Key result
Ovariectomy blunts the pressure-natriuresis slope by ~53%, accelerating salt-induced hypertension.
Our objective was to determine whether increased salt sensitivity after menopause precedes the development of overt hypertension. We investigated the effect of ovariectomy on pressure natriuresis in Dahl-Iwai salt-sensitive (DS) and salt-resistant (DR) rats by in vivo perfusion studies. Differences in the neural and hormonal backgrounds of the kidney were minimized by renal denervation and by holding plasma vasopressin, aldosterone, corticosterone, and norepinephrine levels constant by intravenous infusion. The pressure-natriuresis relationship was blunted in DS rats compared with DR rats (slope, 0.30 versus 0.63 mumol.min-1.g kidney wt-1.mm Hg-1, P < .01). The impaired pressure-natriuresis response of DS rats was further blunted by ovariectomy (from 0.30 to 0.14 mumol.min-1.g kidney wt-1.mm Hg-1, P < .05), and that of DR rats was not. The ovariectomized DS rats developed hypertension earlier than sham-operated DS rats by salt loading. These results show that ovariectomy enhances genetic salt sensitivity by blunting the pressure-natriuresis relationship, which precedes the development of overt hypertension in female DS rats.
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Otsuka et al. (1996) studied Salt sensitivity and hypertension (preclinical animal model). Ovariectomy vs. Sham operation / intact ovaries was evaluated on Pressure-natriuresis relationship slope (mumol/min/g kidney wt/mm Hg) in Dahl-Iwai salt-sensitive rats (p=<0.05). Ovariectomy further blunted the pressure-natriuresis slope in Dahl-Iwai salt-sensitive rats from 0.30 to 0.14 mumol/min/g kidney wt/mm Hg (P<0.05), accelerating salt-induced hypertension.
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