Blood Pressure Responses to Muscle Sympathetic Nerve Activity are Accentuated in Smokers

Abstract

Smoking is a risk factor for hypertension and other cardiovascular diseases. It is unclear if the blood pressure (BP) response to sympathetic activity is altered in smokers. In this project, we examined the BP response to muscle sympathetic nerve activity (MSNA) in 18 smokers and 10 nonsmokers. BP (Finapres), heart rate, and MSNA (microneurography) were continuously recorded during 10 min of supine rest, and these variables were analyzed on a beat-by-by basis. Signal averaging was used to examine the responses in the mean arterial pressure (MAP) and heart rate for 15 sec according to the onset of the MSNA bursts. MAP in smokers was higher than that in nonsmokers (92.5±2.3 vs. 85.6±2.9 mmHg, P=0.02). MSNA in smokers was not significantly greater than that in nonsmokers (24.1±3.1 vs. 19.3±3.8 bursts/min, P>0.05). In the both groups, the averaged MSNA burst occurred in a nadir of the averaged MAP curve with ~1-2 sec time lag. Thereafter, MAP gradually increased, reaching a peak at ~6-8 sec following MSNA bursts. However, the MAP increase in smokers was significantly greater than that in nonsmokers (Δ2.94±0.71 vs. Δ1.58±0.31 mmHg, P<0.05). These data suggest that the BP response to the sympathetic activity may be accentuated in smokers. We speculate that altered adrenergic receptor sensitivity and/or baroreflex function may contribute to it.