Urinary excretion of aquaporin-2 water channel during pregnancy.
BACKGROUND
In healthy primiparas the total body water content increases by about 8 liters within the last trimester, with a consequent reduction in plasma arginine-vasopressin (AVP) levels. The aim of the present study was to investigate the effect of normal pregnancy on urinary excretion of AQP2, a vasopressin sensitive water channel.


METHODS
Forty-five healthy pregnant primiparas (specify mean age and range) with a physiological single-fetus pregnancy were studied during weeks 12, 24 and 36 of pregnancy and then for 3 to 5 days postpartum. The control group consisted of 14 age-matched women in the early follicular phase of the menstrual cycle (day 5 or 6). The behavior of plasma AVP, ANP, oxytocin, urinary 6-keto-PGF1alpha (a metabolite of prostacyclin) and urinary AQP-2 excretion were evaluated in all subjects.


RESULTS
Plasma ANP and oxytocin, and urinary AQP-2 and 6kPGF1alpha excretion increased during all three trimesters, with the highest peaks at the 36(th) week. In the postpartum period, these values markedly decreased. No statistically significant changes were found in plasma AVP levels throughout the study period.


CONCLUSIONS
Our findings suggest that a non-AVP factor present in pregnancy plays a role in the control of the excretion of AQP-2 water channels.
Buemi
M
M
Dept. of Internal Medicine, University of Messina, Italy. Asrael@worldmailer.com
D'Anna
R
R
Di Pasquale
G
G
Floccari
F
F
Ruello
A
A
Aloisi
C
C
Leonardi
I
I
Frisina
N
N
Corica
F
F
D015121:6-Ketoprostaglandin F1 alpha / Q000652:urine; D000328:Adult; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000097:blood / Q000652:urine*; D001127:Arginine Vasopressin / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood; D003404:Creatinine; D005260:Female; D006801:Humans; D009994:Osmolar Concentration; D010121:Oxytocin / Q000097:blood; D049590:Postpartum Period; D011247:Pregnancy / Q000097:blood / Q000652:urine*; D011264:Pregnancy Trimesters; D012964:Sodium / Q000097:blood / Q000652:urine; D014556:Urine
C496023:AQP2 protein, human; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D001127:Arginine Vasopressin; D010121:Oxytocin; D015121:6-Ketoprostaglandin F1 alpha; D009320:Atrial Natriuretic Factor; D012964:Sodium; D003404:Creatinine