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The Relative contribution of ER alpha and ER beta to constrictor response of arginine vasopressin during aortic coarctation-induced hypertension in female rats

Jennifer Crawford, Minga Sellers, John Stallone
 VTPP, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX, USA

Abstract Jennifer picture

Objective: To investigate the relative importance of estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) in regulating arginine vasopressin (VP) induced vasoconstriction of mesenteric arteries during development of aortic coarctation-induced hypertension (ACIH) in female rats.

Animals: Age matched ovariectomized female ACIH Sprague-Dawley rats were randomly placed in groups and treated for 14 days with either ERα or ERβ selective agonist. 

Procedure:  ACIH female rats were treated subcutaneously daily with ERα agonist (PPT) or ERβ agonist (DPN); 200μg.  Mean arterial pressures were measured every other day and rats were sacrificed after 12-14 days treatment. 1.5 mm pieces of mesenteric artery were mounted in a Halpern-Mulvany myograph.  Each segment was randomly selected for treatment with: 1) inhibitor of SR calcium release, 2) thromboxane receptor antagonist or 3) vehicle control.  The contractile tension produced by each segment was measured and compared. 

Results:  PPT and DPN treated rats had similar mean arterial pressures.  PPT treated females showed enhanced maximal response to VP, which was attenuated by significantly by SIM and slightly by SQ.

Conclusions and clinical relevance:  Results suggest ERα acts to enhance vascular smooth muscle contraction of mesenteric arteries to vasopressin through upregulation of the thromboxane pathway and intracellular calcium release.

Impact on human and veterinary medicine:  Investigating the individual effects of the estrogen receptors may lead to better understanding of disease processes or markers for various ER related diseases (3, 5).