In normotensive volunteers who habitually smoked more than 20 cigarettes a day, 1-h beat-to-beat blood pressure recordings were taken. Measurements were made using a non-invasive finger device when the subjects were not smoking (1h, control) and during an hour in which the subjects were asked to smoke four cigarettes, one every 15 min. The first cigarette smoked produced a marked increase in systolic and diastolic blood pressures and the heart rate. The peak blood pressure and heart rate values observed for the first cigarette did not change when the remaining three cigarettes were smoked, indicating that the responses were neither attenuated nor increased by repeated smoking. However, after each cigarette, the pre-smoking values did not return to baseline, but were successively greater for the second, third and fourth cigarettes, indicating that blood pressure and the heart rate undergo a persistent increase during smoking. Compared with the hour-long non-smoking period, mean values over the smoking period were 18.8%, 14.0% and 29.7% higher for systolic and diastolic blood pressure and the heart rate, respectively. Cigarette smoking also increased the blood pressure and heart rate standard deviations around the mean, thereby increasing the variability. The effects of atenolol and doxazosin on the blood pressure and heart rate responses to smoking were investigated in two placebo-controlled, single-blind, randomly allocated, crossover studies. Compared with placebo, atenolol (50-100 mg given once a day four 4 days) significantly attenuated the smoking-induced increase in the heart rate but not the increase in systoloc or diastolic blood pressure. With doxazosin (2-4 mg for 4 days), mean systolic and diastolic blood pressures were significantly lower than with placebo during the hour-long smoking period, the pressor responses being reduced by 59.8% (systolic) and 43.9% (diastolic). During the smoking period there was no significant difference in the heart rate between doxazosin and placebo. Thus, the selective α1 inhibitor, doxazosin, attenuated the persistent increase in blood pressure induced by repeated smoking, its effects being more evident than that of atenolol.
|Journal||Journal of Hypertension|
|Issue number||SUPPL. 5|
|Publication status||Published - 1990|
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