Nicotine enhances the circulatory effects of adenosine in human beings.

A randomized, double-blind, and placebo-controlled study was performed in 10 healthy volunteers to evaluate a possible interaction between adenosine and nicotine in human beings. The infusion of adenosine alone (0.07 mg/kg/min) induced an increase in heart rate of 4.7 beats/min versus 0.2 beats/min after placebo administration (p less than 0.02). The infusion of adenosine alone induced a decrease in finger skin temperature compared with placebo administration (-1.0 degrees versus 0.0 degrees C, p less than 0.01). When compared with baseline values, nicotine gum chewing increased systolic and diastolic blood pressures by 6.2 and 7.0 mm Hg, respectively (p less than 0.001), heart rate by 5.5 beats/min (p less than 0.01), and plasma adrenaline levels by 0.03 nmol/L (p less than 0.025), whereas skin temperatures fell by 1.3 degrees C (p less than 0.001). The nicotine-induced increase in heart rate was larger during adenosine infusion than during placebo administration (14.9 versus 5.5 beats/min, p less than 0.001), whereas the increment of diastolic blood pressure was lower (1.1 versus 4.0 mm Hg, p less than 0.05). The increment in systolic blood pressure was not altered by concomitant adenosine infusion. The rise in plasma noradrenaline levels during the combined administration of nicotine and adenosine differed significantly from the response to nicotine alone (+ 0.23 versus -0.05 nmol/L, p less than 0.02). We concluded that, in human beings, the characteristic hemodynamic response to adenosine infusion is enhanced by nicotine.