Relationship between waking–sleep blood pressure and catecholamine changes in African–American and European–American women

Abstract

Background A blunted decline in waking to sleep blood pressure (BP) is more common in African–American (AA) than European–American (EA) women. The causes of reduced BP ‘dipping’ in AA women are not known, although several factors including ethnic differences in catecholamine sensitivity have been suggested. The purpose of this study was to investigate the possible contribution of catecholamine influences on BP to ethnic differences in BP dipping in a sample of working women. Participants and methods Healthy female participants wore ambulatory BP monitors over the course of 1 work day and night. Urine samples for assay of epinephrine and norepinephrine were collected at work (approximately 11.00–15.00 h), home (approximately 06.00–22.00 h) and during sleep (approximately 22.00–06.00 h). Analysis of covariance was used to assess the relationships between changes in BP and the catecholamines by ethnicity. Results AA women (n=51; age=38.9±8.5 years) had smaller proportional BP changes from work to sleep and home to sleep than EA women (n=110; age=37.1±9.2 years). Overall, the work to sleep change in epinephrine excretion was positively associated with changes in both SBP (PP<0.001); however, there was an ethnic difference in the epinephrine–BP relationship. For AA women, these associations were highly positive and significant, but for EA women, there was little correlation. Nonetheless, the analysis also revealed that overall, the work to sleep BP changes were not directly related to ethnic differences in catecholamine variation. Conclusion The AA–EA difference in waking–sleep BP changes (dipping) is not directly related to ethnic differences in catecholamine variation; however, AA seem to have a greater BP sensitivity to epinephrine.