Suppressed urinary excretion of aquaporin-2 in an infant with primary polydipsia.
We observed severe overhydration in an 18-month-old Japanese girl with primary polydipsia. The secretion of antidiuretic hormone (ADH) was decreased, and urinary excretion of aquaporin-2, a vasopressin-sensitive water channel protein, was suppressed under basal conditions, but the response of aquaporin-2 to ADH was essentially preserved. These findings suggest that the water channel itself was intact and that overhydration resulting from polydipsia was responsible for the decreased ADH secretion and suppression of the water channel protein.
Matsumoto
T
T
Department of Pediatrics and Child Health, Kurume University, School of Medicine, Fukuoka, Japan.
Takeya
M
M
Takuwa
S
S
Hiquchi
E
E
Fujimatsu
A
A
Maeshiro
H
H
Ito
Y
Y
Kanno
K
K
Sasaki
S
S
Kato
H
H
D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000652:urine*; D002648:Child; D003681:Dehydration / Q000175:diagnosis; D004327:Drinking Behavior; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000188:drug therapy / Q000209:etiology / Q000652:urine; D008279:Magnetic Resonance Imaging; D009994:Osmolar Concentration; D012462:Saline Solution, Hypertonic / Q000627:therapeutic use; D012640:Seizures / Q000209:etiology; D014667:Vasopressins / Q000097:blood / Q000627:therapeutic use / Q000652:urine
C496023:AQP2 protein, human; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D012462:Saline Solution, Hypertonic; D014667:Vasopressins