ACUTE TOLERANCE TO THE CARDIOVASCULAR EFFECTS OF NICOTINE

Acute tolerance to cardiovascular effects of nicotine was examined by presenting to male smokers a single administration of each of three different doses of nicotine (0.5, 1.0, 2.0 mg) or a placebo (0 mg) in a brief series of nasal spray boluses to mimic nicotine intake via smoking. Each dose was presented on a separate occasion. Changes in heart rate, systolic and diastolic blood pressure, finger pulse amplitude (peripheral vasoconstriction) and, in a subsample, plasma nicotine concentration were assessed during and after dose administration. Acute tolerance to nicotine was determined by comparing responses at ascending plasma nicotine concentrations during dose administration with the responses at comparable descending plasma concentrations following administration. For each nicotine dose, there was substantial acute tolerance to blood pressure, but less tolerance to heart rate (except for 0.5 mg), and little tolerance to pulse amplitude responses. These findings indicate that cardiovascular adaptation to nicotine during cigarette smoking may be rapid but variable in magnitude depending on the response being measured.