Browsing Department of Pharmacology and Toxicology: Faculty Research and Presentations by Authors
Peroxynitrite Mediates Diabetes-Induced Endothelial Dysfunction: Possible Role of Rho Kinase ActivationEl-Remessy, Azza B.; Tawfik, Huda E.; Matragoon, Suraporn; Pillai, Bindu; Caldwell, Ruth B.; Caldwell, Robert William; Department of Pharmacology and Toxicology; Vascular Biology Center (2010-11-1)Endothelial dysfunction is characterized by reduced bioavailability of NO due to its inactivation to form peroxynitrite or reduced expression of eNOS. Here, we examine the causal role of peroxynitrite in mediating diabetes-induced endothelial dysfunction. Diabetes was induced by STZ-injection, and rats received the peroxynitrite decomposition catalyst (FeTTPs, 15â mg/Kg/day) for 4 weeks. Vasorelaxation to acetylcholine, oxidative-stress markers, RhoA activity, and eNOS expression were determined. Diabetic coronary arteries showed significant reduction in ACh-mediated maximal relaxation compared to controls. Diabetic vessels showed also significant increases in lipid-peroxides, nitrotyrosine, and active RhoA and 50% reduction in eNOS mRNA expression. Treatment of diabetic animals with FeTTPS blocked these effects. Studies in aortic endothelial cells show that high glucose or peroxynitrite increases the active RhoA kinase levels and decreases eNOS expression and NO levels, which were reversed with blocking peroxynitrite or Rho kinase. Together, peroxynitrite can suppress eNOS expression via activation of RhoA and hence cause vascular dysfunction.
The role of RhoA/Rho kinase pathway in endothelial dysfunctionYao, Lin; Romero, Maritza J.; Toque, Haroldo A.; Yang, Guang; Caldwell, Ruth B.; Caldwell, Robert William; Department of Pharmacology and Toxicology; Vascular Biology Center (2010)Endothelial dysfunction is a key event in the development of vascular disease, and it precedes clinically obvious vascular pathology. Abnormal activation of the RhoA/Rho kinase (ROCK) pathway has been found to elevate vascular tone through unbalancing the production of vasodilating and vasoconstricting substances. Inhibition of the RhoA/ROCK pathway can prevent endothelial dysfunction in a variety of pathological conditions. This review, based on recent molecular, cellular, and animal studies, focuses on the current understanding of the ROCK pathway and its roles in endothelial dysfunction.