Shear stress acting on endothelial cells produces vasodilation. This is arguably the most important physiological endothelial mechanism of dilation and occurs in virtually every vascular bed. Our recent data indicate that flow-mediated dilation (FMD) occurs in coronary arterioles from patients with coronary disease but operates through a novel mechanism involving endothelial production of reactive oxygen species (ROS) including hydrogen peroxide (H2O2). Surprisingly the mitochondrial respiratory chain plays a necessary role in FMD in the human heart. The overall goal of this application is to examine the FMD signaling sequence from endothelium to smooth muscle studying 3 aims. 1) We will examine the mechanism of endothelial production H2O2. using fresh human coronary arterioles from subjects with coronary disease and cultured human endothelial cells from both microvascular tissue and conduit arteries for comparison. We shall pursue exciting preliminary data that indicate both mitochondria and NADPH oxidase are involved, possibly through a ROS- induced ROS release mechanism and activation of Rac1. 2) Using a novel bioassay technique to assess vasodilation and smooth muscle potassium channel opening, we shall identify the endothelial derived hyperpolarizing factor (EDHF) responsible for dilation. Both arachidonic acid metabolites and H2O2 are necessary for FMD, but preliminary studies point to H2O2 as the transferable dilator agent. 3) We shall determine the mechanism of H2O2 -induced dilation, examining the novel hypothesis that H2O2 directly acts on PKG1? by cysteine oxidation, yielding an activated disulfide dimeric form of the enzyme. These goals span a broad, clinically relevant redox signaling pathway from endothelial H2O2 formation, to H2O2 release as a transferable vasomotor substance, to its mechanism of action on underlying smooth muscle cells. Collectively these aims address a novel mechanism of endothelium-dependent dilation involving mitochondrial generation of ROS, thus far reported only in human hearts. Results should identify new links among cellular mechanotransduction, respiration, and redox signaling that regulate important physiological events such as arteriolar vasodilation, responsible for tissue perfusion. The direct relevance to humans with chronic coronary disease provides a strong foundation for this mechanistic approach to understanding microvascular reactivity.

Public Health Relevance

Dilation resulting from shear stress acting on endothelial cells is arguably the most important physiological endothelial mechanism of dilation, and occurs in virtually every vascular bed. Although examined extensively in animals, we examine blood vessels directly from humans with heart disease to clarify the mechanisms involved. Our findings show a unique mechanism of dilation involving mitochondrial generation of ROS, thus far reported only in human hearts. Results of this proposal should identify new links among cellular mechanotransduction, respiration, and redox signaling that regulate important physiological events such as arteriolar vasodilation, responsible for tissue perfusion. The direct relevance to humans with chronic coronary disease provides a strong foundation for this mechanistic approach to understanding microvascular reactivity.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL094971-04
Application #
8208170
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Maric-Bilkan, Christine
Project Start
2009-01-01
Project End
2013-12-31
Budget Start
2012-01-01
Budget End
2013-12-31
Support Year
4
Fiscal Year
2012
Total Cost
$376,200
Indirect Cost
$128,700
Name
Medical College of Wisconsin
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
937639060
City
Milwaukee
State
WI
Country
United States
Zip Code
53226
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Durand, Matthew J; Gutterman, David D (2013) Diversity in mechanisms of endothelium-dependent vasodilation in health and disease. Microcirculation 20:239-47
Zhang, David X; Borbouse, Lena; Gebremedhin, Debebe et al. (2012) H2O2-induced dilation in human coronary arterioles: role of protein kinase G dimerization and large-conductance Ca2+-activated K+ channel activation. Circ Res 110:471-80
Dharmashankar, Kodlipet; Welsh, Aimee; Wang, Jingli et al. (2012) Nitric oxide synthase-dependent vasodilation of human subcutaneous arterioles correlates with noninvasive measurements of endothelial function. Am J Hypertens 25:528-34
Bubolz, Aaron H; Mendoza, Suelhem A; Zheng, Xiaodong et al. (2012) Activation of endothelial TRPV4 channels mediates flow-induced dilation in human coronary arterioles: role of Ca2+ entry and mitochondrial ROS signaling. Am J Physiol Heart Circ Physiol 302:H634-42
Beyer, Andreas M; Gutterman, David D (2012) Regulation of the human coronary microcirculation. J Mol Cell Cardiol 52:814-21
Zhang, David X; Gutterman, David D (2011) Transient receptor potential channel activation and endothelium-dependent dilation in the systemic circulation. J Cardiovasc Pharmacol 57:133-9
Zinkevich, Natalya S; Gutterman, David D (2011) ROS-induced ROS release in vascular biology: redox-redox signaling. Am J Physiol Heart Circ Physiol 301:H647-53
Liu, Yanping; Bubolz, Aaron H; Mendoza, Suelhem et al. (2011) H2O2 is the transferrable factor mediating flow-induced dilation in human coronary arterioles. Circ Res 108:566-73
Widlansky, Michael E; Gutterman, David D (2011) Regulation of endothelial function by mitochondrial reactive oxygen species. Antioxid Redox Signal 15:1517-30

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