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ACUTE MANNITOL AND SALINE VOLUME EXPANSION IN THE RAT: EFFECT ON TRANSEPITHELIAL POTENTIAL DIFFERENCE IN PROXIMAL TUBULES
Author(s) -
Sugo E.,
Györy Á. Z.
Publication year - 1990
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1990.tb01264.x
Subject(s) - mannitol , saline , chemistry , lumen (anatomy) , extracellular fluid , sodium , potential difference , volume expansion , physiological saline , endocrinology , anatomy , medicine , extracellular , biochemistry , organic chemistry , electrode
SUMMARY 1. Transepithelial potential difference (PD te ) of proximal tubules was measured in rats under control conditions (C), and mannitol‐saline and saline extracellular fluid volume expansion (MVE, SVE, respectively) under conditions of normal net lumen to basal sodium transport. 2. PD te was measured in kidneys bathed with Hartmann's solution or covered with mineral oil under both volume‐expanded conditions together with their controls. 3. PD te was significantly lower in kidneys bathed with Hartmann's solution than in those covered with oil. 4. In MVE rats, with mineral oil covering the kidneys, PD te (expressed as mean and s.e.m.) was for the control 2.20 ± 0.05 ( n = 45) mV and MVE 1.97 ± 0.04 ( n = 36) mV, lumen positive, a significant reduction of 10% ( P <0.001). In SVE rats, with mineral oil covering the kidneys, PD te was for C = 2.42 ± 0.05 ( n = 74) mV and SVE = 1.93 ± 0.03 ( n = 67) mV, a significant reduction ( P <0.001) of 20%. 5. According to thermodynamic considerations, neither of these changes is sufficient to explain the 50% inhibition of Na transport measured previously during MVE and SVE with autologous tubular fluid. The present results offer further evidence supporting the idea that the inhibition of Na transport during MVE and SVE is largely due to inhibition of the active Na transporting step.