Peer-reviewed veterinary case report
Pathophysiological role of aquaporin-2 in impaired water excretion.
- Journal:
- Progress in brain research
- Year:
- 2008
- Authors:
- Ishikawa, San-E et al.
- Affiliation:
- Department of Medicine · Japan
- Species:
- rodent
Abstract
In a state of chronic arginine vasopressin (AVP)-induced antidiuresis, the antidiuretic efficacy has been attenuated: a phenomenon known as "AVP escape". We compared the experimental SIADH rats with 1-deamino-8-D-AVP (dDAVP)-excess rats. The SIADH rats, but not the dDAVP-excess rats, showed a marked attenuation of urinary concentrating ability. This is closely associated with diminished up-regulation of aquaporin-2 (AQP-2) mRNA and protein expression. The following in vitro study clarified tonicity-response elements in the 5'-flanking region of AQP-2 gene. There are at least more than two hypertonicity-response elements, and a hypotonicity-response element resided at tonicity-response enhancer (TonE) (-570 to -560bp) in the AQP-2 gene. Hypotonicity directly reduced the cAMP-induced AQP-2 promoter activity by mediating JNK kinase. Reduction in transcriptional regulation of AQP-2 under hypotonic state may support the in vivo finding of AVP escape phenomenon in chronic AVP-induced antidiuresis.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/18655911/