Environmental and genetic factors of hypertension in a biracial Beduin population.

This study attempts to understand the various factors involved in the pathophysiology of hypertension in black Beduins. Parameters known to differentiate US black from white hypertensives were examined. Sixty Beduin families (thirty families each of black and white, total of 205 subjects) were evaluated for environmental risk factors: a traditional nomad shepherd life-style compared with working in a city, living in tents or in western style housing and dietary habits related to cardiovascular risk factors. Blood pressure, body mass index (BMI), sodium-lithium counter transport rate and 24 hour urinary sodium excretion (UNa) were measured and the data obtained were compared between normotensives and hypertensives, within each racial group. The mean value of the BMI of the white population was greater than that of the black population while the BMI of hypertensives was greater than that of the normotensives in each of the racial groups. The mean systolic BP of black hypertensives was greater than that of the corresponding whites. There were no significant differences in UNa between the four groups. Sodium-lithium countertransport was significantly higher in the hypertensive whites compared with the normotensive population (0.46 versus 0.22 mmol Li efflux/IRBC/hr). The countertransport rate for black hypertensives was lower than that of white hypertensives (0.20 versus 0.46). Black families had lower socio-economic scores than did white families and families with a hypertensive member scored lower than did families with a normotensive history. These results demonstrate some similarities between the American and Beduin black hypertensive populations, in spite of entirely different life-styles, indicating that in these populations genetic factors, rather than environmental influences, appear to be dominant in the pathophysiology of hypertension.