In vivo observation of subendocardial microvessels of the beating porcine heart using a needle-probe videomicroscope with a CCD camera.

Yada, Toyotaka; Hiramatsu, Osamu; Kimura, A.; Goto, Masami; Ogasawara, Yasuo; Tsujioka, Katsuhiko; Yamamori, Shinji; Ohno, Kohei; Hosaka, Haruhiko; Kajiya, Fumihiko

doi:10.1161/01.res.72.5.939

Cited by 121 publications

(115 citation statements)

References 21 publications

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“…NO release is augmented by mechanical stimulation such as shear stress (2-6), pulsatile flow (7,8), and axial strain (9). Such mechanical stresses, which are produced by the periodic myocardial contraction and relaxation, directly influence the coronary blood vessels, acting as an overwhelmingly dominant factor of the coronary blood flow regulation (10)(11)(12). Under the stimulatory influences by the mechanical stresses, coronary endothelial cells produce NO on a beat-to-beat basis (13).…”

Section: N Itric Oxide (No) Released By Endothelial Cells Is Formed Frommentioning

confidence: 99%

Evaluation of bioavailability of nitric oxide in coronary circulation by direct measurement of plasma nitric oxide concentration

Neishi

Mochizuki²,

Miyasaka³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Although bioavailability of NO in the coronary circulation is commonly evaluated by acetylcholine (ACh)-induced vasodilation, a change in plasma NO concentration and its relation to the flow response after injection of ACh are still unknown. Thus, we directly measured the concentration of NO in the coronary sinus by using a catheter-type NO sensor for coronary sinus. An NO-sensitive sensor was located and fixed in a 4-Fr catheter with a soft tip for protection of vascular wall. After calibration with an NO-saturated pure water, the catheter-type NO sensor was located in the coronary sinus in anesthetized dogs. The coronary flow velocity (CFV) was measured with a Doppler guide wire. Intracoronary injection of ACh (0.4 and 1.0 g͞kg) increased plasma NO concentration in a dose-dependent manner (3-10 nM). Although ACh increased CFV by 95%, there was no significant difference between the two ACh doses. After ACh, the peak value of plasma NO concentration was observed significantly later than CFV. N G -methyl-L-arginine (NO synthase inhibitor) decreased basal NO concentration by 3 nM and suppressed the ACh-induced NO synthesis with no significant change in average peak velocity. We conclude that production of NO in the coronary circulation can be evaluated in the coronary sinus. Although ACh increases both CFV and NO concentration, CFV dose not reflect NO concentration in terms of magnitude and time course. Direct measurement of plasma NO concentration by the catheter-type NO sensor is useful to evaluate bioavailability of NO in the coronary circulation.nitric oxide synthase ͉ nitric oxide-selective sensor ͉ acetylcholine ͉ coronary blood flow ͉ endothelial function N itric oxide (NO) released by endothelial cells is formed from L-arginine by nitric oxide synthase (NOS) (1). NO release is augmented by mechanical stimulation such as shear stress (2-6), pulsatile flow (7, 8), and axial strain (9). Such mechanical stresses, which are produced by the periodic myocardial contraction and relaxation, directly influence the coronary blood vessels, acting as an overwhelmingly dominant factor of the coronary blood flow regulation (10-12). Under the stimulatory influences by the mechanical stresses, coronary endothelial cells produce NO on a beat-to-beat basis (13). In the coronary circulation, endothelium-derived NO plays fundamental roles in the regulation of blood flow, exerting a tonic vasodilator influence at rest and with increasing myocardial metabolism (14).However, bioavailability of NO is diminished in the subjects with a wide range of cardiac risk factors and pathologic conditions, such as aging, gender, smoking, hypertension, hypercholesterolemia, diabetes mellitus, hyperhomocystinemia, heart failure, infections, and polymorphisms of the endothelial NOS (15-23). Importantly, endothelial dysfunction, characterized by decreased bioavailability of NO, is a predictor of cardiovascular risk and outcome (24-28).Several techniques have been used to evaluate the endothelial function or bioavailability of NO (29). Coronary en...

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Section: N Itric Oxide (No) Released By Endothelial Cells Is Formed Frommentioning

confidence: 99%

Evaluation of bioavailability of nitric oxide in coronary circulation by direct measurement of plasma nitric oxide concentration

Neishi

Mochizuki²,

Miyasaka³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…Heart rate was kept constant at 100 bpm by right ventricular pacing after atrioventricular node blocking by 40% formaldehyde. 16 …”

Section: Animal Preparationmentioning

confidence: 99%

Hydrogen Peroxide, an Endogenous Endothelium-Derived Hyperpolarizing Factor, Plays an Important Role in Coronary Autoregulation In Vivo

et al. 2003

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Background-Recent studies in vitro have demonstrated that endothelium-derived hydrogen peroxide (H 2 O 2 ) is an endothelium-derived hyperpolarizing factor (EDHF) in animals and humans. The aim of this study was to evaluate our hypothesis that endothelium-derived H 2 O 2 is an EDHF in vivo and plays an important role in coronary autoregulation. Methods and Results-To test this hypothesis, we evaluated vasodilator responses of canine (nϭ41) subepicardial small coronary arteries (Ն100 m) and arterioles (Ͻ100 m) with an intravital microscope in response to acetylcholine and to a stepwise reduction in coronary perfusion pressure (from 100 to 30 mm Hg) before and after inhibition of NO synthesis with N G -monomethyl-L-arginine (L-NMMA). After L-NMMA, the coronary vasodilator responses were attenuated primarily in small arteries, whereas combined infusion of L-NMMA plus catalase (an enzyme that selectively dismutates H 2 O 2 into water and oxygen) or tetraethylammonium (TEA, an inhibitor of large-conductance K Ca channels) attenuated the vasodilator responses of coronary arteries of both sizes. Residual arteriolar dilation after L-NMMA plus catalase or TEA was largely attenuated by 8-sulfophenyltheophylline, an adenosine receptor inhibitor. Conclusions-These results suggest that H 2 O 2 is an endogenous EDHF in vivo and plays an important role in coronary autoregulation in cooperation with NO and adenosine.

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“…7 Compressive effects of ventricular contraction narrow intramural arteries and other vessels, displacing a significant fraction of their contained blood and greatly increasing systolic inflow resistance. 8 A finite period in early diastole is required for reexpansion and refilling of these vessels, thereby also delaying early diastolic microcirculatory perfusion. Finally, inner wall flow can be further limited if intraventricular diastolic pressure is elevated.…”

Section: Lee Et Al Mri Vs Radionuclide Perfusion Imagingmentioning

confidence: 99%

Magnetic Resonance Versus Radionuclide Pharmacological Stress Perfusion Imaging for Flow-Limiting Stenoses of Varying Severity

et al. 2004

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Background-Although magnetic resonance first-pass imaging (MRFP) has potential advantages in pharmacological stress perfusion imaging, direct comparisons of current MRFP and established radionuclide techniques are not available. Methods and Results-Graded regional differences in coronary flow were produced during global coronary vasodilation in chronically instrumented dogs by partially occluding the left circumflex artery. Regional differences in full-thickness flow quantified using microspheres were compared with regional differences obtained with MRFP and radionuclide SPECT imaging ( 99m Tc-sestamibi and 201 Tl). Relative regional flows (RRFs) derived from the initial areas under MRFP signal intensity-time curves were linearly related to reference microsphere RRFs over the full range of vasodilation (yϭ0.93xϩ4.3; r 2 ϭ0.77). Relationships between 99m Tc-sestamibi and 201 Tl RRFs and microsphere RRFs were curvilinear, plateauing as flows increased. The high spatial resolution of the MRI enabled transmural flow to be evaluated in 3 to 5 layers across the myocardial wall. Reductions in subendocardial flow were visually apparent in MRFP images for Ն50% reductions in full-thickness flow. Endocardial-to-epicardial gradients in MRFP flow increased progressively with stenosis severity, whereas transmural flow patterns in remote normally perfused myocardium remained normal. Flow reductions of Ն50% not identified by radionuclide imaging were apparent in MRFP full-thickness and transmural analyses.

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In vivo observation of subendocardial microvessels of the beating porcine heart using a needle-probe videomicroscope with a CCD camera.

Cited by 121 publications

References 21 publications

Evaluation of bioavailability of nitric oxide in coronary circulation by direct measurement of plasma nitric oxide concentration

Evaluation of bioavailability of nitric oxide in coronary circulation by direct measurement of plasma nitric oxide concentration

Hydrogen Peroxide, an Endogenous Endothelium-Derived Hyperpolarizing Factor, Plays an Important Role in Coronary Autoregulation In Vivo

Magnetic Resonance Versus Radionuclide Pharmacological Stress Perfusion Imaging for Flow-Limiting Stenoses of Varying Severity

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