The kidney regulates blood pressure by controlling urinary salt and water excretion. Angiotensin II (AngII), a key player in controlling blood pressure, constricts blood vessels, stimulates vasopressin and aldosterone release, stimulates thirst, and increases sodium absorption from the proximal tubule. All effects cause increased blood pressure. Sex differences in the regulation of arterial blood pressure involve events surrounding the renin‐angiotensin‐aldosterone system. Evidence generally supports a protective mechanism for females with AngII‐induced hypertension; although, conflicting evidence exists. The purpose of this study was to investigate sex differences in CD‐1 mice under AngII administration for a period of 10 days. We hypothesized that female mice would be protected from AngII‐induced increase in mean arterial pressure (MAP) compared to male mice and that the renal handling of salt and water contributes to this protection. Four‐week old CD‐1 mice were obtained from Envigo, Inc. (Indianapolis, IN). Two studies, one with females and one with males, were conducted. Mice were placed in metabolic cages and consumed normal diet and water, ad libitum, for 15 days. After the first 5 days, an Alzet™ minipump containing either AngII (n=5) or vehicle (n=5) was implanted subcutaneously in each mouse to ensure continuous AngII infusion (1 mg/kg/min). Daily measurements included MAP via the tail‐cuff method (Kent Scientific, CODA System), urinary output, and urinary sodium excretion. MAP (mmHg) was not different between females and males in the 5‐day control period (85.1 ± 3.7 vs 81.7 ± 4.0, respectively). AngII‐treatment increased MAP in both females and males (110.3 ± 4.4 and 105.8 ± 3.0, p<0.001, compared to respective control period). Interestingly, AngII‐treated females showed higher urine output than AngII‐treated males (9.7 ± 0.8 vs 7.4 ± 0.4 ml/day, p<0.05) and also had higher sodium excretion (242 mEq/day vs 166 mEq/day, p<0.01). Absolute food intake in females and males was not different, however, females consumed more food per body weight. We conclude that female mice are not protected from AngII‐induced increase in MAP compared to male mice for a 10‐day AngII infusion period. However, based on the sodium excretion data, protection may be observed later from increased urine and sodium output in females. Results suggest that the renal handling of salt and water could be an important determinant of sex differences in blood pressure regulation.Support or Funding InformationNational Institute of General Medical Sciences of National Institutes of Health through Grant Number 8P20GM103447This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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