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Adenosine is known to play an important role in the regulation of coronary blood flow during metabolic stress. However, there is sparse information on the mechanism of adenosine-induced dilation at the microcirculatory levels. In the present study, we examined the role of endothelial nitric oxide (NO), G proteins, cyclic nucleotides, and potassium channels(More)
PURPOSE Lactate, a key metabolite in the retinal tissue, has been implicated in regulating retinal blood flow to match retinal metabolic demand. However, the direct effect of lactate on retinal vascular tone and the possible underlying signaling mechanisms remain unknown. In the present study, the roles of endothelium-derived vasodilators, guanylyl cyclase,(More)
OBJECTIVE Elevated levels of C-reactive protein (CRP), a proinflammatory marker, are associated with reduced systemic endothelium-dependent NO-mediated dilation in patients with coronary artery disease; however, the direct effect of CRP on coronary microvascular reactivity remains unknown. Herein, we examined whether CRP can modulate endothelium-dependent(More)
Arginase shares a common substrate, L-arginine, with nitric oxide (NO) synthase (NOS). It is thought that arginase, if it is expressed in the endothelium, might play a pivotal role in the regulation of NO-mediated vasodilation by reducing the L-arginine availability to NOS. In the present study, we wanted to determine whether arginase is expressed and(More)
  • Naris Thengchaisri, Travis W Hein, +4 authors Lih Kuo
  • 2006
OBJECTIVE Overproduction of reactive oxygen species such as hydrogen peroxide (H2O2) has been implicated in various cardiovascular diseases. However, mechanism(s) underlying coronary vascular dysfunction induced by H2O2 is unclear. We studied the effect of H2O2 on dilation of coronary arterioles to endothelium-dependent and endothelium-independent agonists.(More)
Angiotensin II (Ang II) is a potent vasoconstrictor in the peripheral circulation and has been implicated in many cardiovascular diseases associated with elevated oxidative stress. However, its direct vasomotor action and its linkage to oxidative stress-induced vascular dysfunction in the coronary microcirculation remain elusive. In this study, we directly(More)
Oxidized LDLs (Ox-LDLs) inhibit endothelium-dependent dilation of isolated conduit arteries in a manner comparable to the impairment demonstrated in atherosclerotic vessels. However, it is not known whether the microvessels, which do not develop atherosclerotic lesions, are susceptible to Ox-LDL. Since endothelial release of NO plays an important role in(More)
One characteristic of hypertension is a decreased endothelium-dependent nitric oxide (NO)-mediated vasodilation; however, the underlying mechanism is complex. In endothelial cells (ECs), L-arginine is the substrate for both NO synthase (NOS) and arginase. Because arginase has recently been shown to modulate NO-mediated dilation of coronary arterioles by(More)
PURPOSE Adenosine is a potent vasodilator of retinal microvessels and is implicated to be a major regulator of retinal blood flow during metabolic stress. However, the receptor subtypes and the underlying signaling mechanism responsible for the dilation of retinal microvessels in response to adenosine remain unclear. In the present study, the roles of(More)
PURPOSE Although the arteriolar segment contributes to flow regulation, there is sparse information at the single microvessel level on how vasomotor function is regulated in the human retina. The authors have previously reported vasoreactivity and its underlying mechanisms in isolated porcine retinal arterioles. Herein, they studied human retinal arterioles(More)