Document Detail

Upregulation of aquaporin 2 water channel expression in pregnant rats.
MedLine Citation:
PMID:  9486978     Owner:  NLM     Status:  MEDLINE    
Water retention is characteristic of pregnancy but the mechanism(s) of the altered water metabolism has yet to be elucidated. The collecting duct water channel, aquaporin 2 (AQP2), plays a pivotal role in the renal water regulation, and we hypothesized that AQP2 expression could be modified during pregnancy. Sprague-Dawley female rats were studied on days 7 (P7), 14 (P14), and 20 (P20) of pregnancy, and expression of AQP2 in papillae was examined. Nonpregnant (NP) littermates were used as controls. Plasma osmolalities were significantly lower in pregnant rats by day 7 of gestation (P7 283.8+/-1.82, P14 284.3+/-1.64, P < 0.001, P20 282. 4+/-1.32, P < 0.0001, vs. NP 291.8+/-1.06 mosmol/kgH2O). However, plasma vasopressin concentrations in pregnant rats were not significantly different than in nonpregnant rats (NP 1.03+/-0.14, P7 1.11+/-0.21, P14 1.15+/-0.21, P20 1.36+/-0.24 pg/ml, NS). The mRNA of AQP2 was increased early during pregnancy: AQP2/beta actin: P7 196+/-17.9, P14 200+/-6.8, and P20 208+/-15.5%, P < 0.005 vs. NP (100+/-11.1%). AQP2 protein was also increased during pregnancy: AQP2 protein: P7 269+/-10.0, P14 251+/-12.0, P < 0.0001, and P20 250+/-13.6%, P < 0.001 vs. NP (100+/-12.5%). The effect of V2 vasopressin receptor antagonist, OPC-31260, was then investigated. AQP2 mRNA was suppressed significantly by OPC-31260 administration to P14 rats (AQP2/beta actin: P14 with OPC-31260 39.6+/-1.7%, P < 0.001 vs. P14 with vehicle) and was decreased to the same level of expression as NP rats receiving OPC-31260. Similar findings were found with the analysis of AQP2 protein. The decreased plasma osmolality of P14 rats was not modified by OPC-31260. The results of the study indicate that upregulation of AQP2 contributes to the water retention in pregnancy through a V2 receptor-mediated effect. In addition to vasopressin, other factors may be involved in this upregulation.
M Ohara; P Y Martin; D L Xu; J St John; T A Pattison; J K Kim; R W Schrier
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical investigation     Volume:  101     ISSN:  0021-9738     ISO Abbreviation:  J. Clin. Invest.     Publication Date:  1998 Mar 
Date Detail:
Created Date:  1998-04-09     Completed Date:  1998-04-09     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7802877     Medline TA:  J Clin Invest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1076-83     Citation Subset:  AIM; IM    
Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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MeSH Terms
Actins / metabolism
Aquaporin 2
Aquaporin 6
Arginine Vasopressin / metabolism
Benzazepines / pharmacology
Blotting, Northern
Blotting, Western
Fluorescent Antibody Technique, Indirect
Gene Expression
Ion Channels / immunology,  metabolism*
Kidney / metabolism
Osmolar Concentration
Pregnancy, Animal / blood,  metabolism*,  urine
RNA, Messenger / metabolism
Rats, Sprague-Dawley
Sodium / metabolism
Vasopressins / metabolism
Water / metabolism
Grant Support
Reg. No./Substance:
0/Actins; 0/Aqp2 protein, rat; 0/Aquaporin 2; 0/Aquaporin 6; 0/Aquaporins; 0/Benzazepines; 0/Ion Channels; 0/RNA, Messenger; 11000-17-2/Vasopressins; 113-79-1/Arginine Vasopressin; 137975-06-5/OPC 31260; 7440-23-5/Sodium; 7732-18-5/Water

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