The STRETCH Study: Distensibility on Endothelial-Dependent Vasoreactivity in Subjects With Systolic Hypertension

The primary objective of the double-blind segment is to compare effects of alagebrium vs placebo on change from baseline in endothelial function, as assessed by flow-mediated vasodilation (FMD).

The secondary objectives of the double-blind segment are to: * Compare the effects of alagebrium vs placebo on the change from baseline in endothelial-mediated vasoreactivity immediately after exercise, as assessed by pulse perfusion-mediated vasodilation (PPMV). * Confirm results observed in the single-blind segment. * Explore several variables as potential independent predictors of vascular stiffness and endothelial function. These parameters include age, body mass index, gender, renal disease, history of cardiovascular disease, serum cholesterol, and antihypertensive medication use. * Provide insight into nitric oxide-dependent endothelial function in the setting of increased arterial stiffness by determination of substances in the nitric oxide signaling pathway (specifically, levels of serum cGMP; serum nitrate and nitrite; and serum asymmetric dimethylarginine \[ADMA\], an endogenous inhibitor of nitric oxide synthase). * Provide insight into the relationship between AGE levels (AGE markers: pentosidine, furosine), collagen metabolism (collagen markers: procollagen I carboxyterminal propeptide \[PICP\], procollagen type I N terminal propeptide \[PINP\], cross-linked carboxyterminal telopeptide of Type I collagen \[ICTP\], n-terminal propeptide of type III procollagen \[PIIINP\]), and endothelial function; and insight into the changes in these markers in response to treatment with an AGE cross-link breaker (alagebrium). * Provide insight into the relationship between markers of inflammation \[specifically, free and total serum matrix metalloproteinase-1(MMP-1), free tissue inhibitor of metalloproteinase 1 (TIMP1), intercellular adhesion molecule-1 (ICAM), vascular cellular adhesion molecule (VCAM), P-selectin, von Willebrand factor (vWf), interleukin-6 (IL-6), endothelin 1, VEGF, NFkβ, TGF-β, IGF-1 and high-sensitivity C reactive protein (hs CRP)\] and endothelial function; and insight into the changes in these markers in response to treatment with an AGE cross-link breaker (alagebrium).