The broad objective of this study is to define the integrated cardiorenal response to acute volume expansion (VE) in humans with presystolic dysfunction (PSD), prediastolic dysfunction (PDD), and normal cardiac function. We hypothesized that there is an impaired cardiorenal endocrine response to acute VE in PSD and PDD which is characterized by the lack of appropriate activation of urinary cGMP and urinary sodium excretion. Further, we hypothesized that PSD, PDD, and normal control subjects would respond similarly to exogenous administration B-type natriuretic peptide (BNP).