Published online before print December 9, 2002, doi: 10.1161/01.HYP.0000046924.94886.EF
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(Hypertension. 2003;41:640.)
© 2003 American Heart Association, Inc.
Scientific Contributions |
Characterization of an Animal Model of Postmenopausal Hypertension in Spontaneously Hypertensive Rats
From the Department of Physiology and Biophysics, The University of Mississippi Medical Center (L.A.F., H.Z., J.F.R.), Jackson, Miss; Department of Pathology, Johns Hopkins University Medical Center (L.R.), Baltimore, Md; and Department of Pharmacology, Vanderbilt University School of Medicine (L.J.R.), Nashville, Tenn.
Correspondence to Jane F. Reckelhoff, PhD, Department of Physiology and Biophysics, University of Mississippi Medical Center, 2500 N State St, Jackson, MS 39216-4505. E-mail jreckelhoff{at}physiology.umsmed.edu
Blood pressure (BP) increases in postmenopausal women. The mechanisms responsible are unknown. The present study was performed to characterize a model of postmenopausal hypertension in the rat and to determine the role that oxidative stress may play in mediating the postmenopausal hypertension. Spontaneously hypertensive rats were ovariectomized (ovx) or left intact (PMR) at 8 months and were aged to 18 months. These animals were compared with young females (YF; 4 or 8 months of age) and old males (18 months) for some measurements. Estradiol levels were decreased in PMR rats to levels not different from YF rats in proestrous or from old males. BP increased progressively with age in PMR rats but not in ovx or male rats, such that the gender difference in hypertension disappeared by 18 months. Glomerular filtration rate was lower in ovx and PMR rats than in YF rats. Renal plasma flow and renal vascular resistance were similar between YF and ovx rats, but lower and higher, respectively, in PMR rats. Serum testosterone increased by 60% in ovx rats and 400% in PMR rats compared with YF rats. Plasma renin activity also increased in PMR rats but not in ovx rats. Chronic treatment (for 8 months beginning at 8 months of age) of PMR rats with vitamins E and C, but not tempol, resulted in a significant reduction in BP and excretion of F2-isoprostanes. In contrast, tempol, but not vitamins E and C, reduced BP in old males. These data suggest that the PMR rats, but not ovx rats, may be a suitable model for the study of postmenopausal hypertension, and that oxidative stress plays a role in the increased BP.
Key Words: women • menopause • oxidative stress • hormones • renin-angiotensin system • nitric oxide
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