The Effects of Ethnic Discrimination and Socioeconomic Status on Endothelin-1 Among Blacks and Whites

Abstract

Ethnic disparities in cardiovascular disease (CVD) may partially reflect differences in chronic stress burden that vary by social class and exposure to ethnic discrimination. Stress is associated with increased endothelin-1 (ET-1). This study examined the relationship of ET-1 to socioeconomic status (SES) and to perceived ethnic discrimination among black (n = 51) and white (n = 65) adults (mean age 36.5). The Perceived Discrimination subscale of the Scale of Ethnic Experience measured exposure to discrimination and the Hollingshead Two-Factor Index of Social Position assessed SES. Plasma ET-1 was sampled upon awakening after an overnight admission. SES and ET-1 levels were similar across ethnic groups, but mean discrimination scores were higher among blacks than whites (P < 0.001). Multiple regressions found that the SES x ethnicity interaction was associated with ET-1 (P < 0.05), after adjustment for gender, resting mean arterial pressure (MAP), body mass index (BMI), and exercise frequency. Regressions stratified by ethnicity revealed that lower SES correlated with higher ET-1 in whites (P < 0.001), but not blacks, and accounted for 21% of the variance. Another series of regressions revealed an interaction effect of ethnicity by discrimination on ET-1 (P < 0.05). Increased discrimination correlated with increased ET-1 among blacks (P < 0.05), but not whites, and explained 11% of the variance after adjustment for SES, gender, exercise frequency, and socially desirable response bias. Thus, ET-1 levels increased in association with different psychosocial burdens in blacks and whites. Plasma ET-1 was higher among whites with lower SES and among blacks with higher levels of perceived ethnic discrimination, regardless of SES.