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Analysis of cortical urea sequestration in rat renal tissue slices

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Summary

In antidiuretic rats plasma urea concentration (P u )was elevated up to 35 mM by intravenous urea loading. In renal cortical tissue (T) water content and unlabeled (u) and 14-C-urea (u *) were determined.

Water content of total renal cortex and of superficial and juxtamedullary layers were not significantly different and were not changed by the elevation ofP u .

In the control group (P u <10 mM), bothT/P u (3.06±0.71;n=29) and plasma specific activity were significantly higher than values forT/P u * (2.20±0.57;n=12) and tissue specific activity, respectively.T/P u andT/P u * were decreased significantly to the same level (1.68±0.35;n=20 and 1.51±0.21;n=7, respectively) atP u >20 mM and plasma and tissue specific activity became equal.

Deproteination of tissue homogenates did not depress 14-C-activity.

JuxtamedullaryT/P u was significantly higher than superficialT/P u .The difference was independent ofP u .

The data suggest, that renal cortical tissue urea concentration is determined (i) by distal tubular fluid urea concentration, which is inversely correlated withP u and (ii) by a constant amount of urea in an extraluminal compartment not readily exchanging.

The mechanism by which urea concentration in this extraluminal compartment is maintained independent ofP u might be urea neogenesis or urea binding to cellular structures or proteins.

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References

  1. 1.

    Armsen, T., Schad, H., Reinhardt, H. W.: Die Konzentrierung des Harnstoffs in der Niere. II. Mikropunktionsuntersuchungen an der Ratte. Pflügers Arch.313, 222 (1969)

  2. 2.

    Beale, R. N., Croft, D.: A sensitive method for the colorimetric determination of urea. J. clin. Path.14, 418 (1961)

  3. 3.

    Carlisky, N. J., Brodsky, W. A., Huang, K. C.: Biosynthesis of urea by the kidney in relation to the mechanism of urea excretion. Fed. Proc.21, 427 (1962)

  4. 4.

    O'Dell, R. M., Schmidt-Nielsen, B.: Retention of urea by frog and mammalian kidney slices in vitro. J. cell. comp. Physiol.57, 211 (1961)

  5. 5.

    Kleinman, L. J., Radford, E. P.: Urea synthesis by rat kidney. Physiologist7, 179 (1964)

  6. 6.

    Kriz, W.: Der architektonische und funktionelle Aufbau der Rattenniere. Z. Zellforsch.82, 495 (1967)

  7. 7.

    Rabinowitz, L.: In: Urea and the kidney, p. 340. Editor: B. Schmidt-Nielsen. Excerpta Medica ICS 195 (1970)

  8. 8.

    Reinhardt, H. W., Schad, H., Armsen, T.: Zur Frage der Harnstoffkonzentrationen in den Kompartimenten der Nierenrinde (Ratte). Tissue slice-study of urea concentration in structures of the renal cortex (rat). Pflügers Arch.307, R74 (1969)

  9. 9.

    Roch-Ramel, F., Chométy, F., Peters, G.: Urea concentrations in tubular fluid and in renal tissue of nondiuretic rats. Amer. J. Physiol.215, 429 (1968)

  10. 10.

    Roch-Ramel, F., Diézi, J., Chométy, F., Michoud, P., Peters, G.: Disposal of large urea overloads by the rat kidney: a micropuncture study. Amer. J. Physiol.218, 1524 (1970)

  11. 11.

    Roch-Ramel, F., Diézi, J., Chométy, F., Michoud, P., Peters, G.: Urea concentrations in tubular fluid and in renal tissue of rats overloaded with urea or with saline solutions. In: Urea and the kidney, p. 333. Editor: B. Schmidt-Nielsen. Excerpta Medica ICS 195 (1970)

  12. 12.

    Roch-Ramel, F., Peters, G.: Intrarenal urea and electrolyte concentrations as influenced by water diuresis and by hydrochlorothiazide. Europ. J. Pharmacol.1, 124 (1967)

  13. 13.

    Saikia, T. C.: Composition of the renal cortex and medulla of rats during water diuresis and antidiuresis. Quart. J. exp. Physiol.50, 146 (1965)

  14. 14.

    Schmidt-Nielsen, B., O'Dell, R.: Structure and concentrating mechanism in the mammalian kidney. Amer. J. Physiol.200, 1119 (1961)

  15. 15.

    Truniger, B., Schmidt-Nielsen, B.: Intrarenal distribution of urea and related compounds: effects of nitrogen intake. Amer. J. Physiol.207, 971 (1964)

  16. 16.

    Truniger, B., Schmidt-Nielsen, B.: Intrarenal distribution and transtubular movement of urea and related compounds. In: Urea and the kidney, p. 314. Editor: B. Schmidt-Nielsen. Excerpta Medica ICS 195 (1970)

  17. 17.

    Ullrich, K. J., Rumrich, G., Baldamus, C. A.: Mode of urea transport across the mammalian nephron. In: Urea and the kidney, p. 175. Editor: B. Schmidt-Nielsen. Excerpta Medica ICS 195 (1970)

  18. 18.

    Valtin, H.: Sequestration of urea and non-urea solutes in renal tissues of rats with hereditary hypothalamic diabetes insipidus: effect of vasopressin and dehydration on the counter current mechanism. J. clin. Invest.45, 337 (1966)

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Schad, H., Reinhardt, H.W. & Armsen, T. Analysis of cortical urea sequestration in rat renal tissue slices. Pflugers Arch. 346, 31–38 (1974). https://doi.org/10.1007/BF00592648

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Key words

  • Urea Infusion
  • Tissue Analysis
  • Urea Sequestration
  • Urea Binding
  • Urea Neogenesis