Pflügers Archiv

, Volume 351, Issue 1, pp 1–12 | Cite as

Widening of the paracellular pathway in the kidney tubule by a transtubular osmotic gradient

Passage of graded size non-electrolytes
  • Margarita Pérez-Gonzalez
  • Guillermo Whittembury


Trace amounts of either labelled mannitol, sucrose, raffinose or inulin were added to the portal circulation in the doubly perfused toad kidney and their-urine-to-portal fluid, labelled molecules-to-chemical inulin ratio (denoted here asR) was evaluated. Under control isosmotic conditionsR was found to be inversely related to the probing molecule radius.R for inulin was practically zero.R for all probing molecules rose reversibly when the luminal fluid was rendered hyperosmotic by addition of 50 mmole mannitol to the aortic circulation, and even more so when 50 mmole urea was added per liter of aortic fluid. ThusR for raffinose rose from 0.0025±0.0002 (control) to 0.0126±0.0012 (+50 mM mannitol) and to 0.0967±0.0112 (+50 mM urea). This increase inR must be due to widening of the paracellular shunt pathway since the contribution of portal circulation to the glomerular filtrate was negligible and these molecules are known to stay extracellular. The present experiments suggest that transtubular urea (and osmotic) gradients may play a role in the regulation of the size of the paracellular shunt pathway.

Key words

Paracellular Shunt Pathway Transtubular Permeability Perfused Toad Kidney Transtubular Osmotic Gradient Kidney Epithelia 


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Copyright information

© Springer-Verlag 1974

Authors and Affiliations

  • Margarita Pérez-Gonzalez
    • 1
    • 2
  • Guillermo Whittembury
    • 1
    • 2
  1. 1.Centro de Biofísica y BioquímicaInstituto Venezolano de Investigaciones Científicas (IVIC)CaracasVenezuela
  2. 2.Instituto de Medicina ExperimentalUniversidad Central de VenezuelaVenezuela

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