Pathophysiology of Hypertension in Blacks

Overall, American blacks have twice the rate of high blood pressure of American whites and five to seven times the rate of severe hypertension. As a result, American blacks have a higher incidence of stroke (50%), heart disease (30%), and kidney disease (50%). Not only are blacks more likely to develop hypertension, but the disorder develops earlier, is often more severe, and is more likely to be fatal at an earlier age. While lack of early and aggressive treatment contributes to the problem, research has shown that physiological and environmental factors play an important role. Pathophysiology of Hypertension in Blacks examines much of the research that has been done to explain the pathogenesis of hypertension among black Americans. The book is divided into four sections. The first section considers genetic mechanisms of the disease. Increased sensitivity to salt, a common feature among both normotensive and hypertensive blacks, may have developed during the slave trade and slavery as a physiological adaptation to prevent death from excessive loss of salt and water; survival favored those most able to conserve salt, an ability which predisposes black Americans today to hypertension. During childhood, this enhanced salt-sensitivity may be complicated by insulin resistance and hyperinsulinemia. The second section examines the role of social, cultural, psychosocial, and socioeconomic factors in the pathogenesis of hypertension. The authors of these chapters present models and explanations that show how these factors may influence physiological variables. The third area of the book deals with the role of urbanization and salt (both in and out of Africa), the role of diet, the role of intracellular ion metabolism, and the increasing significance of renin. The last section of the book summarizes the evidence presented in earlier chapters, and also outlines therapeutic strategies that are effective in controlling blood pressure in hypertensive blacks. The book presents underlying physiological mechanisms which may become impaired and therefore sets the stage for the application of modern molecular biology to the pathophysiology of hypertension in blacks. This book is a volume in the Clinical Physiology Series of the American Physiological Society and is based on a symposium sponsored by the Society at the 1990 meeting of the Federation of American Societies for Experimental Biology. It will be valuable to both researchers and clinicians who study and treat hypertension in blacks.