Acute Effects of Electronic and Tobacco Cigarette Smoking on Sympathetic Nerve Activity and Blood Pressure in Humans

Abstract

Acute tobacco cigarette (TC) smoking increases blood pressure and sympathetic nerve activity, whereas there are scarce data on the impact of electronic cigarette (EC) smoking. We assessed the acute effects of TC, EC and sham smoking on blood pressure, heart rate and sympathetic nervous system. Methods: We studied 12 normotensive male habitual smokers (mean age 33 years) free of cardiovascular disease. The study design was randomized and sham controlled with three experimental sessions (sham smoking, TC smoking and EC smoking). After baseline measurements at rest, the subjects were then asked to smoke (puffing habits left uncontrolled) two TC cigarettes containing 1.1 mg nicotine, EC smoking or simulated smoking with a drinking straw with a filter (sham smoking), in line with previous methodology. Results: EC smoking at 5 and 30 min compared to baseline was accompanied by the augmentation of mean arterial pressure (MAP) and heart rate (p < 0.001 for all). The muscle sympathetic nerve activity (MSNA) decrease was significant during both TC and EC sessions (p < 0.001 for both comparisons) and was similar between them (−25.1% ± 9.8% vs. −34.4% ± 8.3%, respectively, p = 0.018). Both MSNA decreases were significantly higher (p < 0.001 for both comparisons) than that elicited by sham smoking (−4.4% ± 4.8%). Skin sympathetic nerve activity increase was significant in both TC and EC groups (p < 0.001 for both comparisons) and similar between them (73.4% ± 17.9% and 71.9% ± 7%, respectively, p = 0.829). Conclusions: The unfavorable responses of sympathetic and arterial pressure to EC smoking are similar to those elicited by TC in healthy habitual smokers.

Keywords: blood pressure; electronic cigarette; heart rate; sympathetic nervous system; tobacco cigarette.

Figure 1

The study design illustrating the randomization to TC, EC and sham smoking sessions in random order, each session on a separate day. EC, electronic cigarette; MSNA, muscle sympathetic nerve activity; SSNA, skin sympathetic nerve activity; TC, tobacco cigarette.

Figure 2

MAP at baseline and phases 1 and 2 of TC, EC and sham smoking. EC, electronic cigarette; MAP, mean arterial pressure; TC, tobacco cigarette, SS, sham smoking.

Figure 3

MSNA at baseline and phases 1 and 2 of TC, EC and sham smoking. EC, electronic cigarette; MSNA, muscle sympathetic nerve activity; TC, tobacco cigarette, SS, sham smoking.

Figure 4

SSNA at baseline and phases 1 and 2 EC and sham smoking. EC, electronic cigarette; SSNA, skin sympathetic nerve activity; TC, tobacco cigarette, SS, sham smoking.

Figure 5

Changes in MSNA and SSNA by TC, EC and sham smoking. EC, electronic cigarette; MSNA, muscle sympathetic nerve activity; SSNA, skin sympathetic nerve activity; TC, tobacco cigarette, SS, sham smoking.

Figure 6

EC smoking, similar to TC smoking, may act at a central level to cause a uniform increase in sympathetic nerve traffic to blood vessels, skin and the heart. Alterations in sympathetic drive are paralleled by an increase in blood pressure and heart rate, reflecting a systemic hemodynamic response to smoking of both types of cigarettes. These unfavorable effects of ECs mimicking those by TCs may chronically lead to increased risk of cardiovascular events. BP, blood pressure; CV, cardiovascular; EC, electronic cigarette; HR, heart rate; TC, tobacco cigarette.