This is a randomized, double-blind, crossover study to evaluate chlorthalidone and hydrochlorothiazide and their effects on endothelial function in hypertensive patients. Subjects will receive chlorthalidone 12.5 mg, hydrochlorothiazide 25 mg, and placebo each for 4 weeks with a 1 week washout between study periods. Sequence of study drugs will be randomized. Flow mediated vasodilatation will be measured at baseline and after each treatment period.
