Vascular type 1 angiotensin receptors control blood pressure by augmenting peripheral vascular resistance in female mice

Angiotensin II (ANG II) is a major mediator of hypertension pathogenesis. In addition, there are well-documented differences in expression of the renin-angiotensin system (RAS) components and ANG II responses between males and females, which may explain sex differences in blood pressure (BP) and hypertension epidemiology. We previously showed that type 1A angiotensin (AT_1A) receptors in vascular smooth muscle cells (VSMCs) play a critical role in BP regulation and hypertension pathogenesis, but these studies were carried out in male mice. Therefore, the major goal of the current studies was to examine the impact of VSMC AT_1A receptors on BP and hypertension pathogenesis in female mice. We found that elimination of VSMC AT_1A receptors in female mice reduced (≈8 mmHg) baseline BP without altering sodium sensitivity. The severity of ANG II-induced hypertension was diminished (≈33% reduction in BP), particularly during the last 2 wk of chronic ANG II infusion, compared with controls, but natriuresis was not altered during the first 5 days of ANG II infusion. Urinary norepinephrine levels were enhanced in female SMKO compared with control mice. There was a virtually complete elimination of ANG II-induced kidney hemodynamic responses with attenuation of acute vasoconstrictor responses in the systemic vasculature. These findings demonstrate that direct vascular actions of AT1A receptors play a prominent role in BP control and hypertension pathogenesis in female mice.