Objective: To test the hypothesis that heavy smoking may interfere with the variation in ambulatory blood pressure (ABP) and sympathetic nervous system in essential hypertension.
Methods: We compared the office and 24-hour ABP of 48 untreated hypertensive smokers (> 20 cigarettes daily) with 90 non-smoking hypertensives matched for age, sex and body mass index. ABP was recorded using fully automatic SpaceLabs 90,207 units set to take a measurement every 15 minutes during the day (7.00 a.m.-10.00 p.m.) and every 20 minutes during the night (10.00 p.m.-7.00 a.m.). Urine collection for urinary sodium, potassium, epinephrine and norepinephrine excretion was performed during the 24-hour period of ABP monitoring. Catecholamines were measured by high pressure liquid chromatography.
Results: The office blood pressure readings of the smoking and non-smoking groups were 156.7/103.4 and 156.5/103.9 mmHg respectively. During the day-time period, ambulatory systolic and diastolic blood pressure was significantly higher in the smokers (146 +/- 12 vs 140.4 +/- 13 mmHg, p < 0.02; 96.4 +/- 8.15 vs 93.1 +/- 10 mmHg, p < 0.05 respectively). This difference was greater among patients under the age of 50 (145.9 +/- 13 vs 136.6 +/- 11 mmHg, p < 0.001 and 97.1 +/- 8.7 vs 92.3 +/- 9.9 mmHg, p < 0.02). Blood pressure during the night-time period did not differ between the two groups (130.5/81.3 vs 126.3/79.5). No differences were detected among the groups as far as urinary catecholamine excretion is concerned.
Conclusion: Our data suggest that among hypertensive subjects, smokers maintain a higher day-time ambulatory systolic and diastolic blood pressure than non-smokers, particularly in the younger patients, even though casual blood pressure is similar.