TY - JOUR
T1 - Functional characterization and cell immunolocalization of AQP-CD water channel in kidney collecting duct
AU - Fushimi, K.
AU - Sasaki, S.
AU - Yamamoto, T.
AU - Hayashi, M.
AU - Furukawa, T.
AU - Uchida, S.
AU - Kuwahara, M.
AU - Ishibashi, K.
AU - Kawasaki, M.
AU - Kihara, I.
AU - Marumo, F.
PY - 1994
Y1 - 1994
N2 - Vasopressin-regulated water permeability of the kidney collecting duct is a key component of the urine concentration machinery. Recently, a cDNA for AQP-CD, the vasopressin-regulated water channel, initially reported as WCH- CD has been isolated (K. Fushimi, S. Uchida, Y. Hara, Y. Hirata, F. Marumo, and S. Sasaki, Nature Lond. 361:549-552, 1993). AQP-CD was expressed in oocyte membrane using a Xenopus expression vector, and functional characteristics of AQP-CD were examined. Osmotic water permeability (P(f)) of oocytes expressing AQP-CD was 138 ± 19 μm/s (mean ± SE), 12 times greater than the control (11 ± 3 μm/s), 90% inhibited by 0.3 mM HgCl2, and weakly temperature dependent (energy of activation for P(f) was 4.0 kcal/mol). Urea influx measured from 15-min [14C]urea uptake by oocytes injected with AQP- CD/expression vector 1 cRNA was 86 ± 17% of the control. Two-electrode voltage-clamp experiments revealed insignificant ion conductance of AQP-CD. Immunoblots of membranes from rat kidney medulla and oocytes expressing AQP- CD using anti-AQP-CD COOH-terminal antibody showed a 29-kDa protein and 35- to 50-kDa high-molecular-mass forms. Immunohistochemistry showed apical and subapical localization of AQP-CD in the collecting duct principal cells. Our results indicated that AQP-CD is a 29-kDa protein, a selective water channel, distinct from a urea channel, and localized to the membranes of vasopressin- sensitive components in kidney collecting duct principal cells.
AB - Vasopressin-regulated water permeability of the kidney collecting duct is a key component of the urine concentration machinery. Recently, a cDNA for AQP-CD, the vasopressin-regulated water channel, initially reported as WCH- CD has been isolated (K. Fushimi, S. Uchida, Y. Hara, Y. Hirata, F. Marumo, and S. Sasaki, Nature Lond. 361:549-552, 1993). AQP-CD was expressed in oocyte membrane using a Xenopus expression vector, and functional characteristics of AQP-CD were examined. Osmotic water permeability (P(f)) of oocytes expressing AQP-CD was 138 ± 19 μm/s (mean ± SE), 12 times greater than the control (11 ± 3 μm/s), 90% inhibited by 0.3 mM HgCl2, and weakly temperature dependent (energy of activation for P(f) was 4.0 kcal/mol). Urea influx measured from 15-min [14C]urea uptake by oocytes injected with AQP- CD/expression vector 1 cRNA was 86 ± 17% of the control. Two-electrode voltage-clamp experiments revealed insignificant ion conductance of AQP-CD. Immunoblots of membranes from rat kidney medulla and oocytes expressing AQP- CD using anti-AQP-CD COOH-terminal antibody showed a 29-kDa protein and 35- to 50-kDa high-molecular-mass forms. Immunohistochemistry showed apical and subapical localization of AQP-CD in the collecting duct principal cells. Our results indicated that AQP-CD is a 29-kDa protein, a selective water channel, distinct from a urea channel, and localized to the membranes of vasopressin- sensitive components in kidney collecting duct principal cells.
KW - osmotic water permeability
KW - urine concentration
KW - vasopressin
KW - water channel of collecting duct
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U2 - 10.1152/ajprenal.1994.267.4.f573
DO - 10.1152/ajprenal.1994.267.4.f573
M3 - Article
C2 - 7524358
AN - SCOPUS:0027937951
SN - 0363-6127
VL - 267
SP - F573-F582
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
IS - 4 36-4
ER -