Congestive heart failure (CHF) is characterized by increased vascular tone and an impairment in nitric-oxide-mediated vasodilatation. We have demonstrated that the blunted response to nitric oxide is due, in part, to a reduction in the leucine-zipper-positive isoform of the myosin-targeting subunit (MYPT1) of myosin light-chain phosphatase. Additionally, we have shown that angiotensin-converting enzyme inhibition, but not afterload reduction with prazosin, preserves leucine-zipper-positive MYPT1 isoform expression in vascular smooth muscle cells and normalizes the sensitivity to cGMP-mediated vasodilatation. We therefore hypothesized that in CHF, growth regulators and cytokines downstream of the angiotensin II receptor are involved in modulating gene expression in vascular tissue. Rats were divided into control and captopril-treated groups following left coronary artery ligation. Gene expression profiles in the aorta and portal vein at baseline and 2 and 4 weeks after myocardial infarction (MI) were analyzed using microarray technology and quantitative real-time PCR. After MI, microarray analysis revealed differential mRNA expression of 21 genes in the aorta of captopril-treated rats 2 and 4 weeks after surgery when compared to gene expression profiles at baseline and without captopril therapy. Real-time PCR demonstrated that captopril suppressed the expression of protein kinases in the angiotensin-II-mediated mitogen-activated protein kinase signaling pathway, including Taok1 and Raf1. These data suggest that in CHF, captopril therapy modulates gene expression in vascular smooth muscle, and some of the beneficial effects of ACE inhibition may be due to differential gene expression in the vasculature.