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On the 'tightness' of the rabbit descending limb of the loop of Henle: Physiological and morphological evidence

par Abramow, Maurice ;Orci, Lelio
Référence International Journal of Biochemistry, 12, 1-2, page (23-27)
Publication Publié, 1980

Article révisé par les pairs

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Résumé :

In order to collect direct information on the nature of the countercurrent multiplier we isolated descending limbs of the loop of Henle in the rabbit inner medulla and perfused them in vitro. The transepithelial electrical resistance was high with a mean exceeding 700 Ω cm2 a value typical of tight epithelia. The sodium permeability, calculated from the lumen to bath fluxes of 22Na was very low: 1.7 x 10-6 cm·sec-1. Batches of dissected descending limbs were processed for freeze-fracture electron microscopy. The tight junctions in this segment were characteristic of tight epithelia. Thus functional and morphological evidence indicates that this region of the nephron does not permit free passage of NaCl. These features should facilitate the operation of the countercurrent multiplier according to passive models.