Older age is associated with elevated large elastic artery stiffness, a strong predictor of cardiovascular (CVD) risk in middle-age/older (MA/O) adults independent of blood pressure (BP). Greater 24-hour systolic BP variability (BPV) is also an independent risk factor for CVD and is linked to large artery stiffness in MA/O adults with hypertension and diabetes. However, its relation to age-related arterial stiffness in adults with low risk factor burden is unclear. We hypothesized that higher systolic BPV would be: 1) associated with advancing age, and 2) related to elevated aortic and carotid artery stiffness among healthy MA/O adults. To determine this, 98 healthy adults (ages 19-70 yrs) with measurements of systolic BPV (standard deviation of 24 hr systolic BP) via ambulatory BP monitoring, aortic stiffness (carotid-femoral pulse wave velocity, cfPWV), carotid artery stiffness (β-stiffness via carotid tonometry/B mode ultrasound) and circulating metabolic factors were included. In the entire cohort, greater systolic BPV was not associated with age, cfPWV, carotid β stiffness or circulating lipids/glucose (all P>0.05), but was correlated (age-adjusted) with 24 hr systolic BP (r= 0.41, P<0.001) and BMI (r= 0.21, P<0.05). In stepwise linear regression analyses that included age, sex, BMI, only 24 hr systolic BP was associated with systolic BPV (β= 0.14 ± 0.03, Model R
2
= 0.20, P< 0.001). Interestingly, there was no difference in 24 hr systolic BPV (11.4 ± 0.4 vs 11.4 ± 0.5 SD mmHg, P=0.99) in young (n=55; 29.0 ± 0.7 yrs) vs. MA/O (n= 43; 53.0 ± 1.2 yrs) adults despite higher cfPWV (594 ± 12 vs 913 ± 39 cm/sec, P<0.001), carotid β-stiffness (6.8 ± 0.6 vs 9.3 ±0.9 U, P=0.001) and 24 hr systolic BP (121 ± 1 vs 125 ± 2 mmHg, P<0.05). Systolic BPV was associated with BMI (r= 0.42, p< 0.01) and fasting blood glucose (r= 0.54, P= 0.001) in MA/O but not young adults. In a stepwise linear regression model among MA/O, 24 hr systolic BP (β= 0.18 ± 0.04, R
2
= 0.36, P<0.001) and fasting glucose (β= 0.10 ± 0.05, R
2
change= 0.07, P<0.001) were the only significant correlates of systolic BPV (Model R
2
= 0.43, P<0.001). In conclusion, 24 hr systolic BP and fasting blood glucose, but not age or large elastic artery stiffness, were the strongest determinants of higher systolic BPV in normotensive MA/O adults.
Cerebral and skeletal muscle feed artery vasoconstrictor responses in a mouse model with greater large elastic artery stiffness
