Summary
The theory of a functional coupling between distal tubular fluid composition and glomerular filtration rate implies that the blockade of flow at a proximal site should lead to a marked increase of GFR. This potential alteration of steady state GFR was studied by comparing the influence of sampling from distal or proximal sites on the filtration rate of identical nephrons. During antidiuresis an average GFR of 25.2 nl/min±7.5 S.D. was found in distal collections, while proximally collected samples gave an average GFR of 34.5 nl/min±8.4 S.D. This difference of 9.3 nl/min is highly significant (p<0.001). During saline diuresis a mean nephron GFR of 41.6 nl/min±5.0 was found by distal sampling and of 45.3 nl/min±5.4 by proximal sampling (p>0.05). The proximal-distal difference in nephron GFR is interpreted to indicate the operation of a tubulo-glomerular feedback control system. Thus, a true steady-state GFR probably cannot be obtained by proximal fluid collection.
Even in the presence of high intratubular pressures and unusually short oil blocks no evidence of sample contamination by retrograde fluid flow past an injected oil block was obtained.
The application of a counter-pressure to the sampling pipette which has been recommended by Gertzet al. [5] as a means to standardize fluid collections, was found to lead to abnormally high intratubular pressures. The reason for this finding appears to be an unexpectedly high and inconstant tip resistance to flow during fluid flow into the pipette.
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Baumann, K., Oelert, H., Rumrich, G., Ullrich, K. J.: Ist Inulin zur Messung des Glomerulumfiltrates beim Warmblüter geeignet? Pflügers Arch. ges. Physiol.282, 238 (1965).
Brenner, B. M., Bennett, C. M., Berliner, R. W.: The relationship between glomerular filtration rate and sodium reabsorption by the proximal tubule of the rat nephron. J. clin. Invest.47, 1358 (1968).
—, Keimowitz, R. L., Wright, F. S., Berliner, R. W.: An inhibitory effect of furosemide on sodium reabsorption by the proximal tubule of the rat nephron. J. clin. Invest.48, 290 (1969).
Führ, J., Kaczmarczyk, J., Krüttgen, C. D.: Eine einfache Methode zur Inulinbestimmung für Nieren-Clearance-Untersuchungen bei Stoffwechselgesunden und Diabetikern. Klin. Wschr.33, 729 (1955).
Gertz, K. H., Braun-Schubert, G., Brandis, M.: Zur Methode der Messung der Filtrationsrate einzelner nahe der Nierenoberfläche gelegener Glomeruli. Pflügers Arch.310, 109 (1969).
Gottschalk, C. W., Morel, F., Mylle, M.: Tracer microinjection studies of renal tubular permeability. Amer. J. Physiol.209, 173 (1965).
Gutman, Y., Gottschalk, C. W., Lassiter, W. E.: Micropuncture study of inulin absorption in the rat kidney. Science147, 753 (1965).
Hilger, H. H., Klümper, J. D., Ullrich, K. J.: Wasserrückresorption und Ionentransport durch die Sammelrohrzellen der Säugetierniere. Pflügers Arch. ges. Physiol.267, 218 (1958).
Horster, M., Thurau, K.: Micropuncture studies on the filtration rate of single superficial and juxtamedullary glomeruli in the rat kidney. Pflügers Arch. ges. Physiol.301, 162 (1968).
Landwehr, D. M., Klose, R. M., Giebisch, G.: Renal tubular sodium and water reabsorption in the isotonic sodium chloride loaded rat. Amer. J. Physiol.212, 1327 (1967).
— Schnermann, J., Klose, R. M., Giebisch, G.: The effect of acute reduction in glomerular filtration rate on renal tubular sodium and water reabsorption. Amer. J. Physiol.215, 687 (1968).
Marsh, D. J., Frasier, C.: Reliability of inulin for determining volume flow in rat renal cortical tubules. Amer. J. Physiol.209, 283 (1965).
Rector, F. C., Sellman, J. C., Martinez-Maldonado, M., Seldin, D. W.: The mechanism of suppression of proximal tubular reabsorption by saline infusion. J. clin. Invest.46, 47 (1967).
Schnermann, J., Horster, M., Levine, D. Z.: The influence of sampling technique on the micropuncture determination of GFR and reabsorption characteristics of single rat proximal tubules. Pflügers Arch.309, 48 (1969).
—, Levine, D. Z., Horster, M.: A direct evaluation of the Gertz hypothesis on single rat proximal tubules in vivo: Failure of the tubular volume to be the sole determinant of the reabsorptive rate. Pflügers Arch.308, 149 (1969).
—, Wright, F. S., Davis, J. M., Stackelberg, W. v., Grill, G.: Regulation of superficial nephron filtration rate by tubulo-glomerular feedback. Pflügers Arch.318, 147 (1970).
Thurau, K., Schnermann, J.: Die Natriumkonzentration an den Macula densa-Zellen als regulierender Faktor für das Glomerulumfiltrat (Mikropunktionsversuche). Klin. Wschr.43, 410 (1965).
Wahl, M., Schnermann, J.: Microdissection study of the length of different tubular segments of rat superficial nephrons. Z. Anat. Entwickl.-Gesch.129, 128 (1969).
Wardener, H. E. de: Control of sodium reabsorption. Brit. med. J.1969 III, 611.
Wunderlich, P., Schnermann, J.: Continuous recording of hydrostatic pressure in renal tubules and blood capillaries by use of a new pressure transducer. Pflügers Arch.313, 89 (1969).
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Schnermann, J., Davis, J.M., Wunderlich, P. et al. Technical problems in the micropuncture determination of nephron filtration rate and their functional implications. Pflugers Arch. 329, 307–320 (1971). https://doi.org/10.1007/BF00588002
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DOI: https://doi.org/10.1007/BF00588002