Methodological Validity and Feasibility of the Nitric Oxide Clamp Technique for Nitric Oxide Research in Human Resistant Vessels

Ueda, Shinichiro; Wada, Atsushi; Umemura, Satoshi

doi:10.1291/hypres.27.351

Cited by 9 publications

(7 citation statements)

References 31 publications

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“…Because changes in FVR alone do not stimulate t-PA release (Brown et al, 1999), the systemic effect of ISDN and sildenafil would not confound the primary outcome. An alternative approach would have been to use the NO "clamp" as described previously (Ueda et al, 2004). Although this approach may be more elegant, the use of oral ISDN and sildenafil is more applicable to the clinical situation.…”

Section: Discussionmentioning

confidence: 99%

Endogenous Nitric Oxide Contributes to Bradykinin-Stimulated Glucose Uptake but Attenuates Vascular Tissue-Type Plasminogen Activator Release

Pretorius

Brown²

2009

J Pharmacol Exp Ther

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Bradykinin causes vasodilation, stimulates tissue-type plasminogen activator (t-PA) release and, in rodents, increases muscle glucose uptake. Although bradykinin causes vasodilation partly by activating nitric-oxide synthase (NOS), the role of nitric oxide in regulating bradykinin-stimulated t-PA release is uncertain. This study examined the effect of high-dose NOS inhibition on bradykinin-stimulated t-PA release and glucose uptake in humans. We studied 24 healthy (12 women and 12 men), overweight and obese (body mass index Ͼ25 kg/m 2 ), normotensive, nondiabetic subjects with normal cholesterol. We measured the effect of intra-arterial N -monomethyl-L-arginine (L-NMMA, 12 mol/min) on forearm blood flow (FBF), net t-PA release, and glucose uptake at baseline and in response to intra-arterial bradykinin (50 -200 ng/min) in subjects pretreated with the cyclooxygenase inhibitor aspirin. Measurements were repeated after isosorbide dinitrate (ISDN; 5 mg) or sildenafil (50 mg). L-NMMA decreased baseline FBF (P Ͻ 0.001), increased baseline forearm vascular resistance (P Ͻ 0.001), and increased the t-PA arterial-venous gradient (P ϭ 0.04) without affecting baseline net t-PA release or glucose uptake. During L-NMMA, ISDN tended to decrease baseline net t-PA release (P ϭ 0.06). L-NMMA blunted bradykinin-stimulated vasodilation (P Ͻ 0.001 for FBF and FVR). Bradykinin increased net glucose extraction (from Ϫ80 Ϯ 23 to Ϫ320 Ϯ 97 g/min/100 ml at 200 ng/min bradykinin, P ϭ 0.02), and L-NMMA (Ϫ143 Ϯ 50 g/ min/100 ml at 200 ng/min, P ϭ 0.045) attenuated this effect. In contrast, L-NMMA enhanced bradykinin-stimulated t-PA release (39.9 Ϯ 7.0 ng/min/100 ml versus 30.0 Ϯ 4.2 ng/min/100 ml at 200 ng/min, P ϭ 0.04 for L-NMMA). In gender-stratified analyses, L-NMMA significantly increased bradykinin-stimulated t-PA release in women (F ϭ 6.7, P ϭ 0.02) but not in men. Endogenous NO contributes to bradykinin-stimulated vasodilation and glucose uptake but attenuates the fibrinolytic response to exogenous bradykinin.Endothelial dysfunction, which is characterized by an impaired vasodilatory response to nitric-oxide synthase (NOS)-dependent agonists or by a decreased capacity of the endothelium to release tissue-type plasminogen activator (t-PA), predicts the development of cardiovascular events in patients at risk for coronary artery disease Robinson et al., 2007;Van Guilder et al., 2008). Endothelial t-PA release occurs through both constitutive and regulated pathways. In constitutive release, newly synthesized t-PA is transported directly from the Golgi apparatus to the cell membrane and secreted, even in the absence of an extracellular stimulus, whereas in regulated secretion, stored t-PA is released from endothelial granules in response to activation of membrane receptors (van den Eijnden-Schrauwen et al., 1995;Emeis et al., 1996;Parmer and Miles, 1998).The mechanisms governing the regulated secretion of t-PA are not completely understood. In vitro, in human microvascular endothelial cells, thrombin stimulates t-PA release via...

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Section: Discussionmentioning

confidence: 99%

Endogenous Nitric Oxide Contributes to Bradykinin-Stimulated Glucose Uptake but Attenuates Vascular Tissue-Type Plasminogen Activator Release

Pretorius

Brown²

2009

J Pharmacol Exp Ther

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“…Endothelial function was evaluated by the vasodilatation response, as described previously [7,10]. Briefly, the procedure consisted of infusions (through a 27-gauge needle inserted into the brachial artery of the non-dominant arm) of ACh (Daiichi Pharmaceutical) (in a stepwise fashion, from 50 nmol/min for 5 min to 100, 200 and 400 nmol/min for 3 min at each dose) or SNP (sodium nitroprusside) (3, 10 and 30 nmol/min), before and after the systemic intravenous infusion of normal saline (90 ml/h) and heparin (Shimizu Pharmaceutical) (0.3 unit/kg of body mass per min) (the control regimen) or lipid (Intralipid 20 %; Fresenius Kabi) (90 ml/h) and heparin (0.3 unit/kg of body mass per min) for 1 or 2 h. FBF (forearm blood flow) was measured bilaterally in the resting supine position by venous occlusion plethysmography with strain gauges, as described previously [7,10,27].…”

Section: Assessment Of Endothelial Function Before and After Lipid/hementioning

confidence: 99%

Dihydropyridine calcium channel blockers inhibit non-esterified-fatty-acid-induced endothelial and rheological dysfunction

et al. 2013

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Circulating NEFAs (non-esterified fatty acids) from adipose tissue lipolysis lead to endothelial dysfunction and insulin resistance in patients with the metabolic syndrome or Type 2 diabetes mellitus. The aim of the present study was to test the hypothesis that DHP (dihydropyridine) CCBs (calcium channel blockers) prevent NEFA-induced endothelial and haemorheological dysfunction independently of their antihypertensive properties. Using a double-blind cross-over study design, nifedipine, amlodipine, diltiazem or placebo were administered to eight healthy subjects for 2 days before each study day. On the study days, the following were assessed before and after the infusion of lipid and heparin to raise serum NEFAs: endothelial function, by measuring FBF (forearm blood flow) responses to ACh (acetylcholine); leucocyte activation, by ex vivo measurement of plasma MPO (myeloperoxidase) levels, adherent leucocyte numbers and whole blood transit time through microchannels; and oxidative stress, by determining plasma levels of d-ROMs (derivatives of reactive oxygen metabolites). Effects of the CCBs on NF-κB (nuclear factor κB) p65 phospholylation stimulated by NEFAs were assessed in cultured monocytic cells in vitro. Elevated NEFAs reduced the responses to ACh and significantly increased whole blood transit time, adherent leucocyte numbers and d-ROMs. Nifedipine and amlodipine, but not diltiazem, prevented NEFA-induced endothelial dysfunction, leucocyte activation and enhancement of oxidative stress without affecting BP (blood pressure), whereas all these drugs prevented NEFA-induced p65 activation in vitro. These results suggest that DHP CCBs, independent of their antihypertensive properties in humans, prevent NEFA-induced endothelial and haemorheological dysfunction through inhibition of NEFA-induced leucocyte activation, although the sensitivity to drugs of leucocyte Ca2+ channels may differ among cells.

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“…Forearm blood flow (FBF) was measured bilaterally by venous occlusion plethysmography with strain gauges, as described previously. 14,15 Assessment of Endothelial Function Before and After Lipid/Heparin Infusion All sterile solutions were freshly prepared before each study. ACh (Daiichi Pharmaceutical Co, Ltd) was infused at 50, 100, 200, and 400 nmol/min through a 27-gauge needle inserted into the brachial artery of the nondominant arm before and after systemic infusion of a fat emulsion (Intralipid 20%, Fresenius Kabi AB) at 90 mL/h and heparin (Shimizu Pharmaceutical Co, Ltd) at 0.3 U ⅐ kg Ϫ1 ⅐ min Ϫ1 for 1 hour.…”

Section: Forearm Blood Flow Measurementmentioning

confidence: 99%

“…The reduction in FBF by L-NMMA was restored by the nitric oxide (NO) clamp technique. 14 Changes in FBF response to ACh were measured before and after lipid/heparin infusion.…”

Section: Protocol 4: Effect Of Elevated Ffas On Ach-induced Vasodilatmentioning

confidence: 99%

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Inhibition of the Renin-Angiotensin System Prevents Free Fatty Acid–Induced Acute Endothelial Dysfunction in Humans

Watanabe

Tagawa

Yamakawa

et al. 2005

ATVB

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Objective-An elevated free fatty acid (FFA) level impairs endothelium-dependent vasodilation in humans, which may be pathophysiologically relevant to the development of endothelial dysfunction in patients with insulin resistance. We investigated the effect of inhibition of the renin-angiotensin system (RAS) on FFA-induced endothelial dysfunction. Methods and Results-Changes in forearm blood flow during intra-arterial infusion of acetylcholine were measured by plethysmography before and after systemic infusion of lipid/heparin in 10 healthy subjects given a single dose of placebo, losartan (50 mg), or perindopril (8 mg). Endothelial function after lipid/heparin infusion was also investigated with the coinfusion of vitamin C or N G -monomethyl-L-arginine (L-NMMA). Elevated FFA significantly reduced the response to acetylcholine by 37.7% (Pϭ0.0096) without L-NMMA, but not the response with L-NMMA, whereas FFA did not affect the response to nitroprusside. The single dose of either losartan or perindopril completely prevented FFA-induced endothelial dysfunction. Vitamin C also prevented FFA-induced endothelial dysfunction. Conclusions-Elevated FFA levels by lipid/heparin infusion, which may partly mimic the abnormal lipid profile in patients with insulin resistance, caused endothelial dysfunction via RAS activation and the presumably resultant oxidative stress in humans. Our results suggest the therapeutic rationale for RAS inhibition in patients with high FFA levels. Key Words: fatty acids Ⅲ endothelium Ⅲ angiotensin II Ⅲ insulin resistance Ⅲ nitric oxide A n increased plasma level of free fatty acid (FFA) may play pivotal roles in the development and progression of endothelial dysfunction and insulin resistance in patients with type 2 diabetes as well as in the prediabetic state, including the metabolic syndrome and visceral adiposity. 1,2 In addition to a negative correlation between plasma FFA levels and endothelial function, 3 a direct vascular effect of FFA on endothelial function in humans has already been demonstrated. FFAs elevated by lipid/heparin infusion significantly attenuated the vasodilatory response to acetylcholine (ACh) in healthy subjects. 2,4 Although it has been suggested that reactive oxygen species 4 -6 and activation of a stress-sensitive pathway like the transcriptional factor nuclear factor-B 7,8 may be involved in FFA-induced endothelial dysfunction, no specific therapeutic intervention has yet been established.Several randomized, clinical trials have suggested that inhibition of the renin-angiotensin system (RAS) is particularly effective in patients with diabetic hypertension compared with nondiabetic hypertension. 9,10 Improvement in endothelial function by angiotensin-converting enzyme (ACE) inhibitors 11 and angiotensin II type 1 receptor (AT 1 ) antagonists (ARB) 12 in type 2 diabetic patients may partly explain the results of previous randomized, clinical trials. Moreover, there is much evidence in support of enhanced activity of the RAS in obese, hypertensive patients. 13 In the pr...

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Methodological Validity and Feasibility of the Nitric Oxide Clamp Technique for Nitric Oxide Research in Human Resistant Vessels

Cited by 9 publications

References 31 publications

Endogenous Nitric Oxide Contributes to Bradykinin-Stimulated Glucose Uptake but Attenuates Vascular Tissue-Type Plasminogen Activator Release

Endogenous Nitric Oxide Contributes to Bradykinin-Stimulated Glucose Uptake but Attenuates Vascular Tissue-Type Plasminogen Activator Release

Dihydropyridine calcium channel blockers inhibit non-esterified-fatty-acid-induced endothelial and rheological dysfunction

Inhibition of the Renin-Angiotensin System Prevents Free Fatty Acid–Induced Acute Endothelial Dysfunction in Humans

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