SMOKING IMPAIRS BAROREFLEX SENSITIVITY IN HUMANS

In 10 healthy smokers, finger blood pressure was recorded continuously for 1 h in a supine control condition and for 1 h while smoking four cigarettes, one every 15 min. Smoking increased average systolic blood pressure (+19%, P < 0.01) and its variability and reduced pulse inter val (reciprocal of heart rate, -22%, P < 0.01) and its variability. Ba roreflex sensitivity, as assessed by the slope of spontaneous hyperten sion/bradycardia or hypotension/tachycardia sequences and by the alpha -coefficient (squared ratio between pulse interval and systolic blood pressure spectral powers at 0.1 Hz) was significantly decreased (P < 0 .01) during smoking, whereas there were no effects of smoking on the r eflex changes in pulse interval induced by carotid baroreceptor stimul ation through a neck suction device. Sham smoking by a drinking straw had no effects an any of the above parameters. Thus, when assessed in the absence of laboratory maneuvers in daily Life conditions, barorefl ex sensitivity is markedly impaired by smoking. This impairment may co ntribute to the smoking-induced increase in blood pressure and heart r ate as well as to the concomitant alterations in their variability.