SYMPATHETIC AND VASCULAR EFFECTS OF SHORT-TERM PASSIVE SMOKE EXPOSUREIN HEALTHY NONSMOKERS

Background The physiological effects of cigarette smoking have been wi dely studied; however, little is known about the effects of acute expo sure to sidestream smoke (passive smoking). We examined the effects of sidestream smoke on muscle sympathetic nerve activity (MSNA) and fore arm vascular resistance (FVR) at rest and during stressful stimuli, in cluding the sold presser test (CPT), sustained handgrip (SHG). and men tal stress (MS). Methods and Results In 17 healthy nonsmokers, blood p ressure (BP). heart rate (HR). forearm blood flow (venous occlusion pl ethysmography), FVR, and MSNA (obtained through direct intraneural rec ordings) were measured before and during inhalation of sidestream smok e in one session (n=16) and before and Juring vehicle (air) inhalation in another session (n=17) on a separate day. The order of sessions wa s randomized between subjects. Responses to CPT, SHG, and MS were meas ured before and after inhalation of smoke or vehicle tie, twice during each session). After 15 minutes' exposure to sidestream smoke, plasma nicotine and carboxyhemoglobin levels increased to 0.77+/-0.11 ng/mL and 0.36 +/- 0.04% (mean +/- SEM, P<.05), respectively, Sidestream smo ke, but not vehicle inhalation, increased resting MSNA from 23 +/- 2 t o 28 +/- 2 bursts/min (P<.05). FVR increased xith passive smoking, but this increase was not significantly different from the change in FVR with vehicle. plasma norepinephrine and epinephrine, BP, and HR were n ot changed significantly by sidestream smoke. The responses of MSNA, B P, HR, and FVR to the stressful stimuli were net potentiated by sidest ream smoke. except for an increased BP response to the CPT (P<0.5). Co nclusions Acute short-term passive (sidestream) smoke exposure elicits a modest increase in MSNA in healthy nonsmokers but does not change H R, BP, or FVR.