Effect of glutaraldehyde on renal tubular function

Abstract

In order to further characterize Cl⁻ transport of the thin ascending limb of Henle's loop (TAL), we observed the effects of glutaraldehyde on Na⁺ and Cl⁻ transport in hamster TAL perfused in vitro. We found that 0.1 mol/l glutaraldehyde added either to the lumen or to the bath caused a rapid irreversible reversal of the NaCl diffusion potential. This was mainly accounted for by an inhibition of Cl⁻ permeability (10⁻⁷ cm² s⁻¹) from 93.51±8.39 to 14.89±3.91 (P<0.01,n=9). By contrast, Na⁺ permeability changed little from 34.18±3.27 to 26.56±2.74 (P<0.01,n=6). Glutaraldehyde treatment abolished the halogen-permselectivity of the TAL as determined by the voltage deflection seen upon ionic substitution. Permeabilities for Cl⁻, Br⁻, I⁻, and SCN⁻ relative to Na⁺ were changed from 3.16±0.20, 3.22±0.19, 2.97±0.26 and 4.36±0.36 to 0.38±0.07, 0.35±0.06, 0.36±0.07 and 0.58±0.05, respectively. The effect of glutaraldehyde on the NaCl diffusion potential was dose-dependent in the range from 10⁻⁵ to 10⁻¹ M. The effect was reversible at concentrations lower than 10⁻³ M. Glutaraldehyde did not affect the NaCl diffusion potential of the long-loop descending limb. These observations constitute additional evidence that the mechanism of Cl⁻ transport across the TAL is different from that of Na⁺ transport. Glutaraldehyde might inhibit Cl⁻ transport in the TAL by cross-linking amino acid residues of the proteins essential for halogen transport across this segment.