SMOKING IS ASSOCIATED WITH CHRONIC SYMPATHETIC ACTIVATION IN HYPERTENSION: 9C.05

Abstract

Objective: Previous studies have shown that smoking contributes importantly to short-term modulation of sympathetic nerve traffic. However, effect of smoking status on resting muscle sympathetic nerve activity (MSNA) in hypertension is unknown. Therefore, we tested the hypothesis that smoking is associated with chronic sympathetic activation in patients with essential hypertension. Design and Methods: We measured MSNA, heart rate (HR) and blood pressure during undisturbed supine rest in 30 hypertensive smokers (22 males, age 38 ± 4 years, BMI 27 ± 1 kg/m2, mean ± SEM). These measurements were compared with those obtained in 38 non-smoking hypertensive patients matched for gender, age and BMI. All hypertensives underwent 24-hour ambulatory blood pressure monitoring. Patients were newly diagnosed, never treated for hypertension and were free of any other known diseases. Results: In comparison to non-smokers, smokers had smaller office-daytime SBP difference (6 ± 2 vs. 15 ± 3 mmHg, respectively; P < 0.01). Despite similar resting values, HR in smokers was greater than in non-smokers during both daytime (86 ± 3 vs. 77 ± 2 bpm, respectively; P < 0.001) and nighttime (73 ± 3 vs. 66 ± 2 bpm, respectively; P < 0.01). MSNA was elevated in smokers (36 ± 3 bursts/min) as compared to non-smokers (28 ± 3 bursts/min; P < 0.01). Multiple linear regression analysis revealed that only age and smoking status were linked independently to MSNA (R2 = 0.42, P < 0.001). Similar results were obtained when MSNA was expressed as bursts/100 heart beats. Conclusions: In patients with essential hypertension, smoking is independently associated with chronic increase in muscle sympathetic nerve activity. These findings may have implications for our understanding of the mechanisms linking smoking to cardiovascular events.