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Sex Differences in the Pressor and Tubuloglomerular Feedback Response to Angiotensin II.
MedLine Citation:
PMID:  22124434     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Awareness of sex differences in the pathology of cardiovascular disease is increasing. Previously, we have shown a role for the angiotensin type 2 receptor (AT(2)R) in the sex differences in the arterial pressure response to Ang II. Tubuloglomerular feedback (TGF) contributes in setting pressure-natriuresis properties, and its responsiveness is closely coupled to renal Ang II levels. We hypothesize that, in females, the attenuated pressor response to Ang II is mediated via an enhanced AT(2)R mechanism that, in part, offsets Ang II-induced sensitization of the TGF mechanism. Mean arterial pressure was measured via telemetry in male and female wild-type (WT) and AT(2)R knockout (AT(2)R-KO) mice receiving Ang II (600 ng/kg per minute SC). Basal 24-hour mean arterial pressure did not differ among the 4 groups. After 10 days of Ang II infusion, mean arterial pressure increased in the male WT (28±6 mm Hg), male AT(2)R-KO (26±2 mm Hg), and female AT(2)R-KO (26±4 mm Hg) mice, however, the response was attenuated in female WT mice (12±4 mm Hg; P between sex and genotype=0.016). TGF characteristics were determined before and during acute subpressor Ang II infusion (100 ng/kg per minute IV). Basal TGF responses did not differ between groups. The expected increase in maximal change in stop-flow pressure and enhancement of TGF sensitivity in response to Ang II was observed in the male WT, male AT(2)R-KO, and female AT(2)R-KO but not in the female WT mice (P between sex and genotype <0.05; both). In conclusion, these data indicate that an enhanced AT(2)R-mediated pathway counterbalances the hypertensive effects of Ang II and attenuates the Ang II-dependent resetting of TGF activity in females. Thus, the enhancement of the AT(2)R may, in part, underlie the protection that premenopausal women demonstrate against cardiovascular disease.
Authors:
Russell D Brown; Lucinda M Hilliard; Geoffrey A Head; Emma S Jones; Robert E Widdop; Kate M Denton
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-11-28
Journal Detail:
Title:  Hypertension     Volume:  -     ISSN:  1524-4563     ISO Abbreviation:  -     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-29     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Departments of Physiology and Pharmacology, Monash University, Melbourne, Victoria, Australia; Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia.
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