ABSTRACT: An increased arterial stiffness (AS) has been proposed as a likely mechanism for a reduced cardiac baroreflex sensitivity (BRS) and the associated increases in 24h blood pressure (BP) variability (BPV). Aim of the present study was to explore this issue in a group of 90 normotensive, non-obese, healthy adults (mean age 48 10 yrs, 50% F). Methods: BRS was assessed by computer analysis of 10 min beat-to-beat BP and ECG recordings obtained in resting supine. The linear regression slope of spontaneous concomitant increases or decreases in systolic BP and RR interval were calculated, averaged and expressed as total slope of BRS (ms/mmHg). Simultaneous recordings of pulse waveform were obtained by means of a validated oscillometric device for ABPM (Mobil-O-Graph NG, IEM, Stolberg, Germany) with inbuilt transfer-function like method, and pulse wave velocity (PWV, m/s) calculated. BPV was assessed for systolic and diastolic BP as 24h standard deviation (SD), weighted 24h SD (wSD), daytime and night-time SD from 24h ABPM. Results: In multiple linear regression analysis AS (assessed through PWV), had the strongest effect on BRS variation (beta:-0.50, p<0.0001), followed by HR and male sex. No significant effect was observed for age or MAP on BRS (See table). A similar independent analysis, showed a significant inverse relationship between BRS and daytime systolic BP SD (beta:-0,23; pZ0.036) Conclusion: Our findings suggest that in normotensive, otherwise healthy adults, decreased BRS and, indirectly, the associated increased day time systolic BPV might be largely explained by an increased AS, independently of age and BP levels.COL0070223