No abstract

The prevalence of essential hypertension is higher among blacks than whites. One reason for this difference may be that blacks are more reactive to stressors that produce vasoconstrictive responses. Two studies were conducted to test this hypothesis, one with 10- to 14-year-old males (20 whites, 20 blacks) and one with young adult males (10 whites, 10 blacks). Subjects had blood pressure, heart rate, cardiac output, and total peripheral resistance measured before, during, and after exposure to forehead cold stimulation. In both studies, blacks exhibited greater increases in diastolic blood pressure and total peripheral resistance to the stressor than whites. The findings are discussed in relation to blacks' greater pressor reactivity to stress, which appears to be mediated by changes in total peripheral resistance.

No abstract

We report a breast-fed infant with clinical evidence of rickets and with dilated cardiomyopathy who responded well to supplemental calcium and vitamin D. We believe that this is the first report of such an association in an American child.