Introduction
Primary aldosteronism (PA) is a common cause of secondary hypertension and is characterized by excessive production of aldosterone despite lower renin activity (1). Mutations in the chloride channel 2 (Clcn2) gene cause Familial Primary Aldosteronism Type II (FH-II), which is a milder form of hyperaldosteronism associated with high blood pressure (BP) (2). However, the mechanisms behind the association of high levels of aldosterone and the elevation in BP are poorly understood. Volume regulation by the kidney and vascular function are well established regulators of BP (3). Thus, in this study we aimed to examine BP, renal function, and vessel compliance in a novel mouse model of FH-II due to a R180Q Clcn2 mutation.

Methods
The mouse model with a R180Q Clcn2 mutation was generated using CRISPR/Cas9 gene editing. Young and aged male wildtype (WT), heterozygote (Hz) and homozygote mutant (Mut) mice were characterized for BP, vessel compliance (wire myography), and kidney function (metabolic cage studies). BP in 8-11-week-old mice (WT, n=5; Mut, n=5; Hz, n=5) were measured via tail cuff plethysmography, whereas BP in older 16-20-week-old mice (WT, n=3; Mut, n=3; Hz, n=5) were measured via gold standard radio-telemetry. 24-hour urine samples were collected via metabolic cage studies, and blood samples were collected via submandibular vein for plasma. Mesentery arteries were collected from a separate cohort of similarly aged mice and vessel compliance studies were performed ex vivo using wire myography. Data are presented as mean ± standard error mean (SEM) and were analyzed using 2-way ANOVA with Tukey’s multiple comparisons test. P-value of ≤0.05 is considered statistically significant.

Results
In the older cohort of animals, systolic BP was found to be significantly higher in the Mut and Hz groups compared to their age-matched WT controls (P<0.05). Furthermore, this increase in BP was associated with a decrease in vessel compliance (P<0.05). However, in the younger animals, there was no significant difference in BP and/or vessel compliance between the genotypes, suggesting that there could be a time-dependent increase in BP due to increase in aldosterone, which could be a potential driving factor for the development of disease in this model. The urine and plasma analyses for this study are still to be determined.

Conclusion
We have shown that BP increases with age in the Mut in our model of hyperaldosteronism, and that this elevation in BP with age is associated with reductions in vessel compliance. This suggests that the increase in aldosterone levels could be a potential driving factor behind the development of higher blood pressure with age in this model. Further studies are still required to determine whether the development of disease in this model is also associated with any changes in renal function. This would help to determine potential developmental origins and further our understanding of the physiological mechanisms behind the development of this disease.