of Nephron Function ; Structure and Function ; Nierentubuli ; Einzelnephronfiltrationsrate ; Unterschiede der Nephronfunktion ; Struktur und Funktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Non-diuretic rats and saline diuretic psammomys received 0.05 ml14C Na ferrocyanide i.v. Their kidneys were frozen in vivo 8–10 sec later. The quantity of14C ferrocyanide precipitated as prussian blue (Hanssen) in the lumen of a microdissected proximal tubule was proportional to its glomerular filtration rate (gfr). Distance between dye front and glomerulus was proportional to mean flow velocity (v). Fractional water reabsorption at the dye front was calculated using gfr, v and luminal radius. There were large differences in gfr, v and fractional water reabsorption between superficial and deep nephrons. Published micropuncture data agrees quantitatively with our results. Glomerular volume, tubular length and luminal radius increased from superficial to juxtamedullary proximal tubules in both species. Filtration rate varied directly with glomerular volume suggesting an influence of capillary surface area on filtration. Tubular length and luminal radius correlated with gfr. Proximal water reabsorption rate correlated with luminal radius in psammomys but not in rat tubules. Water reabsorption by the entire proximal tubule decreased with length in rat tubules but increased in psammomys. The discrepancy may be due to differences in blood flow distribution which alter gfr and/or water reabsorption in superficial relative to deep nephrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586558
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  • 4
    Electronic Resource
    Electronic Resource
    Role of sodium and urea in the renal concentrating mechanism inPsammomys obesus (1976)
    Springer
    Pflügers Archiv 361 (1976), S. 107-114 
    Details
    ISSN: 1432-2013
    Keywords: Concentrating mechanism ; Loop of Henle ; Vasa recta ; Counter-current system ; Desert rodent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Micropunctures were performed at the tip of Henle's loops and vasa recta accessible at the extrarenal surface of the papilla in a desert rodent (Psammomys obesus) studied under mild NaCl (NaCl 4%, 0.0375 ml/min) and mild urea (urea 4%, 0.0375 ml/min) loading conditions. In NaCl loaded animals, it was confirmed that solute addition (mainly sodium) contributes in a large proportion to the concentrating process along the thin descending limb. Comparison of sodium and urea concentrations in the loops with those in vasa recta at the same level of the papilla demonstrated that 1. the transepithelial sodium gradient was compatible with a diffusion transport of this ion from the interstitium to the thin descending limb; 2. the sodium concentration higher in interstitium than in the loop fluid was not compatible with the existence of a purely passive concentrating process in inner medulla as was recently proposed [8], 3. the transepithelial urea gradient was very limited which indicates that this solute does not play an important part in the concentrating process. In urea loaded psammomys, solute addition (mainly urea) to the thin descending limb fluid was still present but water abstraction was enhanced as compared to salt loaded animals, probably on account to the higher interstitial urea concentration. It is, thus, brought to evidence that the relative contribution of water abstraction and solute addition to the concentrating process along the thin descending limb can vary in a given species as a function of the physiological state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583453
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  • 5
    Electronic Resource
    Electronic Resource
    Phosphate reabsorption in juxtamedullary nephron terminal segments (1980)
    Springer
    Pflügers Archiv 387 (1980), S. 27-31 
    Details
    ISSN: 1432-2013
    Keywords: Renal phosphate reabsorption ; Terminal nephron ; Juxtamedullary nephron ; Loop of Henle ; Microinjection techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Adult Munich Wistar rats undergoing mild salt diuresis (NaCl 20 g·l−1, 0.1 ml·min−1) were injected with tracer doses of3H-Inulin and32P-sodium phosphate in thin descending and ascending limbs of Henle's loop, collecting ducts accessible at the surface of the papilla and early distal superficial tubules. Kidneys were prepared for simultaneous papillary microinjection and urinary flow collection. Expressed in percent of the amounts injected, unidirectional phosphate reabsorption fluxes were 5±1% and 3±1% for injections into early distal superficial tubules and collecting ducts, respectively. By contrast, the flux was 21.7±3% for injections into either the descending or ascending thin limbs of juxtamedullary nephrons. We conclude from these results that in the rat, a significant amount of phosphate is reabsorbed by the juxtamedullary distal tubules and/or the subsequent arcades connecting the juxtamedullary distal tubules to the collecting ducts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580840
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