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Colburn TD, Weber RE, Schulze KM, Sue Hageman K, Horn AG, Behnke BJ, Poole DC, Musch TI. Sexual dimorphism in vascular ATP-sensitive K + channel function supporting interstitial PO2 via convective and/or diffusive O 2 transport. J Physiol 2021; 599:3279-3293. [PMID: 34101850 PMCID: PMC8451062 DOI: 10.1113/jp281120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 04/14/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Inhibition of pancreatic ATP-sensitive K+ (KATP ) channels is the intended effect of oral sulphonylureas to increase insulin release in diabetes. However, pertinent to off-target effects of sulphonylurea medication, sex differences in cardiac KATP channel function exist, whereas potential sex differences in vascular KATP channel function remain unknown. In the present study, we assessed vascular KATP channel function (topical glibenclamide superfused onto fast-twitch oxidative skeletal muscle) supporting blood flow and interstitial O2 delivery-utilization matching ( P O 2 is) during twitch contractions in male, female during pro-oestrus and ovariectomized female (F+OVX) rats. Glibenclamide decreased blood flow (convective O2 transport) and interstitial P O 2 in male and female, but not F+OVX, rats. Compared to males, females also demonstrated impaired diffusive O2 transport and a faster fall in interstitial P O 2 . Our demonstration, in rats, that sex differences in vascular KATP channel function exist support the tentative hypothesis that oral sulphonylureas may exacerbate exercise intolerance and morbidity, especially in premenopausal females. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow ( Q ̇ m ), interstitial O2 delivery ( Q ̇ O 2 )-utilization ( V ̇ O 2 ) matching (i.e. interstitial-myocyte O2 flux driving pressure; P O 2 is) and exercise tolerance. Potential sex differences in skeletal muscle vascular KATP channel function remain largely unexplored. We hypothesized that local skeletal muscle KATP channel inhibition via glibenclamide superfusion (5 mg kg-1 GLI; sulphonylurea diabetes medication) in anaesthetized female Sprague-Dawley rats, compared to males, would demonstrate greater reductions in contracting (1 Hz, 7 V, 180 s) fast-twitch oxidative mixed gastrocnemius (97% type IIA+IID/X+IIB) Q ̇ m (15 μm microspheres) and P O 2 is (phosphorescence quenching), resulting from more compromised convective ( Q ̇ O 2 ) and diffusive ( D O 2 ) O2 conductances. Furthermore, these GLI-induced reductions in ovary-intact females measured during pro-oestrus would be diminished following ovariectomy (F+OVX). GLI similarly impaired mixed gastrocnemius V ̇ O 2 in both males (↓28%) and females (↓33%, both P < 0.032) via reduced Q ̇ m (male: ↓31%, female: ↓35%, both P < 0.020), Q ̇ O 2 (male: 5.6 ± 0.5 vs. 4.0 ± 0.5, female: 6.4 ± 1.1 vs. 4.2 ± 0.6 mL O2 min-1 100 g tissue-1 , P < 0.022) and the resulting P O 2 is, with females also demonstrating a reduced D O 2 (0.40 ± 0.07 vs. 0.30 ± 0.04 mL O2 min-1 100 g tissue-1 , P < 0.042) and a greater GLI-induced speeding of P O 2 is fall (mean response time: Sex × Drug interaction, P = 0.026). Conversely, GLI did not impair the mixed gastrocnemius of F+OVX rats. Therefore, in patients taking sulphonylureas, these results support the potential for impaired vascular KATP channel function to compromise muscle Q ̇ m and therefore exercise tolerance. Such an effect, if present, would likely contribute to adverse cardiovascular events in premenopausal females more than males.
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Affiliation(s)
- Trenton D. Colburn
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E. Weber
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M. Schulze
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K. Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Andrew G. Horn
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J. Behnke
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C. Poole
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I. Musch
- Department of Kinesiology, Physiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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Hypoxic Conditions Promote Rhythmic Contractile Oscillations Mediated by Voltage-Gated Sodium Channels Activation in Human Arteries. Int J Mol Sci 2021; 22:ijms22052570. [PMID: 33806419 PMCID: PMC7961413 DOI: 10.3390/ijms22052570] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/24/2021] [Accepted: 02/28/2021] [Indexed: 11/17/2022] Open
Abstract
Arterial smooth muscle exhibits rhythmic oscillatory contractions called vasomotion and believed to be a protective mechanism against tissue hypoperfusion or hypoxia. Oscillations of vascular tone depend on voltage and follow oscillations of the membrane potential. Voltage-gated sodium channels (Nav), responsible for the initiation and propagation of action potentials in excitable cells, have also been evidenced both in animal and human vascular smooth muscle cells (SMCs). For example, they contribute to arterial contraction in rats, but their physiopathological relevance has not been established in human vessels. In the present study, we investigated the functional role of Nav in the human artery. Experiments were performed on human uterine arteries obtained after hysterectomy and on SMCs dissociated from these arteries. In SMCs, we recorded a tetrodotoxin (TTX)-sensitive and fast inactivating voltage-dependent INa current. Various Nav genes, encoding α-subunit isoforms sensitive (Nav 1.2; 1.3; 1.7) and resistant (Nav 1.5) to TTX, were detected both in arterial tissue and in SMCs. Nav channels immunostaining showed uniform distribution in SMCs and endothelial cells. On arterial tissue, we recorded variations of isometric tension, ex vivo, in response to various agonists and antagonists. In arterial rings placed under hypoxic conditions, the depolarizing agent KCl and veratridine, a specific Nav channels agonist, both induced a sustained contraction overlaid with rhythmic oscillations of tension. After suppression of sympathetic control either by blocking the release of catecholamine or by antagonizing the target adrenergic response, rhythmic activity persisted while the sustained contraction was abolished. This rhythmic activity of the arteries was suppressed by TTX but, in contrast, only attenuated by antagonists of calcium channels, Na+/Ca2+ exchanger, Na+/K+-ATPase and the cardiac Nav channel. These results highlight the role of Nav as a novel key element in the vasomotion of human arteries. Hypoxia promotes activation of Nav channels involved in the initiation of rhythmic oscillatory contractile activity.
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Colburn TD, Weber RE, Hageman KS, Caldwell JT, Schulze KM, Ade CJ, Behnke BJ, Poole DC, Musch TI. Vascular ATP-sensitive K + channels support maximal aerobic capacity and critical speed via convective and diffusive O 2 transport. J Physiol 2020; 598:4843-4858. [PMID: 32798233 PMCID: PMC7874302 DOI: 10.1113/jp280232] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/13/2020] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS Oral sulphonylureas, widely prescribed for diabetes, inhibit pancreatic ATP-sensitive K+ (KATP ) channels to increase insulin release. However, KATP channels are also located within vascular (endothelium and smooth muscle) and muscle (cardiac and skeletal) tissue. We evaluated left ventricular function at rest, maximal aerobic capacity ( V ̇ O2 max) and submaximal exercise tolerance (i.e. speed-duration relationship) during treadmill running in rats, before and after systemic KATP channel inhibition via glibenclamide. Glibenclamide impaired critical speed proportionally more than V ̇ O2 max but did not alter resting cardiac output. Vascular KATP channel function (topical glibenclamide superfused onto hindlimb skeletal muscle) resolved a decreased blood flow and interstitial PO2 during twitch contractions reflecting impaired O2 delivery-to-utilization matching. Our findings demonstrate that systemic KATP channel inhibition reduces V ̇ O2 max and critical speed during treadmill running in rats due, in part, to impaired convective and diffusive O2 delivery, and thus V ̇ O2 , especially within fast-twitch oxidative skeletal muscle. ABSTRACT Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow and microvascular oxygen delivery-to-utilization matching during exercise. However, oral sulphonylurea treatment for diabetes inhibits pancreatic KATP channels to enhance insulin release. Herein we tested the hypotheses that: i) systemic KATP channel inhibition via glibenclamide (GLI; 10 mg kg-1 i.p.) would decrease cardiac output at rest (echocardiography), maximal aerobic capacity ( V ̇ O2 max) and the speed-duration relationship (i.e. lower critical speed (CS)) during treadmill running; and ii) local KATP channel inhibition (5 mg kg-1 GLI superfusion) would decrease blood flow (15 µm microspheres), interstitial space oxygen pressures (PO2 is; phosphorescence quenching) and convective and diffusive O2 transport ( Q ̇ O2 and DO2 , respectively; Fick Principle and Law of Diffusion) in contracting fast-twitch oxidative mixed gastrocnemius muscle (MG: 9% type I+IIa fibres). At rest, GLI slowed left ventricular relaxation (2.11 ± 0.59 vs. 1.70 ± 0.23 cm s-1 ) and decreased heart rate (321 ± 23 vs. 304 ± 22 bpm, both P < 0.05) while cardiac output remained unaltered (219 ± 64 vs. 197 ± 39 ml min-1 , P > 0.05). During exercise, GLI reduced V ̇ O2 max (71.5 ± 3.1 vs. 67.9 ± 4.8 ml kg-1 min-1 ) and CS (35.9 ± 2.4 vs. 31.9 ± 3.1 m min-1 , both P < 0.05). Local KATP channel inhibition decreased MG blood flow (52 ± 25 vs. 34 ± 13 ml min-1 100 g tissue-1 ) and PO2 isnadir (5.9 ± 0.9 vs. 4.7 ± 1.1 mmHg) during twitch contractions. Furthermore, MG V ̇ O2 was reduced via impaired Q ̇ O2 and DO2 (P < 0.05 for each). Collectively, these data support that vascular KATP channels help sustain submaximal exercise tolerance in healthy rats. For patients taking sulfonylureas, KATP channel inhibition may exacerbate exercise intolerance.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, 66506, USA
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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Colburn TD, Holdsworth CT, Craig JC, Hirai DM, Montgomery S, Poole DC, Musch TI, Kenney MJ. ATP-sensitive K + channel inhibition in rats decreases kidney and skeletal muscle blood flow without increasing sympathetic nerve discharge. Respir Physiol Neurobiol 2020; 278:103444. [PMID: 32330600 DOI: 10.1016/j.resp.2020.103444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 01/06/2023]
Abstract
ATP-sensitive K+ (KATP) channels contribute to exercise-induced hyperemia in skeletal muscle either locally by vascular hyperpolarization or by sympathoinhibition and decreased sympathetic vasoconstriction. However, mean arterial pressure (MAP) regulation via baroreceptors and subsequent efferent activity may confound assessment of vascular versus neural KATP channel function. We hypothesized that systemic KATP channel inhibition via glibenclamide (GLI) would increase MAP without increasing sympathetic nerve discharge (SND). Lumbar and renal nerve SND were measured in anesthetized male rats with intact baroreceptors (n = 12) and sinoaortic denervated (SAD; n = 4) counterparts and blood flow (BF) and vascular conductance (VC) assessed in conscious rats (n = 6). GLI increased MAP (p < 0.05) and transiently decreased HR in intact (p < 0.05), but not SAD rats. Renal (-30 %) and lumbar (-40 %) ΔSND decreased in intact but increased in SAD rats (∼40 % and 20 %; p < 0.05). BF and VC decreased in kidneys and total hindlimb skeletal muscle (p < 0.05). Thus, because KATP inhibition decreases SND, GLI-induced reductions in blood flow cannot result from enhanced sympathetic activity.
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Affiliation(s)
- Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA.
| | - Clark T Holdsworth
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA
| | - Daniel M Hirai
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA
| | - Shawnee Montgomery
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS 66506, USA; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA
| | - Michael J Kenney
- College of Science, University of Texas at El Paso, El Paso, TX 79902, USA
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 212] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Vascular K ATP channels mitigate severe muscle O 2 delivery-utilization mismatch during contractions in chronic heart failure rats. Respir Physiol Neurobiol 2017; 238:33-40. [PMID: 28119150 DOI: 10.1016/j.resp.2017.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/10/2017] [Accepted: 01/18/2017] [Indexed: 12/14/2022]
Abstract
The vascular ATP-sensitive K+ (KATP) channel is a mediator of skeletal muscle microvascular oxygenation (PO2mv) during contractions in health. We tested the hypothesis that KATP channel function is preserved in chronic heart failure (CHF) and therefore its inhibition would reduce PO2mv and exacerbate the time taken to reach the PO2mv steady-state during contractions of the spinotrapezius muscle. Moreover, we hypothesized that subsequent KATP channel activation would oppose the effects of this inhibition. Muscle PO2mv (phosphorescence quenching) was measured during 180s of 1-Hz twitch contractions (∼6V) under control, glibenclamide (GLI, KATP channel antagonist; 5mg/kg) and pinacidil (PIN, KATP channel agonist; 5mg/kg) conditions in 16 male Sprague-Dawley rats with CHF induced via myocardial infarction (coronary artery ligation, left ventricular end-diastolic pressure: 18±1mmHg). GLI reduced baseline PO2mv (control: 28.3±0.9, GLI: 24.8±1.0mmHg, p<0.05), lowered mean PO2mv (average PO2mv during the overall time taken to reach the steady-state; control: 20.6±0.6, GLI: 17.6±0.3mmHg, p<0.05), and slowed the attainment of steady-state PO2mv (overall mean response time; control: 66.1±10.2, GLI: 93.6±7.8s, p<0.05). PIN opposed these effects on the baseline PO2mv, mean PO2mv and time to reach the steady-state PO2mv (p<0.05 for all vs. GLI). Inhibition of KATP channels exacerbates the transient mismatch between muscle O2 delivery and utilization in CHF rats and this effect is opposed by PIN. These data reveal that the KATP channel constitutes one of the select few well-preserved mechanisms of skeletal muscle microvascular oxygenation control in CHF.
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Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:89-144. [PMID: 28212804 DOI: 10.1016/bs.apha.2016.07.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells.
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Holdsworth CT, Ferguson SK, Poole DC, Musch TI. Modulation of rat skeletal muscle microvascular O2 pressure via KATP channel inhibition following the onset of contractions. Respir Physiol Neurobiol 2016; 222:48-54. [DOI: 10.1016/j.resp.2015.11.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/16/2015] [Accepted: 11/14/2015] [Indexed: 11/26/2022]
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Holdsworth CT, Copp SW, Ferguson SK, Sims GE, Poole DC, Musch TI. Acute inhibition of ATP-sensitive K+ channels impairs skeletal muscle vascular control in rats during treadmill exercise. Am J Physiol Heart Circ Physiol 2015; 308:H1434-42. [PMID: 25820394 DOI: 10.1152/ajpheart.00772.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/25/2015] [Indexed: 10/23/2022]
Abstract
The ATP-sensitive K(+) (KATP) channel is part of a class of inward rectifier K(+) channels that can link local O2 availability to vasomotor tone across exercise-induced metabolic transients. The present investigation tested the hypothesis that if KATP channels are crucial to exercise hyperemia, then inhibition via glibenclamide (GLI) would lower hindlimb skeletal muscle blood flow (BF) and vascular conductance during treadmill exercise. In 27 adult male Sprague-Dawley rats, mean arterial pressure, blood lactate concentration, and hindlimb muscle BF (radiolabeled microspheres) were determined at rest (n = 6) and during exercise (n = 6-8, 20, 40, and 60 m/min, 5% incline, i.e., ~60-100% maximal O2 uptake) under control and GLI conditions (5 mg/kg intra-arterial). At rest and during exercise, mean arterial pressure was higher (rest: 17 ± 3%, 20 m/min: 5 ± 1%, 40 m/min: 5 ± 2%, and 60 m/min: 5 ± 1%, P < 0.05) with GLI. Hindlimb muscle BF (20 m/min: 16 ± 7%, 40 m/min: 30 ± 9%, and 60 m/min: 20 ± 8%) and vascular conductance (20 m/min: 20 ± 7%, 40 m/min: 33 ± 8%, and 60 m/min: 24 ± 8%) were lower with GLI during exercise at 20, 40, and 60 m/min, respectively (P < 0.05 for all) but not at rest. Within locomotory muscles, there was a greater fractional reduction present in muscles comprised predominantly of type I and type IIa fibers at all exercise speeds (P < 0.05). Additionally, blood lactate concentration was 106 ± 29% and 44 ± 15% higher during exercise with GLI at 20 and 40 m/min, respectively (P < 0.05). That KATP channel inhibition reduces hindlimb muscle BF during exercise in rats supports the obligatory contribution of KATP channels in large muscle mass exercise-induced hyperemia.
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Affiliation(s)
- Clark T Holdsworth
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and
| | - Steven W Copp
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and
| | - Scott K Ferguson
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and
| | - Gabrielle E Sims
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Timothy I Musch
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas; and Department of Kinesiology, Kansas State University, Manhattan, Kansas
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Shimada S, Todoki K, Omori Y, Toyama T, Matsuo M, Wada-Takahashi S, Takahashi SS, Lee MCI. Contribution of nitrergic nerve in canine gingival reactive hyperemia. J Clin Biochem Nutr 2015; 56:98-104. [PMID: 25759514 PMCID: PMC4345180 DOI: 10.3164/jcbn.14-71] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/19/2014] [Indexed: 11/22/2022] Open
Abstract
Reactive hyperemia reflects a compensatory vasodilation response of the local vasculature in ischemic tissue. The purpose of this study is to clarify the mechanism of regulation of this response in gingival circulation by using pharmacological analysis of reactive hyperemia and histochemical analysis of gingival tissue. Application of pressure to the gingiva was used to create temporary ischemia, and gingival blood flow was measured after pressure release. Reactive hyperemia increased in proportion to the duration of pressure. Systemic hemodynamics remained unaffected by the stimulus; therefore, the gingival reactive hyperemia reflected a local adjustment in circulation. Gingival reactive hyperemia was significantly suppressed by nitric oxide (NO) synthase inhibitors, especially the neural NO synthase-selective antagonist 7-nitroindazole, but not by anticholinergic drugs, β-blockers, or antihistaminergic drugs. Moreover, immunohistochemical staining for neural NO synthase and histochemical staining for NADPH diaphorase activity were both positive in the gingival perivascular region. These histochemical and pharmacological analyses show that reactive hyperemia following pressure release is mediated by NO-induced vasodilation. Furthermore, histochemical analysis strongly suggests that NO originates from nitrergic nerves. Therefore, NO may play an important role in the neural regulation of local circulation in gingival tissue ischemia.
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Affiliation(s)
- Shigeru Shimada
- Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Kazuo Todoki
- Department of Nursing, Junior College, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Yoichi Omori
- Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Toshizo Toyama
- Department of Infection Control, Division of Microbiology, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Masato Matsuo
- Department of Tissue-Engineering, Institute for Frontier Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Satoko Wada-Takahashi
- Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Shun-Suke Takahashi
- Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
| | - Masaichi-Chang-Il Lee
- Yokosuka-Shonan Disaster Health Emergency Research Center & ESR Laboratories, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan
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Khan F, Choong WL, Du Q, Jovanović A. Real-time RT-PCR threshold cycles value for Kir6.1 from the blood correlates with parameters of vascular function: a potential for the vascular function biomarker? Biomarkers 2013; 18:221-9. [PMID: 23480296 DOI: 10.3109/1354750x.2013.770553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Abstract We examined the presence of KATP channel subunits, Kir6.1 and SUR2B, mRNAs in the blood and vascular function in healthy volunteers (41 males, 34 females). Real-time reverse transcriptase (RT)-PCR threshold cycles (Ct) was used as an indicator of mRNA levels. Baseline skin perfusion and the post-occlusion reactive hyperemia response exhibited a significant positive correlation with Ct for Kir6.1. There was no correlation between Kir6.1 Ct and brachial artery flow-mediated dilatation. Gender had no influence on relationships between blood Kir6.1 Ct and vascular function. We conclude that blood Kir6.1 mRNA levels could be potentially used as a biomarker of the vascular function.
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Affiliation(s)
- Faisel Khan
- Medical Research Institute, Division of Cardiovascular and Diabetic Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, UK
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Differential effects of sulfonylurea derivatives on vascular ATP-sensitive potassium channels. Eur J Pharmacol 2012; 681:75-9. [DOI: 10.1016/j.ejphar.2012.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 02/09/2012] [Indexed: 12/25/2022]
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Palios J, Ikonomidis I, Lekakis J, Tsiodras S, Poulakou G, Antoniadou A, Panagopoulos P, Papadopoulos A, Giamarellou H, Anastasiou-Nana M, Kremastinos D. Microcirculatory vascular dysfunction in HIV-1 infected patients receiving highly active antiretroviral therapy. Microcirculation 2010; 17:303-10. [PMID: 20536743 DOI: 10.1111/j.1549-8719.2010.00023.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES We investigated whether HIV-1 infected patients receiving highly active antiretroviral therapy (HAART) and HIV-1 infected patients who had never received HAART had differences in their vascular microcirculatory function. METHODS We assessed the forearm blood flow before and after four minutes of ischemic occlusion of the brachial artery using venous occlusion strain gauge plethysmography. The hyperaemic forearm blood flow was recorded for three minutes at 15 second intervals. We calculated the maximal percent increase of the forearm blood flow during hyperemia. Forty HIV-infected male patients receiving HAART were compared to 20 age- and BMI- matched, male HIV-infected patients who had never received HAART (control group). RESULTS Patients on HAART had similar baseline forearm blood flow but lower maximal and percentage (%) change in forearm blood flow than control patients (4.2 +/- 1.7 vs. 4.1 +/- 1.7 l/ 100mL/min P = 0.8, 32 +/- 11.2 vs. 38.9 +/- 10.5 l/100 mL/min. P = 0.04 and 714 +/- 255 vs. 907 +/- 325%, P = 0.01, respectively). Patients receiving HAART had higher cholesterol than control patients (221 +/- 58 vs. 163 +/- 38 mg/dL, P = 0.001). HAART was associated with the percentage change in the blood flow during hyperemia (coefficient regression B = -0.32, P = 0.02) after adjustment for age, cholesterol and viral load. CONCLUSIONS HIV-infected patients receiving HAART present abnormalities of arterial microcirculation in comparison with never-treated patients.
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Affiliation(s)
- John Palios
- Second Department of Cardiology, Attikon University Hospital, University of Athens Medical School, Athens, Greece
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Meijer P, Wouters CW, van den Broek PHH, de Rooij M, Scheffer GJ, Smits P, Rongen GA. Upregulation of ecto-5'-nucleotidase by rosuvastatin increases the vasodilator response to ischemia. Hypertension 2010; 56:722-7. [PMID: 20679180 DOI: 10.1161/hypertensionaha.110.155689] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are effective in the primary and secondary prevention of cardiovascular events. Although originally developed to improve lipid profile, statins have demonstrated a surplus of beneficial pleiotropic effects, including improved endothelial function, reduced inflammation, and increased tolerance to ischemia-reperfusion injury. In preclinical studies, increased ecto-5'-nucleotidase activity, the key enzyme in extracellular adenosine formation, plays an important role in these effects. Because human data are absent, we explored the effects of rosuvastatin on ecto-5'-nucleotidase activity and the clinical relevance of increased extracellular adenosine during ischemia in humans in vivo. The forearm vasodilator responses to 3 increasing periods of forearm ischemia (2, 5, and 13 minutes) were determined during placebo and caffeine (an adenosine receptor antagonist) infusion into the brachial artery. At the end of an 8-day treatment period with rosuvastatin (20 mg per day), this whole procedure was repeated. During both experiments, ecto-5'-nucleotidase activity was determined. Vasodilator responses are expressed as the percentage increase in forearm blood flow ratio from baseline. Rosuvastatin increased ecto-5'-nucleotidase activity by 49±17% and enhanced the vasodilator response after 2, 5, and 13 minutes of ischemia in the absence (146±19, 330±26, and 987±133 to 312±77, 566±107, and 1533±267) but not in the presence of caffeine (98±25, 264±54, and 727±111 versus 95±19, 205±34, and 530±62). Rosuvastatin increases extracellular formation of adenosine in humans in vivo probably by enhancing ecto-5'-nucleotidase activity. This action results in the improvement of reactive hyperemia and may further enhance the clinical benefit of statins, in particular in conditions of ischemia.
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Affiliation(s)
- Patrick Meijer
- Departments of Pharmacology-Toxicology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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15
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Thaning P, Bune LT, Hellsten Y, Pilegaard H, Saltin B, Rosenmeier JB. Attenuated purinergic receptor function in patients with type 2 diabetes. Diabetes 2010; 59:182-9. [PMID: 19808895 PMCID: PMC2797920 DOI: 10.2337/db09-1068] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Extracellular nucleotides and nucleosides are involved in regulation of skeletal muscle blood flow. Diabetes induces cardiovascular dysregulation, but the extent to which the vasodilatatory capacity of nucleotides and nucleosides is affected in type 2 diabetes is unknown. The present study investigated 1) the vasodilatatory effect of ATP, uridine-triphosphate (UTP), and adenosine (ADO) and 2) the expression and distribution of P2Y(2) and P2X(1) receptors in skeletal muscles of diabetic subjects. RESEARCH DESIGN AND METHODS In 10 diabetic patients and 10 age-matched control subjects, leg blood flow (LBF) was measured during intrafemoral artery infusion of ATP, UTP, and ADO, eliciting a blood flow equal to knee-extensor exercise at 12 W (approximately 2.6 l/min). RESULTS The vasodilatatory effect of the purinergic system was 50% lower in the diabetic group as exemplified by an LBF increase of 274 +/- 37 vs. 143 +/- 26 ml/micromol ATP x kg, 494 +/- 80 vs. 234 +/- 39 ml/micromol UTP x kg, and 14.9 +/- 2.7 vs. 7.5 +/- 0.6 ml/micromol ADO x kg in control and diabetic subjects, respectively, thus making the vasodilator potency as follows: UTP control subjects (100) > ATP control subjects (55) > UTP diabetic subjects (47) > ATP diabetic subjects (29) > ADO control subjects (3) > ADO diabetic subjects (1.5). The distribution and mRNA expression of receptors were similar in the two groups. CONCLUSIONS The vasodilatatory effect of the purinergic system is severely reduced in type 2 diabetic patients. The potency of nucleotides varies with the following rank order: UTP > ATP > ADO. This is not due to alterations in receptor distribution and mRNA expression, but may be due to differences in receptor sensitivity.
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Affiliation(s)
- Pia Thaning
- Copenhagen Muscle Research Centre, Rigshospitalet, Denmark.
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Hojs N, Strucl M, Cankar K. The effect of glibenclamide on acetylcholine and sodium nitroprusside induced vasodilatation in human cutaneous microcirculation. Clin Physiol Funct Imaging 2009; 29:38-44. [DOI: 10.1111/j.1475-097x.2008.00833.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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17
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Dipyridamole enhances ischaemia-induced reactive hyperaemia by increased adenosine receptor stimulation. Br J Pharmacol 2008; 153:1169-76. [PMID: 18264130 DOI: 10.1038/bjp.2008.10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Dipyridamole enhances post-occlusive reactive hyperaemia (PORH) in the human forearm vascular bed. We hypothesize that this effect is completely mediated by increased adenosine receptor stimulation. To test this hypothesis, the effect of caffeine (an adenosine receptor antagonist) on dipyridamole-induced augmentation of PORH was explored. EXPERIMENTAL APPROACH The forearm vasodilator responses to three increasing periods of forearm ischaemia (2, 5 and 13 min) were determined during placebo infusion. Forty minutes after the last reperfusion period, this procedure was repeated during intra-arterial infusion of dipyridamole (7.4 nmol min(-1) per 100 ml forearm). At least 2 weeks later, this whole procedure was repeated, but now in the presence of caffeine (90 microg min(-1) per 100 ml volume). KEY RESULTS After 2, 5 and 13 min of ischaemia, the average forearm blood flow increased to 5.6+/-0.7, 9.7+/-1.3 and 34.5+/-2.1 ml min(-1) per 100 ml. After infusion of dipyridamole into the brachial artery, these numbers were significantly increased to 7.7+/-0.8, 12.5+/-1.5 and 41.6+/-3.1 ml min(-1) per 100 ml. This response was abolished by the concomitant infusion of caffeine (6.6+/-0.5, 10.2+/-0.6, 35.1+/-2.2 (caffeine) versus 7.4+/-0.4, 10.5+/-0.6, 33.7+/-2.2 ml min(-1)per 100 ml (caffeine/dipyridamole)). CONCLUSIONS AND IMPLICATIONS Caffeine prevented the augmenting effect of dipyridamole on PORH. This indicates that dipyridamole-induced augmentation of PORH is mediated via increased adenosine receptor stimulation as a result of elevated extracellular formation of adenosine during ischaemia.
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Cankar K, Strucl M. The effect of glibenclamide on cutaneous laser-Doppler flux. Microvasc Res 2008; 75:97-103. [PMID: 17675187 DOI: 10.1016/j.mvr.2007.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 05/28/2007] [Accepted: 06/15/2007] [Indexed: 11/26/2022]
Abstract
The K(ATP) channels play a crucial role in regulation of vascular tone in conditions of hypoxia. Whether they contribute to peripheral blood flow regulation in human cutaneous microcirculation during a non-hypoxic state is the matter of conflicting in vivo studies that have used plethysmographic method. Our aim was therefore to elucidate the role of K(ATP) channels in human skin microcirculation in three different conditions that evoke different interplays of vascular mechanisms; during resting conditions, during the postocclusive vasodilatation and in the vasoconstriction response to local cold exposure. The laser-Doppler (LD) skin response was monitored in 12 healthy volunteers on the skin of the fingertips of both hands at rest, after the release of an 8-min digital arteries occlusion, and during local cooling of one hand at 15 degrees C. We compared the direct (at the measuring site) and the indirect (at the contralateral non-cooled hand) LD flux response after intradermal microinjection of saline solution (1 mul) and after a microinjection of the K(ATP) channel blocker glibenclamide (8 muM saturated solution) at the measuring site after obtaining the dose-dependent effect of glibenclamide. The effect of the saline solution was used as a reference value. There was a statistically significant lower resting LD flux after the microinjection of glibenclamide 273.6+/-36 PU when compared to the values obtained after the application of the saline solution 375.8+/-31 PU (paired t-test, p=0.016). Glibenclamide also significantly reduced the relative area under the LD flux curve during the PRH response 14551+/-2508 PU*s vs. 6402+/-1476 PU*s (paired t-test, p=0.01) and increased the principal frequency of postocclusive PRH oscillations 0.0931+/-0.01 Hz vs. 0.1309+/-0.02 Hz (p=0.01). In addition, glibenclamide significantly decreased the LD flux during both the direct and indirect response to local cold exposure when compared to the application of saline solution (paired t-test, p<0.01). Our results support the conjecture that ATP sensitive K(+) channels are importantly involved in blood flow regulation of human skin microcirculation in PRH response, in resting conditions as well as in microvascular local cold response.
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Affiliation(s)
- Ksenija Cankar
- Institute of Physiology, School of Medicine, Zaloska 4, 1000 Ljubljana, Slovenia.
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Bilinska M, Potocka J, Korzeniowska-Kubacka I, Piotrowicz R. 'Warm-up' phenomenon in diabetic patients with stable angina treated with diet or sulfonylureas. Coron Artery Dis 2007; 18:455-62. [PMID: 17700217 DOI: 10.1097/mca.0b013e3282a30676] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Classic sulfonyloureas (SUs) are known to attenuate ischaemic preconditioning. Gliclazide is an SU agent believed to be more protective. We assessed the effects of diet, glibenclamide, or gliclazide on the warm-up effect in type 2 diabetic patients with stable angina. METHODS The study group consisted of 64 men, aged 54+/-5 years: 17 patients without diabetes (G I) and 47 diabetic patients: 16 patients treated with glibenclamide (G II), 16 with gliclazide (G III) and 15 patients treated with diet (G IV). After the baseline positive exercise test (ET1), all patients reexercised after 30-min rest (ET2). We analysed exercise duration (ED, s), time to 1 mm ST depression (T-STD, s), max STD (mm), heart rate-systolic blood pressure product at 1 mm STD, or ischaemic threshold (mmHg/min x 100) and the total ischaemic time (s). RESULTS In G I, all analysed variables improved significantly during ET2 relative to ET1. Glibenclamide (G II) completely abolished the protective effect of exercise-induced ischaemia because only ED increased during ET2 (431 vs. 451, P<0.05). In G III, however, ED (486 vs. 537, P<0.001), T-STD (364 vs. 388, P<0.05) and max STD (2.5 vs. 2.0, P<0.05) improved significantly during ET2, whereas ischaemic threshold and total ischaemic time did not (PNS). In G IV, similar to G I, all variables improved significantly during ET2 relative to ET1. CONCLUSION Warm-up effect is preserved in diabetic patients with stable angina treated with diet, partially preserved in gliclazide-treated and abolished in glibenclamide-treated patients.
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Affiliation(s)
- Maria Bilinska
- Department of Cardiac Rehabilitation and Noninvasive Electrocardiology, Institute of Cardiology, Warsaw, Poland.
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20
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Bubolz AH, Wu Q, Larsen BT, Gutterman DD, Liu Y. Ebselen reduces nitration and restores voltage-gated potassium channel function in small coronary arteries of diabetic rats. Am J Physiol Heart Circ Physiol 2007; 293:H2231-7. [PMID: 17675568 DOI: 10.1152/ajpheart.00717.2007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Small coronary arteries (SCA) from diabetic rats exhibit enhanced peroxynitrite (ONOO(-)) formation and concurrent impairment of voltage-dependent potassium (K(v)) channel function. However, it is unclear whether ONOO(-) plays a causative role in this impairment. We hypothesized that functional loss of K(v) channels in coronary smooth muscle cells (SMC) in diabetes is due to ONOO(-) with subsequent tyrosine nitration of K(v) channel proteins. Diabetic rats and nondiabetic controls were treated with or without ebselen (Eb) for 4 wk. SCA were prepared for immunohistochemistry (IHC), immunoprecipitation (IP) followed by Western blot (WB), videomicroscopy, and patch-clamp analysis. IHC revealed excess ONOO(-) in SCA from diabetic rats. IP and WB revealed elevated nitration of the K(v)1.2 alpha-subunit and reduced K(v)1.2 protein expression in diabetic rats. Each of these changes was improved in Eb-treated rats. Protein nitration and K(v)1.5 expression were unchanged in SCA from diabetic rats. Forskolin, a direct cAMP activator that induces K(v)1 channel activity, dilated SCA from nondiabetic rats in a correolide (Cor; a selective K(v)1 channel blocker)-sensitive fashion. Cor did not alter the reduced dilation to forskolin in diabetic rats; however, Eb partially restored the Cor-sensitive component of dilation. Basal K(v) current density and response to forskolin were improved in smooth muscle cells from Eb-treated DM rats. We conclude that enhanced nitrosative stress in diabetes mellitus contributes to K(v)1 channel dysfunction in the coronary microcirculation. Eb may be beneficial for the therapeutic treatment of vascular complications in diabetes mellitus.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Antioxidants/pharmacology
- Antioxidants/therapeutic use
- Azoles/pharmacology
- Azoles/therapeutic use
- Colforsin/pharmacology
- Coronary Vessels/drug effects
- Coronary Vessels/enzymology
- Coronary Vessels/metabolism
- Coronary Vessels/physiopathology
- Cyclic AMP/metabolism
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Dose-Response Relationship, Drug
- Enzyme Activators/pharmacology
- Isoindoles
- Kv1.2 Potassium Channel/drug effects
- Kv1.2 Potassium Channel/metabolism
- Kv1.5 Potassium Channel/drug effects
- Kv1.5 Potassium Channel/metabolism
- Male
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiopathology
- Organoselenium Compounds/pharmacology
- Organoselenium Compounds/therapeutic use
- Oxidative Stress/drug effects
- Peroxynitrous Acid/metabolism
- Potassium Channel Blockers/pharmacology
- Protein Subunits
- Rats
- Rats, Sprague-Dawley
- Research Design
- Triterpenes/pharmacology
- Tyrosine/analogs & derivatives
- Tyrosine/metabolism
- Vasodilation/drug effects
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Affiliation(s)
- Aaron H Bubolz
- Department of Medicine, The Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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21
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Hughes SF, Hendricks BD, Edwards DR, Bastawrous SS, Roberts GE, Middleton JF. Mild episodes of tourniquet-induced forearm ischaemia-reperfusion injury results in leukocyte activation and changes in inflammatory and coagulation markers. JOURNAL OF INFLAMMATION-LONDON 2007; 4:12. [PMID: 17537260 PMCID: PMC1890284 DOI: 10.1186/1476-9255-4-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Accepted: 05/30/2007] [Indexed: 11/21/2022]
Abstract
Background Monocytes and neutrophils are examples of phagocytic leukocytes, with neutrophils being considered as the 'chief' phagocytic leukocyte. Both monocytes and neutrophils have been implicated to play a key role in the development of ischaemia-reperfusion injury, where they are intrinsically involved in leukocyte-endothelial cell interactions. In this pilot study we hypothesised that mild episodes of tourniquet induced forearm ischaemia-reperfusion injury results in leukocyte activation and changes in inflammatory and coagulation markers. Methods Ten healthy human volunteers were recruited after informed consent. None had any history of cardiovascular disease with each subject volunteer participating in the study for a 24 hour period. Six venous blood samples were collected from each subject volunteer at baseline, 10 minutes ischaemia, 5, 15, 30, 60 minutes and 24 hours reperfusion, by means of a cannula from the ante-cubital fossa. Monocyte and neutrophil leukocyte sub-populations were isolated by density gradient centrifugation techniques. Leukocyte trapping was investigated by measuring the concentration of leukocytes in venous blood leaving the arm. The cell surface expression of CD62L (L-selectin), CD11b and the intracellular production of hydrogen peroxide (H2O2) were measured via flow cytometry. C-reactive protein (CRP) was measured using a clinical chemistry analyser. Plasma concentrations of D-dimer and von Willebrand factor (vWF) were measured using enzyme-linked fluorescent assays (ELFA). Results During ischaemia-reperfusion injury, there was a decrease in CD62L and an increase in CD11b cell surface expression for both monocytes and neutrophils, with changes in the measured parameters reaching statistical significance (p =< 0.05). A significant decrease in peripheral blood leukocyte concentration was observed during this process, which was measured to assess the degree of leukocyte trapping in the micro-circulation (p =< 0.001). There was an increase in the intracellular production of H2O2 production by leukocyte sub-populations, which was measured as a marker of leukocyte activation. Intracellular production of H2O2 in monocytes during ischaemia-reperfusion injury reached statistical significance (p = 0.014), although similar trends were observed with neutrophils these did not reach statistical significance. CRP was measured to assess the inflammatory response following mild episodes of ischaemia-reperfusion injury and resulted in a significant increase in the CRP concentration (p =< 0.001). There were also increased plasma concentrations of D-dimer and a trend towards elevated vWF levels, which were measured as markers of coagulation activation and endothelial damage respectively. Although significant changes in D-dimer concentrations were observed during ischaemia-reperfusion injury (p = 0.007), measurement of the vWF did not reach statistical significance. Conclusion Tourniquet induced forearm ischaemia-reperfusion injury results in increased adhesiveness, trapping and activation of leukocytes. We report that, even following a mild ischaemic insult, this leukocyte response is immediately followed by evidence of increased inflammatory response, coagulation activity and endothelial damage. These results may have important implications and this pilot study may lead to a series of trials that shed light on the mechanisms of ischaemia-reperfusion injury, including potential points of therapeutic intervention for pathophysiological conditions.
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Affiliation(s)
- Stephen F Hughes
- Chemical Pathology Department, Glan Clwyd Hospital, Sarn Lane, Rhyl, Denbighshire, UK
- Leopold Muller Arthritis Research Centre, School of Medicine, Keele University at Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK
| | - Beverly D Hendricks
- Haematology Department, Glan Clwyd Hospital, Sarn Lane, Rhyl, Denbighshire, UK
| | - David R Edwards
- Haematology Department, Gwynedd Hospital, Penrhosgarnedd, Bangor, Gwynedd, UK
| | - Salah S Bastawrous
- Orthopaedics Department, Glan Clwyd Hospital, Sarn Lane, Rhyl, Denbighshire, UK
| | - Gareth E Roberts
- Anaesthetics Department, Gwynedd Hospital, Penrhosgarnedd, Bangor, Gwynedd, UK
| | - Jim F Middleton
- Leopold Muller Arthritis Research Centre, School of Medicine, Keele University at Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK
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Gobron C, Vahedi K, Vicaut E, Stucker O, Laemmel E, Baudry N, Bousser MG, Chabriat H. Characteristic features of in vivo skin microvascular reactivity in CADASIL. J Cereb Blood Flow Metab 2007; 27:250-7. [PMID: 16788714 DOI: 10.1038/sj.jcbfm.9600356] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) is caused by mutations in the Notch3 receptor expressed at the surface of vascular smooth muscle cells. The functional consequences of the disease at the peripheral microcirculation level are incompletely elucidated. In this study, we aimed to assess, in vivo, the endothelium-dependent and independent vasodilation of the skin microvasculature in CADASIL patients. Twenty-three affected subjects were compared with 23 gender and age-matched controls. The brachial artery endothelium-dependent and endothelium-independent vasodilation were assessed after forearm cuff occlusion and nitroglycerin administration. Skin vasoreactivity to transcutaneous administration of acetylcholine and sodium nitroprussiate, and after postocclusive hyperemia were measured by Laser Doppler flowmetry. The maximum changes in the diameter of the brachial artery after the cuff release or after nitroglycerin administration did not differ between patients and controls. With iontopheresis, only the peak value of the dose response was found decreased in normocholesterolemic patients after nitroprussiate administration. The postocclusive test revealed a large increase of the time to peak value and whole duration of the hyperemic response in CADASIL patients. The results of this study show that the skin vasoreactivity is altered in CADASIL. Particularly, the kinetics of reactive hyperemia after cuff occlusion is dramatically changed with a lengthened and delayed response. This characteristic pattern may be related to the specific ultrastructural modifications related to Notch3 gene mutations involving smooth muscle cells in the microvasculature.
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Affiliation(s)
- Claire Gobron
- Department of Neurology, CHU Lariboisière, Assistance Publique des Hôpitaux de Paris, Paris, France
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23
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Mortensen UM, Nielsen-Kudsk JE, Sondergaard HM, Jakobsen P, Jensen BS, Schmitz O, Nielsen TT. Effect of the oral hypoglycaemic sulphonylurea glibenclamide, a blocker of ATP-sensitive potassium channels, on walking distance in patients with intermittent claudication. Diabet Med 2006; 23:327-30. [PMID: 16492219 DOI: 10.1111/j.1464-5491.2006.01797.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The oral hypoglycaemic sulphonylurea glibenclamide stimulates endogenous insulin secretion through blockade of ATP-sensitive potassium (KATP) channels on pancreatic beta cells, but also blocks cardiovascular KATP channels, leading to increased peripheral vascular resistance and reduced peripheral blood flow in non-diabetic subjects. Therefore, this study examined whether a single oral dose of glibenclamide adversely affected the pain-free or maximal walking distance in patients with intermittent claudication. METHODS In a double-blind, randomized crossover study, 12 non-diabetic patients with intermittent claudication were given a single oral dose of glibenclamide (5.25 mg) or placebo separated by a washout period of 1 week. A treadmill test was carried out 180 min after glibenclamide/placebo intake for determination of pain-free and maximal walking distance. Plasma glucose concentrations were kept constant by an euglycemic clamp. Changes in ankle/brachial blood pressure index (ABI), serum insulin, and serum glibenclamide were also assessed. RESULTS The pain-free walking distance was 62.8 +/- 9.8 metres (mean +/- sem) after glibenclamide and 52.6 +/- 5.9 metres after placebo (P = 0.52). The maximal walking distance was 142.7 +/- 18.7 metres after glibenclamide and 132.6 +/- 16.6 metres after placebo (P = 0.23). The ABI was not significantly changed by glibenclamide compared with placebo. Serum glibenclamide was 0.51 +/- 0.08 microm 180 min after administration of the drug. Glibenclamide produced an 8-fold increase in circulating insulin compared with placebo (P < 0.001). CONCLUSIONS Glibenclamide given as a single oral dose commonly used in glucose-lowering drug therapy does not reduce pain-free or maximal walking distance in non-diabetic patients with intermittent claudication.
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Affiliation(s)
- U M Mortensen
- Department of Cardiology B, Aarhus University Hospital, Aarhus, Denmark
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24
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Schrage WG, Dietz NM, Joyner MJ. Effects of combined inhibition of ATP-sensitive potassium channels, nitric oxide, and prostaglandins on hyperemia during moderate exercise. J Appl Physiol (1985) 2006; 100:1506-12. [PMID: 16469932 DOI: 10.1152/japplphysiol.01639.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ATP-sensitive potassium (KATP) channels have been suggested to contribute to coronary and skeletal muscle vasodilation during exercise, either alone or interacting in a parallel or redundant process with nitric oxide (NO), prostaglandins (PGs), and adenosine. We tested the hypothesis that KATP channels, alone or in combination with NO and PGs, regulate exercise hyperemia in forearm muscle. Eighteen healthy young adults performed 20 min of moderate dynamic forearm exercise, with forearm blood flow (FBF) measured via Doppler ultrasound. After steady-state FBF was achieved for 5 min (saline control), the KATP inhibitor glibenclamide (Glib) was infused into the brachial artery for 5 min (10 microg.dl(-1).min(-1)), followed by saline infusion during the final 10 min of exercise (n = 9). Exercise increased FBF from 71 +/- 11 to 239 +/- 24 ml/min, and FBF was not altered by 5 min of Glib. Systemic plasma Glib levels were above the therapeutic range, and Glib increased insulin levels by approximately 50%, whereas blood glucose was unchanged (88 +/- 2 vs. 90 +/- 2 mg/dl). In nine additional subjects, Glib was followed by combined infusion of NG-nitro-L-arginine methyl ester (L-NAME) plus ketorolac (to inhibit NO and PGs, respectively). As above, Glib had no effect on FBF but addition of L-NAME + ketorolac (i.e., triple blockade) reduced FBF by approximately 15% below steady-state exercise levels in seven of nine subjects. Interestingly, triple blockade in two subjects caused FBF to transiently and dramatically decrease. This was followed by an acute recovery of flow above steady-state exercise values. We conclude 1) opening of KATP channels is not obligatory for forearm exercise hyperemia, and 2) triple blockade of NO, PGs, and KATP channels does not reduce hyperemia more than the inhibition of NO and PGs in most subjects. However, some subjects are sensitive to triple blockade, but they are able to restore FBF acutely during exercise. Future studies are required to determine the nature of these compensatory mechanisms in the affected individuals.
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Affiliation(s)
- William G Schrage
- Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA.
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ter Avest E, Abbink EJ, Holewijn S, de Graaf J, Tack CJ, Stalenhoef AFH. Effects of rosuvastatin on endothelial function in patients with familial combined hyperlipidaemia (FCH). Curr Med Res Opin 2005; 21:1469-76. [PMID: 16197666 DOI: 10.1185/030079905x61910] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Although several studies have reported a positive effect of statins on endothelial vasoreactivity, most studies performed in subjects with type 2 diabetes mellitus report no effect at all. This lack of effect may be related to the existence of insulin resistance, or to insufficient lowering of atherogenic (apo)lipoproteins. Therefore, we tested in this study whether treatment of insulin resistant familial combined hyperlipidaemia (FCH) patients with a high dose (40 mg/day) of the potent rosuvastatin was able to improve endothelial function, without necessarily improving insulin sensitivity. RESEARCH DESIGN AND METHODS In a double-blind randomised crossover study, 18 subjects with FCH (without evident cardiovascular disease, mean [standard deviation] age 54 [7] years) underwent a 4-week run-in period after which they were randomised to treatment with placebo once daily for 12 weeks, followed by rosuvastatin 40 mg/day for 12 weeks or vice versa. Endothelial function was determined after 8 and 12 weeks of both treatment periods, respectively, by measurement of flow-mediated vasodilation (FMD) using high-resolution ultrasound and by measurement of vasodilator response to intrabrachial acetylcholine (Ach) by venous occlusion plethysmography (forearm blood flow [FBF]). RESULTS Plasma levels of lipids, (apo)lipoproteins and high-sensitivity C-reactive protein (hsCRP) improved significantly after rosuvastatin therapy compared to placebo. However, rosuvastatin had no effect on homeostasis model assessment (HOMA)-indices or on vasodilator responses to intra-brachial acetylcholine-infusion (FBF-ratio increased from a mean of 1.28 [SD: 0.46] to 5.82 [3.44] after rosuvastatin and from 1.33 [0.67] to 5.99 [3.89] after placebo, p = 0.35). Endothelium-dependent FMD was also unchanged (1.6% [3.1%] vs. 3.2% [3.5]%, p = 0.56 rosuvastatin vs. placebo, respectively). CONCLUSION In patients with FCH, a 12-week treatment of rosuvastatin 40 mg/day did not improve endothelial function (either in large conduit vessels or in resistance vessels), despite significant improvements in plasma lipids, (apo)lipoproteins. and low-grade inflammation.
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Affiliation(s)
- Ewoud ter Avest
- Department of Medicine, Division of General Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Robertshaw HJ, McAnulty GR, Hall GH. Strategies for managing the diabetic patient. Best Pract Res Clin Anaesthesiol 2004; 18:631-43. [PMID: 15460549 DOI: 10.1016/j.bpa.2004.05.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Diabetes mellitus is now classified as either 'type 1' (failure of endogenous insulin production) or 'type 2' ('insulin resistance') and can be diagnosed if fasting blood glucose is >6.1 mmol/l (110mg/dl) on two separate occasions or there is unequivocal hyperglycaemia with acute metabolic decompensation or obvious symptoms. The prevalence of the disease is rising and may be as great as 12-14% in western populations aged over 40 years. Diabetes is complicated by micro- and macrovascular consequences of chronically elevated blood glucose concentrations, and diabetic patients are over-represented in hospital populations, particularly among patients requiring surgical interventions. It is associated with increased perioperative mortality and morbidity. Evidence is now accumulating that intensive glycaemic monitoring and the administration of insulin infusions to achieve tight glycaemic control are associated with an improvement of both perioperative mortality and morbidity.
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Affiliation(s)
- Heidi J Robertshaw
- St George's Hospital Medical School, Cranmer Terrace, London SWI7 0RE, UK
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Spallarossa P, Barsotti A, Cordera R, Ghigliotti G, Maggi D, Brunelli C. Reduction of cardiovascular morbidity and mortality in type 2 diabetes. A rational approach to hypoglycemic therapy. J Endocrinol Invest 2004; 27:485-95. [PMID: 15279085 DOI: 10.1007/bf03345297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus is the single most important risk factor for the development of coronary artery disease. Unfortunately, the traditional therapeutic strategies for the treatment of hyperglycemia have proven to be ineffective in preventing cardiovascular complications. In recent years the number of available hypoglycemic agents has increased and considerable progress has been made regarding the comprehension of the pathophysiology of diabetes and its vascular complications. In the present article we firstly present benefits and risks of intensive vs standard hypoglycemic intervention, and the pros and cons of therapy targeted to postprandial hyperglycemia. Secondly, we discuss the cardiovascular effects of sulfonylurea agents and insulin, focusing on the role of intensive insulin treatment in the context of acute coronary syndromes. Thirdly, we review the epidemiological, clinical and experimental evidence linking insulin resistance and cardiovascular disease. Finally, we present the rationale and the role of metformin and thiazolidinedionetherapy in the prevention of cardiovascular complications. We conclude that the optimal use of the full spectrum of hypoglycemic agents has the potential to play a key role in the prevention of diabetes-related macrovascular complications.
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Affiliation(s)
- P Spallarossa
- Division of Cardiology, Department of Internal Medicine, University of Genoa, Italy.
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Jansson L, Kullin M, Karlsson FA, Bodin B, Hansen JB, Sandler S. K(ATP) channels and pancreatic islet blood flow in anesthetized rats: increased blood flow induced by potassium channel openers. Diabetes 2003; 52:2043-8. [PMID: 12882921 DOI: 10.2337/diabetes.52.8.2043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
K(ATP) channels are important for insulin secretion and depolarization of vascular smooth muscle. In view of the importance of drugs affecting K(ATP) channels in the treatment of diabetes, we investigated the effects of these channels on splanchnic blood perfusion in general and pancreatic islet blood flow in particular. We treated anesthetized Sprague-Dawley rats with the K(ATP) channel openers diazoxide or NNC 55-0118 or the K(ATP) channel closer glipizide. Both diazoxide and NNC 55-0118 dose-dependently increased total pancreatic and islet blood flow in the presence of moderate hyperglycemia, but had no effects on the blood perfusion of other splanchnic organs. Diazoxide markedly lowered the mean arterial blood pressure and thus increased vascular conductance in all organs studied. NNC 55-0118 had much smaller effects on the blood pressure. Glipizide did not affect total pancreatic blood flow, but decreased islet blood flow by 50% in the presence of hypoglycemia. We conclude that K(ATP) channels actively participate in the blood flow regulation of the pancreatic islets and that substances affecting such channels may also influence islet blood flow.
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Affiliation(s)
- Leif Jansson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
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Riveline JP, Danchin N, Ledru F, Varroud-Vial M, Charpentier G. Sulfonylureas and cardiovascular effects: from experimental data to clinical use. Available data in humans and clinical applications. DIABETES & METABOLISM 2003; 29:207-22. [PMID: 12909809 DOI: 10.1016/s1262-3636(07)70030-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES 33 years after the UGDP study, the question of deleterious effects of the sulfoylurea (SU) is still raised. We have made a systematic review of the literature from experimental studies to clinical and epidemiological studies. RESULTS The main molecule studied is glibenclamide (GB). In vitro and in animal studies, GB is both deleterious for ischemic preconditionning (IPC) and protective for arrhythmia during acute ischemia. Glimepiride (GM) and gliclazide (GCZ) do not seem to have effect on IPC. These effects have been few studied in diabetic animals. In human, according to the investigations used, the GB seems nil or suppressing for IPC, it seems elsewhere decreases ventricular arrhythmias during periods of acute ischemia. It is possible that these two actions account for the non-appearance of concordant deleterious effects between short and long-term studies. With regards to other drugs, only the GM has been specifically studied in human and appears to be nil on IPC. The only prospective clinical study available, although not having for objective to answer to this question, is the UKPDS study. This trial demonstrates the absence of deleterious cardiac effects of GB compared to chlorpropamide and particularly compared to insulin. CONCLUSION In conclusion, in experimental studies the cardiac effects of SU differ: both deleterious and protective for GB, nil for GM and GCZ on IPC. In all cases the clinical consequences seems to be nil.
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Affiliation(s)
- J P Riveline
- Department of Diabetology, Sud-Francilien Hospital, Corbeil, France.
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Farouque HMO, Meredith IT. Inhibition of vascular ATP-sensitive K+ channels does not affect reactive hyperemia in human forearm. Am J Physiol Heart Circ Physiol 2003; 284:H711-8. [PMID: 12529259 DOI: 10.1152/ajpheart.00315.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The extent to which ATP-sensitive K(+) channels contribute to reactive hyperemia in humans is unresolved. We examined the role of ATP-sensitive K(+) channels in regulating reactive hyperemia induced by 5 min of forearm ischemia. Thirty-one healthy subjects had forearm blood flow measured with venous occlusion plethysmography. Reactive hyperemia could be reproducibly induced (n = 9). The contribution of vascular ATP-sensitive K(+) channels to reactive hyperemia was determined by measuring forearm blood flow before and during brachial artery infusion of glibenclamide, an ATP-sensitive K(+) channel inhibitor (n = 12). To document ATP-sensitive K(+) channel inhibition with glibenclamide, coinfusion with diazoxide, an ATP-sensitive K(+) channel opener, was undertaken (n = 10). Glibenclamide did not significantly alter resting forearm blood flow or the initial and sustained phases of reactive hyperemia. However, glibenclamide attenuated the hyperemic response induced by diazoxide. These data suggest that ATP-sensitive K(+) channels do not play an important role in controlling forearm reactive hyperemia and that other mechanisms are active in this adaptive response.
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Affiliation(s)
- H M Omar Farouque
- Cardiovascular Research Centre, Monash Medical Centre and Monash University, Melbourne, Victoria, 3168, Australia
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Saltman AE, Aksehirli TO, Valiunas V, Gaudette GR, Matsuyama N, Brink P, Krukenkamp IB. Gap junction uncoupling protects the heart against ischemia. J Thorac Cardiovasc Surg 2002; 124:371-6. [PMID: 12167798 DOI: 10.1067/mtc.2002.124239] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Many stimuli can successfully protect the heart against ischemia. We investigated whether gap junction uncoupling before ischemia was myoprotective. We also studied the function of the adenosine triphosphate-dependent potassium channel, which has been implicated in the mechanism of pharmacologic preconditioning, with respect to gap junction physiology. METHODS Twenty-eight rabbit hearts were placed on a Langendorff perfusion apparatus. Five were given a 5-minute infusion of 1 mmol/L heptanol (a gap junction uncoupler), 5 were given 10 micromol/L 2,3-butanedione monoxime (an electromechanical uncoupler), and 6 were given no drug. The left anterior descending coronary artery was then occluded for 1 hour and reperfused for 2 hours. Six hearts received 10 micromol/L glybenclamide before heptanol to evaluate the role of the adenosine triphosphate-dependent potassium channel. Six hearts underwent ischemic preconditioning with 2 cycles of 5 minutes of global ischemia and reperfusion. Action-potential duration of the ischemic zone, left ventricular developed pressure, and coronary flow were measured continuously. Infarct size was determined at the end of reperfusion. RESULTS Heptanol significantly reduced infarct size (from 46% +/- 2% to 22% +/- 5%, P <.01), an effect that was not prevented by glybenclamide. Butanedione monoxime decreased developed pressure but did not significantly reduce infarct size (46% +/- 5% vs 46% +/- 2%, P = not significant). There were no differences among groups with regard to developed pressure or action-potential duration. CONCLUSION Directly blocking gap junctions preconditions the heart. This protection is not a direct result of a decrease in developed pressure before a prolonged ischemic period nor is it achieved through a mechanism involving the adenosine triphosphate-dependent potassium channel.
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Affiliation(s)
- Adam E Saltman
- Division of Cardiothoracic Surgery, The Institute for Molecular Cardiology, State University of New York at Stony Brook, Health Sciences Center T19-080, Stony Brook, NY 11794-8191, USA.
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Abbink EJ, Wollersheim H, Netten PM, Russel FGM, Lutterman JA, Smits P. Microcirculatory effects of KATP channel blockade by sulphonylurea derivatives in humans. Eur J Clin Invest 2002; 32:163-71. [PMID: 11895467 DOI: 10.1046/j.1365-2362.2002.00964.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Recent investigations have shown that glibenclamide inhibits the opening of vascular ATP-sensitive potassium channels during ischemia. This observation may implicate cardiovascular effects of sulphonylurea derivatives when used under conditions of ischemia in patients with Type 2 diabetes mellitus. In addition to resistance arteries, the (pre) capillary vessels also contain ATP-dependent potassium channels. Closure of these channels by sulphonylurea derivatives might affect the development of microvascular disease in Type 2 diabetes mellitus. Therefore, we investigated the microcirculatory effects of sulphonylurea derivatives in Type 2 diabetic patients as compared with healthy volunteers. MATERIALS AND METHODS Arteriovenous blood flow (skin temperature and laser Doppler flux) and capillary blood cell velocity were measured before and during infusion of four doses of glibenclamide (0.1, 0.3, 1.0 and 3.0 microg min-1 dL-1) into the brachial artery of 14 Type 2 diabetic patients and 13 healthy controls. The experiments included appropriate time control studies. RESULTS Both skin temperature and laser Doppler flux decreased in response to glibenclamide in healthy volunteers (-7 +/- 2%, P < 0.0005 and -31 +/- 11%, P = 0.001, respectively), but did not change in Type 2 diabetic patients (1 +/- 3%, P = 0.29 and 4 +/- 14%, P = 0.97). However, capillary blood cell velocity decreased in Type 2 diabetic patients (-38 +/- 18%, P = 0.04), but did not change in healthy volunteers (-1 +/- 11%, P = 0.28). CONCLUSIONS The results of the present study indicate that glibenclamide indeed affects microvascular blood flow. Glibenclamide may induce redistribution of the microvascular skin flow from nutritive flow to arteriovenous shunt flow in Type 2 diabetic patients. Therefore, closure of ATP-dependent potassium channels by glibenclamide possibly plays a role in the development of microangiopathy in Type 2 diabetic patients.
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Affiliation(s)
- E J Abbink
- Department of Pharmacology-Toxicology 233, University Medical Centre Nijmegen, 6500 HB Nijmegen, the Netherlands
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Farouque HMO, Worthley SG, Meredith IT, Skyrme-Jones RAP, Zhang MJ. Effect of ATP-sensitive potassium channel inhibition on resting coronary vascular responses in humans. Circ Res 2002; 90:231-6. [PMID: 11834717 DOI: 10.1161/hh0202.103713] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Experimental data suggest that vascular ATP-sensitive potassium (K(ATP)) channels regulate coronary blood flow (CBF), but their role in regulating human CBF is unclear. We sought to determine the contribution of K(ATP) channels to resting conduit vessel and microvascular function in the human coronary circulation. Twenty-five patients (19 male/6 female, aged 56 +/- 12 years) were recruited. Systemic and coronary hemodynamics were assessed in 20 patients before and after K(ATP) channel inhibition with graded intracoronary glibenclamide infusions (4, 16, and 40 microg/min), in an angiographically smooth or mildly stenosed coronary artery following successful elective percutaneous coronary intervention to another vessel. Coronary blood velocity was measured with a Doppler guidewire and CBF calculated. Adenosine-induced hyperemia was determined following bolus intracoronary adenosine injection (24 microg). Time control studies were undertaken in 5 patients. Compared with vehicle infusion (0.9% saline), glibenclamide reduced resting conduit vessel diameter from 2.5 +/- 0.1 to 2.3 +/- 0.1 mm (P<0.01), resting CBF by 17% (P=0.05), and resting CBF corrected for rate pressure-product by 18% (P=0.01) in a dose-dependent manner. A corresponding 24% increase in coronary vascular resistance was noted at the highest dose (P<0.01). No alteration to resting CBF was noted in the time control studies. Glibenclamide reduced peak adenosine-induced hyperemia (P=0.01) but did not alter coronary flow reserve. Plasma insulin increased from 5.6 +/- 1.2 to 7.6 +/- 1.3 mU/L (P=0.02); however, plasma glucose was unchanged. Vascular K(ATP) channels are involved in the maintenance of basal coronary tone but may not be essential to adenosine-induced coronary hyperemia in humans.
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Affiliation(s)
- H M Omar Farouque
- Centre for Heart and Chest Research, Monash Medical Centre and Monash University, Melbourne, Australia
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Abbink EJ, Pickkers P, Jansen van Rosendaal A, Lutterman JA, Tack CJ, Russel FGM, Smits P. Vascular effects of glibenclamide vs. glimepiride and metformin in Type 2 diabetic patients. Diabet Med 2002; 19:136-43. [PMID: 11874430 DOI: 10.1046/j.1464-5491.2002.00663.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS Glibenclamide attenuates the protective responses to opening of vascular ATP-sensitive potassium (K(ATP)) channels during ischaemia. Therefore, glibenclamide treatment of Type 2 diabetes mellitus may have hazardous cardiovascular effects when used under conditions of ischaemia. Glimepiride and metformin seem to lack such characteristics. Based on these data, we hypothesized that, in contrast to glibenclamide, chronic treatment of Type 2 diabetic patients with glimepiride or metformin will not impair the vasodilator function of K(ATP) opening in vivo. METHODS Two groups of 12 Type 2 diabetes mellitus patients participated in a double-blind randomized cross-over study consisting of two 8-week periods, in which treatment with orally administered glibenclamide (15 mg/day) was compared with either glimepiride or metformin (6 mg and 1500 mg/day, respectively). At the end of each treatment period, the increase in forearm blood flow (FBF, venous occlusion plethysmography) in response to intra-arterial administered diazoxide (K(ATP) opener), acetylcholine (endothelium-dependent vasodilator) and dipyridamole (adenosine-uptake blocker) and to forearm ischaemia was measured. RESULTS There were no significant differences in vasodilator responses to diazoxide, acetylcholine, dipyridamole and forearm ischaemia after glibenclamide compared with glimepiride and metformin. CONCLUSIONS Chronic treatment of Type 2 diabetes mellitus with glimepiride or metformin has similar effects on vascular K(ATP) channels compared with chronic glibenclamide treatment.
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Affiliation(s)
- E J Abbink
- Division of General Internal Medicine, Department of Medicine, University Medical Centre Nijmegen, Nijmegen, The Netherlands
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Reffelmann T, Klues HG, Hanrath P, Schwarz ER. Post-stenotic coronary blood flow at rest is not altered by therapeutic doses of the oral antidiabetic drug glibenclamide in patients with coronary artery disease. Heart 2002; 87:54-60. [PMID: 11751665 PMCID: PMC1766974 DOI: 10.1136/heart.87.1.54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE To investigate whether blood flow in normal and post-stenotic coronary arteries is altered by therapeutic doses of the sulfonylurea agent glibenclamide. PATIENTS 12 patients with a high grade stenosis of the left anterior descending coronary artery (n = 10) or left circumflex coronary artery (n = 2), and an angiographically normal corresponding left circumflex artery or left anterior descending artery, respectively. DESIGN Two Doppler ultrasound wires were positioned in the "normal" and post-stenotic artery for simultaneous measurements of coronary blood flow velocity under baseline conditions and after intravenous glibenclamide, 0.05 mg/kg body weight. Local coronary blood flow was calculated from the average peak velocity and the cross sectional area derived from quantitative coronary angiographic analysis. Coronary flow reserve was determined after intracoronary injection of 30 microg adenosine and 12 mg papaverine. RESULTS One hour after glibenclamide, serum insulin increased from (mean (SD)) 7.4 (2.0) to 44.8 (25.5) mU/l (p < 0.005), and C peptide from 1.4 (0.4) to 3.4 (1.2) ng/l (p = 0.005). In normal coronary arteries coronary flow reserve was 2.6 (0.4) after adenosine and 3.0 (0.4) after papaverine, while in post-stenotic arterial segments it was 1.2 (0.3) after adenosine (p = 0.005) and 1.3 (0.3) after papaverine (p = 0.005). There was no significant difference after glibenclamide. In non-stenotic arteries, average peak velocity (18.8 (5.2) cm/s) and calculated coronary blood flow (23.8 (10.7) ml/min) were not altered by glibenclamide (18.3 (5.2) cm/s and 22.8 (10.4) ml/min, respectively). In post-stenotic arteries, baseline average peak velocity was 13.3 (4.9) ml/min and coronary blood flow was 9.1 (3.0) ml/min, without significant change after glibenclamide (13.3 (5.2) cm/s, 9.0 (3.2) ml/min). CONCLUSIONS Glibenclamide, 0.05 mg/kg intravenously, is effective in increasing serum insulin, suggesting a K(ATP) channel blocking effect in pancreatic beta cells. It does not compromise coronary blood flow and vasodilatation in response to adenosine and papaverine in post-stenotic and angiographically normal coronary arteries at rest.
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Affiliation(s)
- T Reffelmann
- Medizinische Klinik I, University Hospital, Rheinisch-Westfälische Technische Hochschule (RWTH), Pauwelsstrasse 30, D-52057 Aachen, Germany.
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Spallarossa P, Schiavo M, Rossettin P, Cordone S, Olivotti L, Cordera R, Brunelli C. Sulfonylurea treatment of type 2 diabetic patients does not reduce the vasodilator response to ischemia. Diabetes Care 2001; 24:738-42. [PMID: 11315840 DOI: 10.2337/diacare.24.4.738] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Sulfonylureas block the activation of vascular potassium-dependent ATP channels and impair the vasodilating response to ischcmia in nondiabetic individuals, but it is not know whether this occurs in type 2 diabetic patients under chronic treatment with these drugs. Glimepiride, a new sulfonylurea, apparently has no cardiovascular interactions. The aim of our study was to compare the effect of the widely used compound glibenclamide, the pancreas-specific glimepiride, and diet treatment alone on brachial artery response to acute forearm ischemia. RESEARCH DESIGN AND METHODS Brachial artery examination was performed by a high-resolution ultrasound technique on 20 type 2 diabetic patients aged mean +/- SD) 67 +/- 2 years and on 18 nondiabetic patients matched for age, hypertension, and dislipidemia. Diabetic subjects underwent three separate evaluations at the end of each 8-week treatment period, during which they received glibenclamide, glimepiride, or diet alone according to crossover design. Scans were obtained before and after 4.5 min of forearm ischemia. Postischemic vasodilation and hyperemia were expressed as percent variations in vessel diameter and blood flow. RESULTS Postischemic vasodilation and hyperemia were, respectively, 5.42 +/- 0.90 and 331 +/- 38% during glibenclamide, 5.46 +/- 0.69 and 326 +/- 28% during glimepiride, and 5.17 +/- 0.64 and 357 +/- 35% during diet treatment (NS). These results were similar to those found in the nondiabetic patients (6.44 +/- 0.68 and 406 +/- 42%, NS). CONCLUSIONS In type 2 diabetic patients, the vasodilating response to forearm ischemia was the same whether patients were treated with diet treatment alone or with glibenclamide or glimepiride at blood glucose-lowering equipotent closes.
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Affiliation(s)
- P Spallarossa
- Department of Internal Medicine, University of Genova, Italy
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Monsuez JJ, Dufaux J, Vittecoq D, Vicaut E. Reduced reactive hyperemia in HIV-infected patients. J Acquir Immune Defic Syndr 2000; 25:434-42. [PMID: 11141243 DOI: 10.1097/00042560-200012150-00009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Given that several pathology-based studies reported some degree of coronary and arterial vasculopathy in HIV-infected patients, we investigated whether abnormal vascular reactivity may also be found in these patients. METHODS Vascular reactivity was assessed noninvasively using finger-skin blood-flow monitoring by laser-Doppler flow measurement in 10 HIV-infected-patients (mean CD4 T-cell count, 350+/-84 cells/mm3) with cardiac symptoms (previous myocardial infarction or left-ventricular dysfunction) and/or HIV-related protease inhibitor-induced hyperlipemia (group 1, symptomatic), 19 HIV-infected patients free of cardiac disease, hyperlipemia, and previous opportunistic infections (mean CD4 T-cell count, 333+/-175 cells/mm3; group 2, asymptomatic), and 19 healthy control subjects (group 3). Laser-Doppler flow was measured at baseline, during postocclusive hyperemic response following transient interruption of brachial blood flow (reactive hyperemia), during transcutaneous delivery of acetylcholine (Ach) using iontophoresis (endothelium-dependent dilation) and after sublingual nitroglycerin administration (endothelium-independent dilation). RESULTS During reactive hyperemia, the absolute increase in flow was found to be lower in asymptomatic HIV-infected patients than in controls (median values [25th-75th percentile]: asymptomatic: 300 [200-400]; versus controls: 600 [400-750] arbitrary units [AU]; p< or =.0001). This abnormality was more pronounced in symptomatic patients (100 [100-200]; p< or =.0001). There was also a reduced peak/baseline flow ratio (symptomatic: 1.14 [1.1-1.2]; asymptomatic: 1.40 [1.25-1.5]; versus controls: 1.83 [1.6-2.2]; p<.0001 for both comparisons) and a reduced hyperemic response, as assessed by the curve of area under the flow versus time from deflation to the end of the hyperemic response (symptomatic: 1850 [1100-2225]; asymptomatic: 6000 [2850-7950]; versus controls: 23,735 [16,000-31, 800] AU x sec; p<.0001 for both comparisons). Although there was no statistically significant difference in acetylcholine (Ach)-induced increases in flow between asymptomatic HIV patients and controls (peak/baseline flow ratio: 6 [4.4-10] versus 5.3 [4-8]; p =.47), a trend to lower values was seen in symptomatic patients (4.4 [1.2-5]; p =.06). Administration of 0.4 mg sublingual nitroglycerin resulted in increases in flow without statistically significant difference between patients and controls: peak/baseline flow ratio for symptomatic: 2.4 [1.9-2.7]; asymptomatic: 2.1 [1.75-2.34] versus controls: 1.97 [1.8-2.4]; p =.2 and.83, respectively). CONCLUSIONS Postischemic reactive hyperemia is reduced in HIV-infected patients. In addition, there was is trend for a reduced response to Ach only in those with cardiac disease and/or hyperlipemia.
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Affiliation(s)
- J J Monsuez
- Department of Internal Medicine, Hôpital Paul Brousse, Villejuif, France.
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Monsuez JJ, Dufaux J, Vittecoq D, Vicaut E. Reduced Reactive Hyperemia in HIV-Infected Patients. J Acquir Immune Defic Syndr 2000. [DOI: 10.1097/00126334-200012150-00009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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McAnulty GR, Robertshaw HJ, Hall GM. Anaesthetic management of patients with diabetes mellitus. Br J Anaesth 2000; 85:80-90. [PMID: 10927997 DOI: 10.1093/bja/85.1.80] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- G R McAnulty
- Department of Anaesthesia and Intensive Care Medicine, St George's Hospital Medical School, London, UK
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