Subtle Renal Injury Is Likely a Common Mechanism for Salt-Sensitive Essential Hypertension

Despite the fact that essential hypertension was originallydescribed as hypertension occurring in the absence of clinical renal disease,1 Dahl et al later showed by transplan-tation studies in experimental models of hypertension that the kidney is ultimately responsible for the elevation in blood pressure,2 a finding that was verified later in humans.3 Most authorities believe that the mechanism by which the kidney causes hypertension involves a physiological defect in so-dium excretion as championed by Guyton et al.4 Support for this mechanism is extensive and includes both epidemiolog-ical5 and physiological6 studies. Several hypotheses have been proposed to explain the mechanism responsible for the defect in renal sodium handling. A favored hypothesis is that hypertension results from a polygenic defect in which there are alterations in the regulation or expression in tubular transport systems