Ethnicity, social class and hostility: effects on in vivo beta-adrenergic receptor responsiveness

Little is known about the potential influences of social and psychosocial variables in accounting for ethnic differences in the beta-adrenergic receptor. We examined the effects of ethnicity, social class, and other variables on an in vivo marker of beta-adrenergic receptor responsiveness (Chronotropic 25 Dose, CD(25)) for 224 African-Americans and Caucasian-Americans. Social class was determined using the clinician-rated Hollingshead two-factor index. The Cook-Medley hostility and Buss-Durkee assaultiveness subscales were administered to a subset of subjects. Results indicated that African-Americans had decreased beta-receptor responsiveness compared to Caucasian-Americans after controlling for social class, age, and smoking (P=0.001). Secondary analysis for a subset of subjects revealed significant hostility x ethnicity interactions, such that hostility predicted decreased beta-receptor responsiveness for Caucasian-Americans (P=0.004), but not for African-Americans. Thus, decreased beta-adrenergic receptor responsiveness in African-Americans does not appear to be due to differences in current social class, age, or smoking status, nor to higher reports of hostility.