TY - JOUR
T1 - Evidence that aquaporin-1 mediates NaCl-induced water flux across descending vasa recta
AU - Pallone, Thomas L.
AU - Kishore, Bellamkonda K.
AU - Nielsen, Soren
AU - Agre, Peter
AU - Knepper, Mark A.
PY - 1997/5
Y1 - 1997/5
N2 - Outer medullary descending vasa recta (OMDVR) were perfused in vitro, and volume efflux was measured by driving water movement with transmural gradients of NaCl or albumin. COnsistent with mediation by water channels, p- chloromercuribenzenesulfonic acid (pCMBS) markedly inhibited volume flux induced by NaCl. Dithiothreitol reversed the inhibition. pCMBS did not significantly alter water flux induced by albumin. Osmotic water permeability (P(f)) of the pCMBS-sensitive pathway of glutaraldehyde-fixed and nonfixed OMDVR was 1,102 ± 449 and 1,257 ± 718 μm/s (means ± SD), respectively. pCMBS reduced P(f) to near zero, whereas diffusional water permeability in the same vessels was only slightly inhibited. Immunoreactive aquaporin-1 (AQP1) measured by enzyme-linked immunosorbent assay in collagenase-treated and untreated OMDVR was 5.2 ± 1.0 and 4.2 ± 0.4 fmol/mm, respectively, values that account well for the experimental P(f). We conclude that OMDVR water flux driven by NaCl gradients is most likely mediated by the AQP1 water channel and that NaCl and urea gradients drive water efflux in vivo by this route.
AB - Outer medullary descending vasa recta (OMDVR) were perfused in vitro, and volume efflux was measured by driving water movement with transmural gradients of NaCl or albumin. COnsistent with mediation by water channels, p- chloromercuribenzenesulfonic acid (pCMBS) markedly inhibited volume flux induced by NaCl. Dithiothreitol reversed the inhibition. pCMBS did not significantly alter water flux induced by albumin. Osmotic water permeability (P(f)) of the pCMBS-sensitive pathway of glutaraldehyde-fixed and nonfixed OMDVR was 1,102 ± 449 and 1,257 ± 718 μm/s (means ± SD), respectively. pCMBS reduced P(f) to near zero, whereas diffusional water permeability in the same vessels was only slightly inhibited. Immunoreactive aquaporin-1 (AQP1) measured by enzyme-linked immunosorbent assay in collagenase-treated and untreated OMDVR was 5.2 ± 1.0 and 4.2 ± 0.4 fmol/mm, respectively, values that account well for the experimental P(f). We conclude that OMDVR water flux driven by NaCl gradients is most likely mediated by the AQP1 water channel and that NaCl and urea gradients drive water efflux in vivo by this route.
KW - Aquaporins
KW - Chloride
KW - Kidney
KW - Microcirculation
KW - Raffinose
KW - Sodium
KW - Urinary concentration
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U2 - 10.1152/ajprenal.1997.272.5.f587
DO - 10.1152/ajprenal.1997.272.5.f587
M3 - Article
C2 - 9176368
AN - SCOPUS:0030845197
SN - 0363-6127
VL - 272
SP - F587-F596
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 5 41-5
ER -