Potential Roles of Plasminogen Activator System in Coronary Vascular Remodeling Induced by Long-term Nitric Oxide Synthase Inhibition

K. Kaikita, J. A. Schoenhard, C. A. Painter, R. T. Ripley, N. J. Brown, A. B. Fogo and D. E. Vaughan. Potential Roles of Plasminogen Activator System in Coronary Vascular Remodeling Induced by Long-term Nitric Oxide Synthase Inhibition. Journal of Molecular and Cellular Cardiology (2002) 34, 617–627. Recent studies have indicated that a number of factors contribute to the pathophysiology in response to nitric oxide synthase (NOS) inhibition. We previously demonstrated that plasminogen activator inhibitor-1 deficient (PAI-1−/−) mice are protected against hypertension and perivascular fibrosis induced by relatively short-term NOS inhibition. In this study, we compared the temporal changes in systolic blood pressure and coronary perivascular fibrosis induced by long-term treatment withNω -nitro-L -arginine methyl ester (L -NAME) in wild type (WT), PAI-1−/− and tissue-type plasminogen activator deficient (t-PA−/−) mice. After initiating -NAME, systolic blood pressure increased in all groups at 2 weeks. Over a 16 week study period, systolic blood pressure increased to 143±3 mmHg (mean±SEM) in WT animals, 139±2 in t-PA−/− mice vs 129±2 in PAI-1−/− mice (P < 0.01). Coronary perivascular fibrosis increased in -NAME-treated WT and t-PA−/− mice compared to each control group (P<0.01 in WT, P<0.05 in t-PA−/−), while PAI-1−/− mice were protected against fibrosis induced by L-NAME. t-PA deficiency did not accentuate the vascular pathology or the changes in blood pressure. In situ zymography demonstrated augmented gelatinolytic activity in PAI-1−/− mice at baseline, suggesting that PAI-1 deficiency prevents the increase of collagen deposition by promoting matrix degradation. Plasma TGF-β1 levels increased in L-NAME-treated WT and PAI-1−/− mice (P < 0.01), but not in -NAME-treated t-PA−/− mice. These findings support the hypothesis that the plasminogen activator system protects against the structural vascular changes induced by long-term NOS inhibition. While PAI-1 deficiency protects against L-NAME-induced hypertension and perivascular fibrosis, t-PA deficiency does not exacerbate the vascular pathology or hypertension.