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-Estradiol deficiency reduces potassium excretion in an angiotensin type 1 receptor-dependent manner
1 Center for the Study of Sex Differences in Health, Aging and Disease, Georgetown University, Washington, District of Columbia, United States; Medicine, Georgetown University, Washington, District of Columbia, United States
2 Center for the Study of Sex Differences in Health, Aging and Disease, Georgetown University, Washington, District of Columbia, United States
3 Center for the Study of Sex Differences in Health, Aging and Disease, Georgetown University, Washington, District of Columbia, United States; Physiology, Georgetown University, Washington, District of Columbia, United States
4 Center for the Study of Sex Differences in Health, Aging and Disease, Georgetown University, Washington, District of Columbia, United States; Medicine & Physiology, Georgetown University, Washington, District of Columbia, United States
* To whom correspondence should be addressed. E-mail: sandberg{at}georgetown.edu.
The study examined the effects of ovariectomy (OVX) and 17
-estradiol (E2) replacement (OVX+E2) on renal function in Sprague Dawley rats. Ovariectomy caused a 40% decrease in the fractional excretion of potassium (FEK+) that was prevented by E2 replacement [%: Sham, 24.2±2.9; OVX, 14.5±2.1*; OVX+E2, 26.2±2.7, n=7-11, *p<0.05 vs OVX+E2] and which corresponded to significant increases in plasma potassium [mmol/L: Sham, 3.15±0.087; OVX, 3.42±0.048*; OVX+E2, 3.19±0.11, n=7-11, *p<0.05 vs OVX+E2]. No effects of ovariectomy were detected on plasma levels of sodium and aldosterone. Angiotensin type 1 receptor (AT1R) densities in ovariectomized rats were 1.4-fold and 1.3-fold higher in glomerular [Bmax (fmol/mg protein): Sham, 482±21; OVX, 666±20*; OVX+E2, 504±26, n=7-11, *p<0.05 vs OVX+E2] and proximal tubular [Bmax (fmol/mg protein): Sham, 721±16; OVX, 741±24*; OVX+E2, 569±23, n=7-11, *p<0.05 vs OVX+E2] membranes compared to E2 replete animals, respectively. Both the angiotensin converting enzyme inhibitor captopril and the AT1R antagonist losartan prevented the ovariectomy-induced decrease in the FEK+ and the increase in renal AT1R densities, suggesting that E2 deficiency reduces potassium excretion in an Angiotensin II-AT1R-dependent manner. These findings may have implications for renal function in postmenopausal women as well as contribute to the reasons underlying the age-induced increase in susceptibility to hypertension-associated disease in women.
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  H. Ji, S. Menini, W. Zheng, C. Pesce, X. Wu, and K. Sandberg Role of angiotensin-converting enzyme 2 and angiotensin(1-7) in 17{beta}-oestradiol regulation of renal pathology in renal wrap hypertension in rats Exp Physiol, May 1, 2008; 93(5): 648 - 657. [Abstract] [Full Text] [PDF]
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