Sex-Specific Modulation of Blood Pressure and the Renin-Angiotensin System by ACE (Angiotensin-Converting Enzyme) 2

We showed ACE (angiotensin-converting enzyme) 2 is higher in the kidney of male compared with female mice. To further investigate this sex difference, we examined the role of ACE2 in Ang-[1–8] (angiotensin [1–8])–induced hypertension and regulation of the renin-angiotensin system in the kidney of WT (wild type) and Ace2 KO (knockout) mice. Mean arterial pressure rose faster in WT male than WT female mice after Ang-[1–8] infusion. This sex difference was attenuated in ACE2 KO mice. Ang-[1–8] infusion reduced glomerular AT1R (angiotensin type 1 receptor) binding in WT female mice by 30%, and deletion of Ace2 abolished this effect. In contrast, Ang-[1–8] infusion increased glomerular AT1R binding in WT male mice by 1.2-fold, and this effect of Ang-[1–8] persisted in Ace2 KO male mice (1.3-fold). ACE2 also had an effect on renal protein expression of the neutral endopeptidase NEP (neprilysin), the enzyme that catabolizes Ang-[1–10] (angiotensin [1–10]), the precursor of Ang-[1–8]. Ang-[1–8] infusion downregulated NEP protein expression by 20% in WT male, whereas there was a slight increase in NEP expression in WT female mice. Deletion of Ace2 resulted in lowered NEP expression after Ang-[1-8] infusion in both sexes. These findings suggest sex-specific ACE2 regulation of the renin-angiotensin system contributes to female protection from Ang-[1–8]–induced hypertension. These findings have ramifications for the current coronavirus disease 2019 (COVID-19) pandemic, especially in hypertension since ACE2 is the SARS-CoV-2 receptor and hypertension is a major risk factor for poor outcomes.