The Mediating Role of Plasma Renin and Aldosterone Activity on Arterial Stiffness in Sedentary Adults

    ABSTRACT Jennifer J Strout1, Jeb F Struder1, Alexander Pomeroy1, Kristen M Paternoster1, Christopher E Grice1, Andrew M Koessler1, Taylor Shorter1, Craig Paterson1,2, Gaurav Dave1, Bethany B Gibbs3, Feng-Chang Lin1, Michelle L Meyer1, Maihan B Vu1, and Erik D Hanson, FACSM1 1 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA 27599 2 University of Bristol, Bristol, UK, BS8 2PS 3 West Virginia University, Morgantown, WV, USA 260506 PURPOSE: To explore the impact of practical SBI implementation on AS mitigation and mechanistic mediators' plasma renin activity (PRA) and ALD in healthy, inactive, sedentary adults. METHODS: This preliminary analysis included 39 adults (79.5% F, age: 45±8y, BMI: 27.9±5.5kg•m-2) who underwent 4 visits comprised of 4 h of uninterrupted (CON) or interrupted (standing, STAND; walking, WALK; combination, MIXED) sitting bouts. After 20 min of semi-recumbent rest, carotid-femoral pulse wave velocity (cfPWV) was collected via cuff-based oscillometry, followed by blood samples before and after each condition, with linear mixed models and mediation analyses used to assess condition-specific responses in cfPWV, PRA, and ALD (p≤0.05). RESULTS: SBI resulted in nonsignificant time-by-condition interactions for cfPWV (p=0.508; R2m: 0.008) , PRA (p=0.518; R2m: 0.086), and ALD (p=0.601; R2m: 0.051) relative to CON. PRA (β: -0.0021±0.0017ng•mL-1•hr-1, 95%CI [-0.0061-0.0006], p=0.209) nor ALD (β: -0.00104±0.00268ng•dL-1, 95%CI [-0.0060-0.0047], p=0.699) mediated the indirect SBI-cfPWV association, contributing to 72% and 37.6% of the total effect, respectively. However, both PRA (β=0.0293±0.00886ng•mL-1•hr-1, 95%CI [-0.0118-0.0469], p<0.001 and ALD (β= -0.0637±0.0122 ng•dL-1, 95%CI [0.0397-0.0892], p<0.001) predicted cfPWV. CONCLUSIONS: Biological predictability was suggested with increased PRA and ALD corresponding to cfPWV increases of 0.1m•s-1 and 0.9m•s-1, respectively; implying RAAS involvement in early AS presentation with a 1.0 m•s-1 increase in cfPWV considered clinically significant. Evidence of SBI-induced AS mitigation was not observed, potentially due to a lack of statistical power as indicated by low marginal R2. Future work should explore how AS mitigation is impacted by SBI adaptation while maintaining feasible implementation. FUNDING SOURCE: This research was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number R01HL157187.