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Nwokocha C, Palacios J, Ojukwu VE, Nna VU, Owu DU, Nwokocha M, McGrowder D, Orie NN. Oxidant-induced disruption of vascular K + channel function: implications for diabetic vasculopathy. Arch Physiol Biochem 2024; 130:361-372. [PMID: 35757993 DOI: 10.1080/13813455.2022.2090578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 06/07/2022] [Indexed: 11/02/2022]
Abstract
Diabetes in humans a chronic metabolic disorder characterised by hyperglycaemia, it is associated with an increased risk of cardiovascular disease, disruptions to metabolism and vascular functions. It is also linked to oxidative stress and its complications. Its role in vascular dysfunctions is generally reported without detailed impact on the molecular mechanisms. Potassium ion channel (K+ channels) are key regulators of vascular tone, and as membrane proteins, are modifiable by oxidant stress associated with diabetes. This review manuscript examined the impact of oxidant stress on vascular K+ channel functions in diabetes, its implication in vascular complications and metabolic and cardiovascular diseases.
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Affiliation(s)
| | - Javier Palacios
- Department of Pharmacy, Faculty of Health Sciences, Arturo Prat University, Iquique, Chile
| | - Victoria E Ojukwu
- Basic Medical Sciences, University of the West Indies, Mona, Kingston, Jamaica
| | - Victor Udo Nna
- Department of Physiology, College of Medical Sciences, University of Calabar, Calabar, Nigeria
| | - Daniel Udofia Owu
- Department of Physiology, College of Medical Sciences, University of Calabar, Calabar, Nigeria
| | - Magdalene Nwokocha
- Department of Pathology, Faculty of Medical Sciences, University of the West Indies, Mona, Kingston, Jamaica
| | - Donovan McGrowder
- Department of Pathology, Faculty of Medical Sciences, University of the West Indies, Mona, Kingston, Jamaica
| | - Nelson N Orie
- Centre of Metabolism and Inflammation, University College London, London, UK
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Razan MR, Akther F, Islam RA, Graham JL, Stanhope KL, Havel PJ, Rahimian R. 17β-Estradiol Treatment Improves Acetylcholine-Induced Relaxation of Mesenteric Arteries in Ovariectomized UC Davis Type 2 Diabetes Mellitus Rats in Prediabetic State. Front Physiol 2022; 13:900813. [PMID: 35784863 PMCID: PMC9248973 DOI: 10.3389/fphys.2022.900813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/23/2022] [Indexed: 11/18/2022] Open
Abstract
We recently reported sex differences in mesenteric arterial function of the UC Davis type-2 diabetes mellitus (UCD-T2DM) rats as early as the prediabetic state. We reported that mesenteric arteries (MA) from prediabetic male rats exhibited a greater impairment compared to that in prediabetic females. However, when females became diabetic, they exhibited a greater vascular dysfunction than males. Thus, the aim of this study was to investigate whether the female sex hormone, estrogen preserves mesenteric arterial vasorelaxation in UCD-T2DM female rats at an early prediabetic state. Age-matched female Sprague Dawley and prediabetic (PD) UCD-T2DM rats were ovariectomized (OVX) and subcutaneously implanted with either placebo or 17β-estradiol (E2, 1.5 mg) pellets for 45 days. We assessed the contribution of endothelium-derived relaxing factors (EDRF) to acetylcholine (ACh)-induced vasorelaxation, using pharmacological inhibitors. Responses to sodium nitroprusside (SNP) and phenylephrine (PE) were also measured. Additionally, metabolic parameters and expression of some targets associated with vascular and insulin signaling were determined. We demonstrated that the responses to ACh and SNP were severely impaired in the prediabetic state (PD OVX) rats, while E2 treatment restored vasorelaxation in the PD OVX + E2. Moreover, the responses to PE was significantly enhanced in MA of PD OVX groups, regardless of placebo or E2 treatment. Overall, our data suggest that 1) the impairment of ACh responses in PD OVX rats may, in part, result from the elevated contractile responses to PE, loss of contribution of endothelium-dependent hyperpolarization (EDH) to vasorelaxation, and a decreased sensitivity of MA to nitric oxide (NO), and 2) the basis for the protective effects of E2 may be partly attributed to the elevation of the NO contribution to vasorelaxation and its interaction with MA as well as potential improvement of insulin signaling. Here, we provide the first evidence of the role of E2 in protecting MA from early vascular dysfunction in prediabetic female rats.
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Affiliation(s)
- Md Rahatullah Razan
- Department of Physiology and Pharmacology, Thomas J. Long School of Pharmacy, University of the Pacific, Stockton, CA, United States
| | - Farjana Akther
- Department of Physiology and Pharmacology, Thomas J. Long School of Pharmacy, University of the Pacific, Stockton, CA, United States
| | - Rifat A. Islam
- Department of Physiology and Pharmacology, Thomas J. Long School of Pharmacy, University of the Pacific, Stockton, CA, United States
| | - James L. Graham
- Department of Molecular Biosciences, School of Veterinary Medicine, Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Kimber L. Stanhope
- Department of Molecular Biosciences, School of Veterinary Medicine, Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Peter J. Havel
- Department of Molecular Biosciences, School of Veterinary Medicine, Department of Nutrition, University of California, Davis, Davis, CA, United States
| | - Roshanak Rahimian
- Department of Physiology and Pharmacology, Thomas J. Long School of Pharmacy, University of the Pacific, Stockton, CA, United States
- *Correspondence: Roshanak Rahimian,
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Sonobe T, Tsuchimochi H, Maeda H, Pearson JT. Increased contribution of KCa channels to muscle contraction induced vascular and blood flow responses in sedentary and exercise trained ZFDM rats. J Physiol 2022; 600:2919-2938. [PMID: 35551673 DOI: 10.1113/jp282981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/04/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Microvascular dysfunction in type 2 diabetes impairs blood flow redistribution during exercise and limits the performance of skeletal muscle and may cause early fatigability. Endothelium-dependent hyperpolarization (EDH), which mediates vasodilation in resistance arteries is known to be depressed in animals with diabetes. Here we report that low-intensity exercise training in ZFDM rats increased KCa channel-derived component in the vasodilator responses to muscle contraction than in sedentary rats, partly due to the increase in KCNN3 expression. These results suggest that low-intensity exercise training improves blood flow redistribution in contracting skeletal muscle in metabolic disease with diabetes via upregulation of EDH. ABSTRACT In resistance arteries, endothelium-dependent hyperpolarization (EDH) mediated vasodilation is depressed in diabetes. We hypothesized that downregulation of KCa channel derived EDH reduces exercise-induced vasodilation and blood flow redistribution in diabetes. To test this hypothesis, we evaluated vascular function in response to hindlimb muscle contraction, and the contribution of KCa channels in anaesthetised ZFDM, metabolic disease rats with type 2 diabetes. We also tested whether exercise training ameliorated the vascular response. Using in vivo microangiography, the hindlimb vasculature was visualized before and after rhythmic muscle contraction (0.5 s tetanus every 3 sec, 20 times) evoked by sciatic nerve stimulation (40 Hz). Femoral blood flow of the contracting hindlimb was simultaneously measured by an ultrasonic flowmeter. The contribution of KCa channels was investigated in the presence and absence of apamin and charybdotoxin. We found that vascular and blood flow responses to muscle contraction were significantly impaired at the level of small artery segments in ZFDM fa/fa rats compared to its lean control fa/+ rats. The contribution of KCa channels was also smaller in fa/fa than in fa/+ rats. Low-intensity exercise training for 12 weeks in fa/fa rats demonstrated minor changes in the vascular and blood flow response to muscle contraction. However, KCa-derived component in the response to muscle contraction was much greater in exercise trained than in sedentary fa/fa rats. These data suggest that exercise training increases the contribution of KCa channels among endothelium-dependent vasodilatory mechanisms to maintain vascular and blood flow responses to muscle contraction in this metabolic disease rat model. Abstract figure legend Low-intensity exercise training in ZFDM, metabolic disease rats with type 2 diabetes increases KCa channel-derived component of endothelium-dependent hyperpolarization in the vascular and blood flow responses to skeletal muscle contraction than the responses in sedentary rats, partly due to upregulation of KCNN3 protein expression. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Takashi Sonobe
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - Hirotsugu Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - Hisashi Maeda
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan
| | - James T Pearson
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan.,Victoria Heart Institute and Monash Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Australia
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Shamsaldeen YA, Lione LA, Benham CD. Dysregulation of TRPV4, eNOS and caveolin-1 contribute to endothelial dysfunction in the streptozotocin rat model of diabetes. Eur J Pharmacol 2020; 888:173441. [PMID: 32810492 DOI: 10.1016/j.ejphar.2020.173441] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/30/2022]
Abstract
Endothelial dysfunction is a common complication in diabetes in which endothelium-dependent vasorelaxation is impaired. The aim of this study was to examine the involvement of the TRPV4 ion channel in type 1 diabetic endothelial dysfunction and the possible association of endothelial dysfunction with reduced expression of TRPV4, endothelial nitric oxide synthase (eNOS) and caveolin-1. Male Wistar rats (350-450 g) were injected with 65 mg/kg i.p. streptozotocin (STZ) or vehicle. Endothelial function was investigated in aortic rings and mesenteric arteries using organ bath and myograph, respectively. TRPV4 function was studied with fura-2 calcium imaging in endothelial cells cultured from aortas from control and STZ treated rats. TRPV4, caveolin-1 and eNOS expression was investigated in these cells using immunohistochemistry. STZ-treated diabetic rats showed significant endothelial dysfunction characterised by impaired muscarinic-induced vasorelaxation (aortic rings: STZ-diabetics: Emax = 29.6 ± 9.3%; control: Emax = 77.2 ± 2.5% P˂0.001), as well as significant impairment in TRPV4-induced vasorelaxation (aortic rings, 4αPDD STZ-diabetics: Emax = 56.0 ± 5.5%; control: Emax = 81.1 ± 2.1% P˂0.001). Furthermore, STZ-diabetic primary aortic endothelial cells showed a significant reduction in TRPV4-induced intracellular calcium elevation (P˂0.05) compared with the control group. This was associated with significantly lower expression of TRPV4, caveolin-1 and eNOS and this was reversed by insulin treatment of the endothelial cultures from STZ -diabetic rats. Taken together, these data are consistent with the hypothesis that signalling through TRPV4, caveolin-1, and eNOS is downregulated in STZ-diabetic aortic endothelial cells and restored by insulin treatment.
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Affiliation(s)
- Yousif A Shamsaldeen
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK; Department of Pharmacy, Kuwait Hospital, Sabah Alsalem, 44001, Kuwait.
| | - Lisa A Lione
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK
| | - Christopher D Benham
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK
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Mesenteric arterial dysfunction in the UC Davis Type 2 Diabetes Mellitus rat model is dependent on pre-diabetic versus diabetic status and is sexually dimorphic. Eur J Pharmacol 2020; 879:173089. [PMID: 32320701 DOI: 10.1016/j.ejphar.2020.173089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 03/21/2020] [Accepted: 03/25/2020] [Indexed: 01/27/2023]
Abstract
Previous reports suggest that diabetes may differentially affect the vascular beds of females and males. However, there is insufficient evidence to establish the timeline of the vascular dysfunction in diabetes, specifically in relation to sex. Here, we determined whether mesenteric arterial function is altered in UC Davis Type-2 Diabetes Mellitus (UCD-T2DM) rats and if this occurs as early as the pre-diabetic stage of the disease. Specifically, we investigated whether vascular dysfunction differs between pre-diabetic or diabetic status and if this varies by sex. We measured the responses to endothelium-dependent and -independent vasorelaxant as well as vasoconstrictor agents and explored the potential mechanisms involved in sex-specific development of arterial dysfunction in UCD-T2DM rats. In addition, indices of insulin sensitivity were assessed. We report the reduced insulin sensitivity in pre-diabetic males and diabetic females. Vascular relaxation to acetylcholine was impaired to a greater extent in mesenteric artery from males in the pre-diabetic stage than in their female counterparts. In contrast, the arteries from females with diabetes exhibited a greater impairment to acetylcholine compared with diabetic males. Additionally, the sensitivity of mesenteric artery to contractile agents in females, but not in males, after the onset of diabetes was increased. Our data suggest that the reduced insulin sensitivity through AKT may predispose vessels to injury in the pre-diabetic stage in males. On the other hand, reduced insulin sensitivity as well as enhanced responsiveness to contractile agents may predispose arteries to injury in the diabetic stage in females.
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Endothelium-Dependent Hyperpolarization (EDH) in Diabetes: Mechanistic Insights and Therapeutic Implications. Int J Mol Sci 2019; 20:ijms20153737. [PMID: 31370156 PMCID: PMC6695796 DOI: 10.3390/ijms20153737] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/25/2019] [Accepted: 07/30/2019] [Indexed: 02/07/2023] Open
Abstract
Diabetes mellitus is one of the major risk factors for cardiovascular disease and is an important health issue worldwide. Long-term diabetes causes endothelial dysfunction, which in turn leads to diabetic vascular complications. Endothelium-derived nitric oxide is a major vasodilator in large-size vessels, and the hyperpolarization of vascular smooth muscle cells mediated by the endothelium plays a central role in agonist-mediated and flow-mediated vasodilation in resistance-size vessels. Although the mechanisms underlying diabetic vascular complications are multifactorial and complex, impairment of endothelium-dependent hyperpolarization (EDH) of vascular smooth muscle cells would contribute at least partly to the initiation and progression of microvascular complications of diabetes. In this review, we present the current knowledge about the pathophysiology and underlying mechanisms of impaired EDH in diabetes in animals and humans. We also discuss potential therapeutic approaches aimed at the prevention and restoration of EDH in diabetes.
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Shamsaldeen YA, Ugur R, Benham CD, Lione LA. Diabetic dyslipidaemia is associated with alterations in eNOS, caveolin-1, and endothelial dysfunction in streptozotocin treated rats. Diabetes Metab Res Rev 2018; 34:e2995. [PMID: 29471582 DOI: 10.1002/dmrr.2995] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/19/2018] [Accepted: 02/05/2018] [Indexed: 12/30/2022]
Abstract
BACKGROUND Diabetes is a complex progressive disease characterized by chronic hyperglycaemia and dyslipidaemia associated with endothelial dysfunction. Oxidized LDL (Ox-LDL) is elevated in diabetes and may contribute to endothelial dysfunction. The aim of this study was to relate the serum levels of Ox-LDL with endothelial dysfunction in streptozotocin (STZ)-diabetic rats and to further explore the changes in endothelial nitric oxide synthase (eNOS) and caveolin-1 (CAV-1) expression in primary aortic endothelial cells. METHODS Diabetes was induced with a single intraperitoneal injection of STZ in male Wistar rats. During the hyperglycaemic diabetes state serum lipid markers, aortic relaxation and aortic endothelial cell eNOS and CAV-1 protein expressions were measured. RESULTS Elevated serum Ox-LDL (STZ 1486 ± 78.1 pg/mL vs control 732.6 ± 160.6 pg/mL, P < .05) was associated with hyperglycaemia (STZ 29 ± 0.9 mmol/L vs control: 7.2 ± 0.2 mmol/L, P < .001) and hypertriglyceridaemia (STZ 9.0 ± 1.5 mmol/L vs control: 3.0 ± 0.3 mmol/L, P < .01) in diabetic rats. A significant reduction was observed in STZ-diabetic aortic endothelial cell eNOS and CAV-1 of 40% and 30%, respectively, accompanied by a compromised STZ-diabetic carbachol-induced vasodilation (STZ 29.6 ± 9.3% vs control 77.2 ± 2.5%, P < .001). CONCLUSIONS The elevated serum Ox-LDL in hyperglycaemic STZ-diabetic rats may contribute to diabetic endothelial dysfunction, possibly through downregulation of endothelial CAV-1 and eNOS.
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Affiliation(s)
- Yousif A Shamsaldeen
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, UK
| | - Rosemary Ugur
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, UK
| | - Christopher D Benham
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, UK
| | - Lisa A Lione
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, UK
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Coleman HA, Tare M, Parkington HC. Nonlinear effects of potassium channel blockers on endothelium-dependent hyperpolarization. Acta Physiol (Oxf) 2017; 219:324-334. [PMID: 27639255 DOI: 10.1111/apha.12805] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/12/2016] [Accepted: 09/13/2016] [Indexed: 12/17/2022]
Abstract
In a number of published studies on endothelium-dependent hyperpolarization and relaxation, the results of the effects of K+ blockers have been difficult to interpret. When the effects of two blockers have been studied, often either blocker by itself had little effect, whereas the two blockers combined tended to abolish the responses. Explanations suggested in the literature include an unusual pharmacology of the K+ channels, and possible blocker binding interactions. In contrast, when we applied the same blockers to segments of small blood vessels under voltage clamp, the blockers reduced the endothelium-dependent K+ current in a linearly additive manner. Resolution of these contrasting results is important as endothelium-derived hyperpolarization (EDH) makes its greatest contribution to vasorelaxation in arterioles and small resistance arteries, where it can exert a significant role in tissue perfusion and blood pressure regulation. Furthermore, EDH is impaired in various diseases. Here, we consider why the voltage-clamp results differ from earlier free-running membrane potential and contractility studies. We fitted voltage-clamp-derived current-voltage relationships with mathematical functions and considered theoretically the effects of partial and total block of endothelium-derived K+ -currents on the membrane potential of small blood vessels. When the K+ -conductance was partially reduced, equivalent to applying a single blocker, the effect on EDH was small. Total block of the endothelium-dependent K+ conductance abolished the hyperpolarization, in agreement with various published studies. We conclude that nonlinear summation of the hyperpolarizing response evoked by endothelial stimulation can explain the variable effectiveness of individual K+ channel blockers on endothelium-dependent hyperpolarization and resulting relaxation.
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Affiliation(s)
- H. A. Coleman
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - M. Tare
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - H. C. Parkington
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
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Kahlberg N, Qin CX, Anthonisz J, Jap E, Ng HH, Jelinic M, Parry LJ, Kemp-Harper BK, Ritchie RH, Leo CH. Adverse vascular remodelling is more sensitive than endothelial dysfunction to hyperglycaemia in diabetic rat mesenteric arteries. Pharmacol Res 2016; 111:325-335. [DOI: 10.1016/j.phrs.2016.06.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/15/2016] [Accepted: 06/26/2016] [Indexed: 11/26/2022]
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Boydens C, Pauwels B, Vanden Daele L, Van de Voorde J. Protective effect of resveratrol and quercetin on in vitro-induced diabetic mouse corpus cavernosum. Cardiovasc Diabetol 2016; 15:46. [PMID: 26993793 PMCID: PMC4797116 DOI: 10.1186/s12933-016-0366-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 03/11/2016] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Hyperglycemia and increased levels of methylglyoxal (MGO) can trigger the development of vascular complications in diabetes. Resveratrol and quercetin are red wine polyphenols with known beneficial cardiovascular properties, including an antioxidant capacity. This study evaluated whether resveratrol and/or quercetin could prevent in vitro-induced diabetic changes in neurogenic and vascular relaxant responses of mouse arteries and corpora cavernosa. METHODS Isometric tension of isolated aorta, mesenteric arteries and corpora cavernosa was measured using organ bath systems. Diabetic conditions were mimicked in vitro by co-incubating the tissues for 2 h with high glucose (HG, 30 mM) and MGO (120 µM). RESULTS The presence of HG and MGO significantly blunted acetylcholine (Ach)-induced relaxations in corpora cavernosa and mesenteric arteries but not in aorta. Electrical field stimulated (EFS) responses of corpora cavernosa were also significantly inhibited by these diabetic conditions. In corpora cavernosa 2 h co-incubation with resveratrol (30 µM) or quercetin (30 µM) significantly attenuated HG and MGO-induced deficits in Ach- and EFS-responses. CONCLUSIONS Our study demonstrates that in mouse arteries, HG and MGO rather affect endothelium derived hyperpolarizing factor-mediated than nitric oxide (NO)-mediated relaxations. In corpora cavernosa HG and MGO interfere with NO release. Resveratrol and quercetin protect mouse corpora cavernosa from diabetic-induced damage to NO-mediated relaxant responses. This might rely on their antioxidant capacity.
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Affiliation(s)
- Charlotte Boydens
- Department of Pharmacology, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Bart Pauwels
- Department of Pharmacology, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Laura Vanden Daele
- Department of Pharmacology, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Johan Van de Voorde
- Department of Pharmacology, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
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Salheen SM, Panchapakesan U, Pollock CA, Woodman OL. The Dipeptidyl Peptidase-4 Inhibitor Linagliptin Preserves Endothelial Function in Mesenteric Arteries from Type 1 Diabetic Rats without Decreasing Plasma Glucose. PLoS One 2015; 10:e0143941. [PMID: 26618855 PMCID: PMC4664283 DOI: 10.1371/journal.pone.0143941] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/11/2015] [Indexed: 12/15/2022] Open
Abstract
The aim of the study was to investigate the effect of the DPP-4 inhibitor linagliptin on the mechanism(s) of endothelium-dependent relaxation in mesenteric arteries from STZ-induced diabetic rats. Both normal and diabetic animals received linagliptin (2 mg/kg) daily by oral gavage for a period of 4 weeks. To measure superoxide generation in mesenteric arteries, lucigenin-enhanced chemiluminescence was used. ACh-induced relaxation of mesenteric arteries was assessed using organ bath techniques and Western blotting was used to investigate protein expression. Pharmacological tools (1μM TRAM-34, 1μM apamin, 100 nM Ibtx, 100 μM L-NNA, 10 μM ODQ) were used to distinguish between NO and EDH-mediated relaxation. Linagliptin did not affect plasma glucose, but did decrease vascular superoxide levels. Diabetes reduced responses to ACh but did not affect endothelium-independent responses to SNP. Linagliptin improved endothelial function indicated by a significant increase in responses to ACh. Diabetes impaired the contribution of both nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) to endothelium-dependent relaxation and linagliptin treatment significantly enhanced the contribution of both relaxing factors. Western blotting demonstrated that diabetes also increased expression of Nox2 and decreased expression and dimerization of endothelial NO synthase, effects that were reversed by linagliptin. These findings demonstrate treatment of type 1 diabetic rats with linagliptin significantly reduced vascular superoxide levels and preserved both NO and EDH-mediated relaxation indicating that linagliptin can improve endothelial function in diabetes independently of any glucose lowering activity.
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Affiliation(s)
- Salheen M Salheen
- School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Usha Panchapakesan
- Kolling Institute of Medical Research, Royal North Shore Hospital, University of Sydney, St Leonards, New South Wales, Australia
| | - Carol A Pollock
- Kolling Institute of Medical Research, Royal North Shore Hospital, University of Sydney, St Leonards, New South Wales, Australia
| | - Owen L Woodman
- School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia
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Impaired endothelial calcium signaling is responsible for the defective dilation of mesenteric resistance arteries from db/db mice to acetylcholine. Eur J Pharmacol 2015; 767:17-23. [DOI: 10.1016/j.ejphar.2015.09.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/24/2015] [Accepted: 09/24/2015] [Indexed: 11/22/2022]
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13
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Han X, Shaligram S, Zhang R, Anderson L, Rahimian R. Sex-specific vascular responses of the rat aorta: effects of moderate term (intermediate stage) streptozotocin-induced diabetes. Can J Physiol Pharmacol 2015; 94:408-15. [PMID: 26845285 DOI: 10.1139/cjpp-2015-0272] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hyperglycemia affects male and female vascular beds differently. We have previously shown that 1 week after the induction of diabetes with streptozotocin (STZ), male and female rats exhibit differences in aortic endothelial function. To examine this phenomenon further, aortic responses were studied in male and female rats 8 weeks after the induction of diabetes (intermediate stage). Endothelium-dependent vasodilation (EDV) to acetylcholine (ACh) was measured in phenylephrine (PE) pre-contracted rat aortic rings. Concentration response curves to PE were generated before and after L-NAME, a nitric oxide synthase (NOS) inhibitor. Furthermore, mRNA expression of endothelial nitric oxide synthase (eNOS) and NADPH oxidase subunit (Nox1) were determined. At 8 weeks, diabetes impaired EDV to a greater extent in female than male aortae. Furthermore, the responsiveness to PE was significantly enhanced only in female diabetic rats, and basal NO, as indicated by the potentiation of the response to PE after L-NAME, was reduced in female diabetic rat aortae to the same levels as in males. In addition, eNOS mRNA expression was decreased, while the Nox1 expression was significantly enhanced in diabetic female rats. These results suggest that aortic function in female diabetic rats after 8 weeks exhibits a more prominent impairment and that NO may be involved.
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Affiliation(s)
- Xiaoyuan Han
- a Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211, USA
| | - Sonali Shaligram
- a Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211, USA
| | - Rui Zhang
- a Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211, USA
| | - Leigh Anderson
- b Department of Biomedical Sciences, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, CA 94115, USA
| | - Roshanak Rahimian
- a Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211, USA
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Sonobe T, Tsuchimochi H, Schwenke DO, Pearson JT, Shirai M. Treadmill running improves hindlimb arteriolar endothelial function in type 1 diabetic mice as visualized by X-ray microangiography. Cardiovasc Diabetol 2015; 14:51. [PMID: 25964060 PMCID: PMC4430879 DOI: 10.1186/s12933-015-0217-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 04/18/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Vascular function is impaired in patients with diabetes, however diabetic vascular dysfunction is ameliorated by exercise training. We aimed to clarify which hindlimb arterial segments are affected by treadmill running in the hindlimbs of streptozocin-induced type 1 diabetic mice in vivo. METHODS Mice were divided into 3 groups; healthy control, diabetic control, and diabetic-running groups. The exercise regimen was performed by treadmill level running mice for 60 min/day, for 4 weeks. Thereafter, we examined the vascular response to systemic acetylcholine administration in the left hindlimb of anesthetized-ventilated mice using either 1) X-ray microangiography to visualize the arteries or 2) ultrasonic flowmetry to record the femoral arterial blood flow. RESULTS X-ray imaging clearly visualized the hindlimb arterial network (~70-250 μm diameter). The vasodilator response to acetylcholine was significantly attenuated locally in the arterioles <100 μm diameter in the diabetic group of mice compared to the control group of mice. Post-acetylcholine administration, all groups showed an increase in hindlimb vascular conductance, but the diabetic mice showed the smallest increase. Overall, compared to the diabetic mice, the treadmill-running mice exhibited a significant enhancement of the vasodilator response within the arterioles with diabetes-induced vasodilator dysfunction. CONCLUSIONS Diabetes impaired acetylcholine-induced vasodilator function locally in the arteries <100 μm diameter and decreased hindlimb vascular conductance responded to acetylcholine, while regular treadmill running significantly ameliorated the impaired vasodilator function, and enhanced the decreased conductance in the diabetic mice.
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Affiliation(s)
- Takashi Sonobe
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan.
| | - Hirotsugu Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan.
| | - Daryl O Schwenke
- Department of Physiology-Heart Otago, University of Otago, Dunedin, New Zealand.
| | - James T Pearson
- Department of Physiology, and Monash Biomedical Imaging Facility, Monash University, Melbourne, Australia. .,Australian Synchrotron, Clayton, Australia.
| | - Mikiyasu Shirai
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka, Japan.
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Kavoussi PK, Heberlein K, Straub AC, Lowe GJ, Oliver JL, Smith RP, Steers WD, Annex BH, Isakson BE, Lysiak JJ. Recombinant PAI-1 therapy restores myoendothelial junctions and erectile function in PAI-1-deficient mice. Andrologia 2015; 47:1147-52. [PMID: 25557984 DOI: 10.1111/and.12395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2014] [Indexed: 11/30/2022] Open
Abstract
Myoendothelial junctions are specialised projections of cell : cell contact through the internal elastic lamina between endothelial cells and vascular smooth muscle cells. These junctions allow for endothelial cells and vascular smooth muscle cells to make direct membrane apposition and are involved in cell : cell communication. In this study, we evaluated for the presence of myoendothelial junctions in murine corporal tissue and used plasminogen activator inhibitor (PAI)-1-deficient mice, which lack myoendothelial junctions, to determine whether myoendothelial junctions affect erectile function. Transmission electron microscopy demonstrated the presence of myoendothelial junctions in the corporal tissue of wild-type mice and confirmed the decreased junction numbers in the tissue of PAI-1(-/-) mice. A potential role for myoendothelial junctions in tumescence was established; in that, PAI-1(-/-) mice demonstrated a significantly longer time to achieve maximal intracavernous pressure. Treatment of PAI-1(-/-) mice with recombinant PAI-1 restored the number of myoendothelial junctions in the corporal tissue and also induced a significant decrease in time to maximal corporal pressures. Myoendothelial junctions were similarly identified in the human corporal tissue. These results suggest a critical role for myoendothelial junctions in erectile pathophysiology and therapies aimed at restoring myoendothelial junction numbers in the corporal tissue may provide a novel therapy for erectile dysfunction.
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Affiliation(s)
- P K Kavoussi
- Department of Urology, University of Virginia Health System, Charlottesville, VA, USA
| | - K Heberlein
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, USA
| | - A C Straub
- Robert M. Berne Cardiovascular Research Center, University of Virginia Health System, Charlottesville, VA, USA
| | - G J Lowe
- Department of Urology, University of Virginia Health System, Charlottesville, VA, USA
| | - J L Oliver
- Department of Urology, University of Virginia Health System, Charlottesville, VA, USA
| | - R P Smith
- Department of Urology, University of Virginia Health System, Charlottesville, VA, USA
| | - W D Steers
- Department of Urology, University of Virginia Health System, Charlottesville, VA, USA
| | - B H Annex
- Robert M. Berne Cardiovascular Research Center, University of Virginia Health System, Charlottesville, VA, USA
| | - B E Isakson
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia Health System, Charlottesville, VA, USA
| | - J J Lysiak
- Department of Urology, University of Virginia Health System, Charlottesville, VA, USA
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16
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Cai Y, Manio MM, Leung GP, Xu A, Tang EH, Vanhoutte PM. Thyroid hormone affects both endothelial and vascular smooth muscle cells in rat arteries. Eur J Pharmacol 2015; 747:18-28. [DOI: 10.1016/j.ejphar.2014.11.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 11/26/2014] [Accepted: 11/28/2014] [Indexed: 02/04/2023]
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Schach C, Resch M, Schmid PM, Riegger GA, Endemann DH. Type 2 diabetes: increased expression and contribution of IKCa channels to vasodilation in small mesenteric arteries of ZDF rats. Am J Physiol Heart Circ Physiol 2014; 307:H1093-102. [DOI: 10.1152/ajpheart.00240.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Impaired endothelial function, which is dysregulated in diabetes, also precedes hypertension. We hypothesized that in Type 2 diabetes, the impaired endothelium-dependent relaxation is due to a loss of endothelium-derived hyperpolarization (EDH) that is regulated by impaired ion channel function. Zucker diabetic fatty (ZDF), Zucker heterozygote, and homozygote lean control rats were used as the experimental models in our study. Third-order mesenteric arteries were dissected and mounted on a pressure myograph; mRNA was quantified by RT-PCR and channel proteins by Western blotting. Under nitric oxide (NO) synthase and cyclooxygenase inhibition, endothelial stimulation with ACh fully relaxes control but not diabetic arteries. In contrast, when small-conductance calcium-activated potassium (KCa) channels and intermediate- and large-conductance KCa (I/BKCa) are inhibited with apamin and charybdotoxin, NO is able to compensate for ACh-induced relaxation in control but not in diabetic vessels. After replacement of charybdotoxin with 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34; IKCa inhibitor), ACh-induced relaxation in diabetic animals is attenuated. Specific inhibition with TRAM-34 or charybdotoxin attenuates ACh relaxation in diabetes. Stimulation with 1-ethyl-2-benzimidazolinone (IKCa activator) shows a reduced relaxation in diabetes. Activation of BKCa with 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one NS619 leads to similar relaxations of control and diabetic arteries. RT-PCR and Western blot analysis demonstrate elevated mRNA and protein expression levels of IKCa in diabetes. Our results suggest that the compensatory effect of NO and EDH-associated, endothelium-dependent relaxation is reduced in ZDF rats. Specific blockade of IKCa with TRAM-34 reduces NO and EDH-type relaxation in diabetic rats, indicating an elevated contribution of IKCa in diabetic small mesenteric artery relaxation. This finding correlates with increased IKCa mRNA and protein expression in this vessel.
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Affiliation(s)
- Christian Schach
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Markus Resch
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Peter M. Schmid
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Guenter A. Riegger
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
| | - Dierk H. Endemann
- Department of Cardiology, University Hospital Regensburg, Regensburg, Germany
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Endothelial arginine resynthesis contributes to the maintenance of vasomotor function in male diabetic mice. PLoS One 2014; 9:e102264. [PMID: 25033204 PMCID: PMC4102520 DOI: 10.1371/journal.pone.0102264] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 06/16/2014] [Indexed: 02/06/2023] Open
Abstract
Aim Argininosuccinate synthetase (ASS) is essential for recycling L-citrulline, the by-product of NO synthase (NOS), to the NOS substrate L-arginine. Here, we assessed whether disturbed arginine resynthesis modulates endothelium-dependent vasodilatation in normal and diabetic male mice. Methods and Results Endothelium-selective Ass-deficient mice (Assfl/fl/Tie2Cretg/− = Ass-KOTie2) were generated by crossing Assfl/fl mice ( = control) with Tie2Cre mice. Gene ablation in endothelial cells was confirmed by immunohistochemistry. Blood pressure (MAP) was recorded in 34-week-old male mice. Vasomotor responses were studied in isolated saphenous arteries of 12- and 34-week-old Ass-KOTie2 and control animals. At the age of 10 weeks, diabetes was induced in control and Ass-KOTie2 mice by streptozotocin injections. Vasomotor responses of diabetic animals were studied 10 weeks later. MAP was similar in control and Ass-KOTie2 mice. Depletion of circulating L-arginine by arginase 1 infusion or inhibition of NOS activity with L-NAME resulted in an increased MAP (10 and 30 mmHg, respectively) in control and Ass-KOTie2 mice. Optimal arterial diameter, contractile responses to phenylephrine, and relaxing responses to acetylcholine and sodium nitroprusside were similar in healthy control and Ass-KOTie2 mice. However, in diabetic Ass-KOTie2 mice, relaxation responses to acetylcholine and endothelium-derived NO (EDNO) were significantly reduced when compared to diabetic control mice. Conclusions Absence of endothelial citrulline recycling to arginine did not affect blood pressure and systemic arterial vasomotor responses in healthy mice. EDNO-mediated vasodilatation was significantly more impaired in diabetic Ass-KOTie2 than in control mice demonstrating that endothelial arginine recycling becomes a limiting endothelial function in diabetes.
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Badavi M, Abedi HA, Sarkaki AR, Dianat M. Co-administration of Grape Seed Extract and Exercise Training Improves Endothelial Dysfunction of Coronary Vascular Bed of STZ-Induced Diabetic Rats. IRANIAN RED CRESCENT MEDICAL JOURNAL 2013; 15:e7624. [PMID: 24693368 PMCID: PMC3950780 DOI: 10.5812/ircmj.7624] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 02/02/2013] [Accepted: 07/15/2013] [Indexed: 02/07/2023]
Abstract
Background One of the known complications of diabetes mellitus is vascular dysfunction. Inability of the coronary vascular response to cardiac hyperactivity might cause a higher incidence of ischemic heart disease in diabetic subjects. It has been indicated that regular exercise training and antioxidants could prevent diabetic cardiovascular problems enhanced by vascular damage. Objectives The aim of this study was to determine the effects of grape seed extract (as antioxidant), with and without exercise training on coronary vascular function in streptozotocin induced diabetic rats. Materials and Methods Fifty male Wistar rats weighing 200 – 232 grams were randomly divided into five groups of 10 rats each: sedentary control, sedentary diabetic, trained diabetic, grape seed extract (200 mg/kg) treated sedentary diabetic and, grape seed extract treated trained diabetic. Diabetes was induced by one intraperitoneal injection of streptozotocin. After eight weeks, coronary vascular responses to vasoactive agents were determined. Results The endothelium dependent vasorelaxation to acetylcholine was reduced significantly in diabetic animals; exercise training or grape seed extract administration partially improves this response. However, exercise training in combination with grape seed extract restores endothelial function completely. The endothelium independent vasorelaxation to sodium nitroprusside was improved by combination of exercise training and grape seed extract. On the other hand, the basal perfusion pressure and vasoconstrictive response to phenylephrine did not change significantly. Conclusions The data indicated that co-administration of grape seed extract and exercise training had more significant effects than exercise training or grape seed extract alone; this may constitute a convenient and inexpensive therapeutic approach to diabetic vascular complications.
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Affiliation(s)
- Mohammad Badavi
- Physiology Research Center, Physiology Department, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
| | - Hassan Ali Abedi
- Physiology Department, Faculty of Medicine, Jahrom University of Medical Sciences, Jahrom, IR Iran
- Corresponding Author: Hassan Ali Abedi, Physiology Department, Faculty of Medicine, Jahrom University of Medical Sciences, Jahrom, IR Iran. Tel: +98-7913340405, Fax: +98-7914440072, E-mail:
| | - Ali Reza Sarkaki
- Physiology Research Center, Physiology Department, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
| | - Mahin Dianat
- Physiology Research Center, Physiology Department, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
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Abstract
Endothelium-derived hyperpolarizing factors (EDHFs) regulate vascular tone by contributing to the vasorelaxations to shear stress and endothelial agonists such as bradykinin and acetylcholine. 15(S)-Hydroxy-11,12-epoxyeicosatrienoic acid (15-H-11,12-EETA) and 11(R),12(S),15(S)-trihydroxyeicosatrienoic acid (11,12,15-THETA) are endothelial metabolites of the 15-lipoxygenase (15-LO) pathway of arachidonic acid metabolism and are EDHFs. 11,12,15-THETA activates small conductance, calcium-activated potassium channels on smooth muscle cells causing membrane hyperpolarization, and relaxation. Expression levels of 15-LO in the endothelium regulate the activity of the 15-LO/15-H-11,12-EETA/11,12,15-THETA pathway and its contribution to vascular tone. Regulation of its expression is by transcriptional, translational, and epigenetic mechanisms. Hypoxia, hypercholesterolemia, atherosclerosis, anemia, estrogen, interleukins, and possibly other hormones increase 15-LO expression. An increase in 15-LO results in increased synthesis of 15-H-11,12-EETA and 11,12,15-THETA, increased membrane hyperpolarization, and enhanced contribution to relaxation by endothelial agonists. Thus, the 15-LO pathway represents the first example of an inducible EDHF. In addition to 15-LO metabolites, a number of chemicals have been identified as EDHFs and their contributions to vascular tone vary with species and vascular bed. The reason for multiple EDHFs has evaded explanation. However, EDHF functioning as constitutive EDHFs or inducible EDHFs may explain the need for chemically and biochemically distinct pathways for EDHF activity and the variation in EDHFs between species and vascular beds. This new EDHF classification provides a framework for understanding EDHF activity in physiological and pathological conditions.
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21
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Naser N, Januszewski AS, Brown BE, Jenkins AJ, Hill MA, Murphy TV. Advanced glycation end products acutely impair ca(2+) signaling in bovine aortic endothelial cells. Front Physiol 2013; 4:38. [PMID: 23483845 PMCID: PMC3593230 DOI: 10.3389/fphys.2013.00038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 02/13/2013] [Indexed: 01/16/2023] Open
Abstract
Post-translational modification of proteins in diabetes, including formation of advanced glycation end products (AGEs) are believed to contribute to vascular dysfunction and disease. Impaired function of the endothelium is an early indicator of vascular dysfunction in diabetes and as many endothelial cell processes are dependent upon intracellular [Ca2+] and Ca2+ signaling, the aim of this study was to examine the acute effects of AGEs on Ca2+ signaling in bovine aortic endothelial cells (BAEC). Ca2+ signaling was studied using the fluorescent indicator dye Fura-2-AM. AGEs were generated by incubating bovine serum albumin with 0–250 mM glucose or glucose-6-phosphate for 0–120 days at 37°C. Under all conditions, the main AGE species generated was carboxymethyl lysine (CML) as assayed using both gas-liquid chromatograph-mass spectroscopy and high-performance liquid chromatography. In Ca2+-replete solution, exposure of BAEC to AGEs for 5 min caused an elevation in basal [Ca2+] and attenuated the increase in intracellular [Ca2+] caused by ATP (100 μM). In the absence of extracellular Ca2+, exposure of BAEC to AGEs for 5 min caused an elevation in basal [Ca2+] and attenuated subsequent intracellular Ca2+ release caused by ATP, thapsigargin (0.1 μM), and ionomycin (3 μM), but AGEs did not affect extracellular Ca2+ entry induced by the re-addition of Ca2+ to the bathing solution in the presence of any of these agents. The anti-oxidant α-lipoic acid (2 μM) and NAD(P)H oxidase inhibitors apocynin (500 μM) and diphenyleneiodonium (1 μM) abolished these effects of AGEs on BAECs, as did the IP3 receptor antagonist xestospongin C (1 μM). In summary, AGEs caused an acute depletion of Ca2+ from the intracellular store in BAECs, such that the Ca2+ signal stimulated by the subsequent application other agents acting upon this store is reduced. The mechanism may involve generation of reactive oxygen species from NAD(P)H oxidase and possible activation of the IP3 receptor.
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Affiliation(s)
- Nadim Naser
- Department of Physiology, School of Medical Sciences, University of New South Wales Sydney, NSW, Australia
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22
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Gokina NI, Bonev AD, Gokin AP, Goloman G. Role of impaired endothelial cell Ca(2+) signaling in uteroplacental vascular dysfunction during diabetic rat pregnancy. Am J Physiol Heart Circ Physiol 2013; 304:H935-45. [PMID: 23376827 DOI: 10.1152/ajpheart.00513.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diabetes mellitus in pregnancy is associated with impaired endothelium-mediated dilatation of maternal arteries, although the underlying cellular mechanisms remain unknown. In this study, we hypothesized that diabetes during rat gestation attenuates agonist-induced uterine vasodilation through reduced endothelial cell (EC) Ca(2+) elevations and impaired smooth muscle cell (SMC) hyperpolarization and SMC intracellular Ca(2+) concentration ([Ca(2+)]i) responses. Diabetes was induced by an injection of streptozotocin to second-day pregnant rats and confirmed by the development of maternal hyperglycemia. Control rats were injected with a citrate buffer. Fura-2-based measurements of SMC [Ca(2+)]i or microelectrode recordings of SMC membrane potential were performed concurrently with dilator responses to ACh in uteroplacental arteries from control and diabetic pregnant rats. Basal levels of EC [Ca(2+)]i and ACh-induced EC [Ca(2+)]i elevations in pressurized vessels and small EC sheets were studied as well. Diabetes reduced ACh-induced vasodilation due to a markedly impaired EDHF-mediated response. Diminished vasodilation to ACh was associated with attenuated SMC hyperpolarization and [Ca(2+)]i responses. Basal levels of EC [Ca(2+)]i and ACh-induced EC [Ca(2+)]i elevations were significantly reduced by diabetes. In conclusion, these data demonstrate that reduced endothelium-mediated hyperpolarization contributes to attenuated uteroplacental vasodilation and SMC [Ca(2+)]i responses to ACh in diabetic pregnancy. Impaired endothelial Ca(2+) signaling is in part responsible for endothelial dysfunction in the uterine resistance vasculature of diabetic rats. Pharmacological improvement of EC Ca(2+) handling may provide an important strategy for the restoration of endothelial function and enhancement of maternal blood flow in human pregnancies complicated by diabetes.
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Affiliation(s)
- Natalia I Gokina
- Department of Obstetrics, Gynecology, and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, VT 05405, USA.
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Delbin MA, Davel APC, Couto GK, de Araújo GG, Rossoni LV, Antunes E, Zanesco A. Interaction between advanced glycation end products formation and vascular responses in femoral and coronary arteries from exercised diabetic rats. PLoS One 2012; 7:e53318. [PMID: 23285277 PMCID: PMC3532341 DOI: 10.1371/journal.pone.0053318] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 11/29/2012] [Indexed: 01/28/2023] Open
Abstract
Background The majority of studies have investigated the effect of exercise training (TR) on vascular responses in diabetic animals (DB), but none evaluated nitric oxide (NO) and advanced glycation end products (AGEs) formation associated with oxidant and antioxidant activities in femoral and coronary arteries from trained diabetic rats. Our hypothesis was that 8-week TR would alter AGEs levels in type 1 diabetic rats ameliorating vascular responsiveness. Methodology/Principal Findings Male Wistar rats were divided into control sedentary (C/SD), sedentary diabetic (SD/DB), and trained diabetic (TR/DB). DB was induced by streptozotocin (i.p.: 60 mg/kg). TR was performed for 60 min per day, 5 days/week, during 8 weeks. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), phenylephrine (PHE) and tromboxane analog (U46619) were obtained. The protein expressions of eNOS, receptor for AGEs (RAGE), Cu/Zn-SOD and Mn-SOD were analyzed. Tissues NO production and reactive oxygen species (ROS) generation were evaluated. Plasma nitrate/nitrite (NOx−), superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS) and Nε-(carboxymethyl) lysine (CML, AGE biomarker). A rightward shift in the concentration-response curves to ACh was observed in femoral and coronary arteries from SD/DB that was accompanied by an increase in TBARS and CML levels. Decreased in the eNOS expression, tissues NO production and NOx− levels were associated with increased ROS generation. A positive interaction between the beneficial effect of TR on the relaxing responses to ACh and the reduction in TBARS and CML levels were observed without changing in antioxidant activities. The eNOS protein expression, tissues NO production and ROS generation were fully re-established in TR/DB, but plasma NOx− levels were partially restored. Conclusion Shear stress induced by TR fully restores the eNOS/NO pathway in both preparations from non-treated diabetic rats, however, a massive production of AGEs still affecting relaxing responses possibly involving other endothelium-dependent vasodilator agents, mainly in coronary artery.
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MESH Headings
- Animals
- Antioxidants/metabolism
- Antioxidants/pharmacology
- Coronary Vessels/drug effects
- Coronary Vessels/metabolism
- Coronary Vessels/physiopathology
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Experimental/therapy
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/physiopathology
- Endothelium-Dependent Relaxing Factors/metabolism
- Endothelium-Dependent Relaxing Factors/pharmacology
- Femoral Artery/drug effects
- Femoral Artery/metabolism
- Femoral Artery/physiopathology
- Glycation End Products, Advanced/metabolism
- Glycation End Products, Advanced/pharmacology
- Male
- Physical Conditioning, Animal
- Rats
- Rats, Wistar
- Reactive Oxygen Species/metabolism
- Reactive Oxygen Species/pharmacology
- Streptozocin
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Affiliation(s)
- Maria A. Delbin
- Department of Physical Education, Institute of Bioscience, University of São Paulo State (UNESP), Rio Claro, São Paulo, Brazil
| | - Ana Paula C. Davel
- Department of Anatomy, Cellular Biology, Physiology and Biophysics, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Gisele Kruger Couto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, São Paulo, Brazil
| | - Gustavo G. de Araújo
- Department of Physical Education, Institute of Bioscience, University of São Paulo State (UNESP), Rio Claro, São Paulo, Brazil
| | - Luciana Venturini Rossoni
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, São Paulo, Brazil
| | - Edson Antunes
- Department of Pharmacology, Faculty of Medical Sciences, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Angelina Zanesco
- Department of Physical Education, Institute of Bioscience, University of São Paulo State (UNESP), Rio Claro, São Paulo, Brazil
- * E-mail:
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Zhang R, Thor D, Han X, Anderson L, Rahimian R. Sex differences in mesenteric endothelial function of streptozotocin-induced diabetic rats: a shift in the relative importance of EDRFs. Am J Physiol Heart Circ Physiol 2012; 303:H1183-98. [PMID: 22982780 DOI: 10.1152/ajpheart.00327.2012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Several studies suggest that diabetes affects male and female vascular beds differently. However, the mechanisms underlying the interaction of sex and diabetes remain to be investigated. This study investigates whether there are 1) sex differences in the development of abnormal vascular responses and 2) changes in the relative contributions of endothelium-derived relaxing factors in modulating vascular reactivity of mesenteric arteries taken from streptozotocin (STZ)-induced diabetic rats at early and intermediate stages of the disease (1 and 8 wk, respectively). We also investigated the mesenteric expression of the mRNAs for endothelial nitric oxide (NO) synthase (eNOS) and NADPH oxidase (Nox) in STZ-induced diabetes in both sexes. Vascular responses to acetylcholine (ACh) in mesenteric arterial rings precontracted with phenylephrine were measured before and after pretreatment with indomethacin (cyclooxygenase inhibitor), N(ω)-nitro-L-arginine methyl ester (NOS inhibitor), or barium chloride (K(ir) blocker) plus ouabain (Na(+)-K(+)-ATPase inhibitor). We demonstrated that ACh-induced relaxations were significantly impaired in mesenteric arteries from both male and female diabetic rats at 1 and 8 wk. However, at 8 wk the extent of impairment was significantly greater in diabetic females than diabetic males. Our data also showed that in females, the levels of eNOS, Nox2, and Nox4 mRNA expression and the relative importance of NO to the regulation of vascular reactivity were substantially enhanced, whereas the importance of endothelium-derived hyperpolarizing factor (EDHF) was significantly reduced at both 1 and 8 wk after the induction of diabetes. This study reveals the predisposition of female rat mesenteric arteries to vascular injury after the induction of diabetes may be due to a shift away from a putative EDHF, initially the major vasodilatory factor, toward a greater reliance on NO.
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Affiliation(s)
- Rui Zhang
- Department of Physiology and Pharmacology, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, USA
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Correlations between Endothelial Functions and ROS Detection in Diabetic Microvascular Wall: Early and Late Ascorbic Acid Supplementation. Int J Vasc Med 2012; 2012:709695. [PMID: 22690337 PMCID: PMC3368388 DOI: 10.1155/2012/709695] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/22/2012] [Accepted: 02/29/2012] [Indexed: 02/07/2023] Open
Abstract
The correlation between endothelial function and reactive oxygen species detecting from diabetic microvascular wall and the antioxidant effect of ascorbic acid (AA) during early and late phases of diabetic induction were determined. Male Spraque-Dawley rats were divided into four groups: control, diabetes rats (DM, using iv.injection of 55 mg/kg BW streptozotocin, (STZ)), and two groups of DM rats treated with AA (1 g/L, (STZ)) starting on day 2 (DM + AAday2) and week 6th (DM + AA6wk). On 12th week after STZ injection, the findings showed that in DM group, Ach (10(-5) M)-induced vasodilatation was decreased, while the number of leukocyte adhesion was increased significantly (P < 0.01). Interestingly, these abnormalities induced by DM could be protected or improved in both AA-treated groups, DM + AAday2 and DM + AA6wk. By using dihydrorhodamine 123, our findings also indicated that the existing of ROS productions on diabetic arteriolar and venular walls were different significantly (ROS(arteriole) = 165.89 ± 24.59 and ROS(venule) = 172.26 ± 34.70) (P < 0.05). Moreover by using BH4 inhibitor to induce increase in arteriolar ROS, the results also confirmed that AA could improve endothelial function with closed correlation to its potential to reduce vascular ROS content.
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Jenkins MJ, Edgley AJ, Sonobe T, Umetani K, Schwenke DO, Fujii Y, Brown RD, Kelly DJ, Shirai M, Pearson JT. Dynamic synchrotron imaging of diabetic rat coronary microcirculation in vivo. Arterioscler Thromb Vasc Biol 2011; 32:370-7. [PMID: 22075246 DOI: 10.1161/atvbaha.111.237172] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE In diabetes, long-term micro- and macrovascular damage often underlies the functional decline in the cardiovascular system. However, it remains unclear whether early-stage diabetes is associated with in vivo functional impairment in the coronary microvasculature. Synchrotron imaging allows us to detect and quantify regional differences in resistance microvessel caliber in vivo, even under conditions of high heart rate. METHODS AND RESULTS Synchrotron cine-angiograms of the coronary vasculature were recorded using anesthetized Sprague-Dawley rats 3 weeks after treatment with vehicle or streptozotocin (diabetic). In the early diabetic state, in the presence of nitric oxide and prostacyclin, vessel diameters were smaller (P<0.01) and endothelium-dependent vessel recruitment was already depressed (P<0.05). Endothelium-dependent and -independent vasodilatory responses in individual coronary vessels were not different in vivo. Inhibition of NO and PGI(2) production in diabetes uncovered early localized impairment in dilation. Diabetic animals displayed focal stenoses and segmental constrictions during nitric oxide synthase/cyclooxygenase blockade, which persisted during acetylcholine infusion (P<0.05), and a strong trend toward loss of visible microvessels. CONCLUSIONS Synchrotron imaging provides a novel method to investigate coronary microvascular function in vivo at all levels of the arterial tree. Furthermore, we have shown that early-stage diabetes is associated with localized coronary microvascular endothelial dysfunction.
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Affiliation(s)
- Mathew J Jenkins
- Department of Cardiac Physiology, National Cerebral & Cardiovascular Research Center Research Institute, 5-7-1 Fujishirodai, Suita-shi, Osaka 565-8565, Japan.
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Badavi M, Abedi H, Dianat M, Sarkaki A. Exercise Training and Grape Seed Extract Co-administration Improve Endothelial Dysfunction of Mesenteric Vascular Bed in STZ-induced Diabetic Rats. INT J PHARMACOL 2011. [DOI: 10.3923/ijp.2011.813.820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Félétou M. The Endothelium, Part I: Multiple Functions of the Endothelial Cells -- Focus on Endothelium-Derived Vasoactive Mediators. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00031ed1v01y201105isp019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Leo CH, Hart JL, Woodman OL. Impairment of both nitric oxide-mediated and EDHF-type relaxation in small mesenteric arteries from rats with streptozotocin-induced diabetes. Br J Pharmacol 2011; 162:365-77. [PMID: 20840539 DOI: 10.1111/j.1476-5381.2010.01023.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE To investigate whether diabetes affects either or both nitric oxide (NO)-mediated and endothelium-derived hyperpolarizing factor (EDHF)-type relaxation in endothelium-dependent relaxation of mesenteric arteries from streptozotocin-induced diabetic rats. EXPERIMENTAL APPROACH Wire myography was employed to examine endothelial function of mesenteric arteries. Superoxide levels were measured by L-012 and lucigenin-enhanced chemiluminescence. Western blotting was used to quantify protein expression levels. KEY RESULTS Superoxide levels were significantly increased in diabetic mesenteric arteries compared with normal arteries. Diabetes significantly reduced the sensitivity to the endothelium-dependent relaxant, acetylcholine (ACh) in mesenteric arteries. When the contribution of NO to relaxation was abolished by N-nitro-L-arginine (L-NNA) + a soluble guanylate cyclase inhibitor (ODQ), the sensitivity to ACh was significantly decreased in the diabetic arteries compared with normal arteries, indicating an impaired EDHF-type relaxation despite increased expression of intermediate- and small-conductance calcium-activated potassium channels. Conversely, when the contribution of EDHF was inhibited with TRAM-34 + apamin + iberiotoxin, maximum relaxations to ACh were significantly decreased in diabetic compared with normal arteries, suggesting that the contribution of NO was also impaired by diabetes. Basal levels of NO release, indicated by contraction to L-NNA, were also significantly decreased in diabetic arteries. Western blot analysis demonstrated that diabetic arteries had an increased expression of Nox2, decreased pSer⁴⁷³ Akt and a reduced proportion of endothelial NO synthase (eNOS) expressed as a dimer, indicating uncoupling. CONCLUSION AND IMPLICATIONS The contribution of both NO and EDHF-type relaxations was impaired in diabetes and was caused by increased oxidative stress, decreased pSer⁴⁷³ Akt and/or eNOS uncoupling.
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Affiliation(s)
- C H Leo
- Health Innovation Research Institute, RMIT University, Bundoora, Victoria, Australia
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3',4'-Dihydroxyflavonol reduces superoxide and improves nitric oxide function in diabetic rat mesenteric arteries. PLoS One 2011; 6:e20813. [PMID: 21673968 PMCID: PMC3108977 DOI: 10.1371/journal.pone.0020813] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 05/10/2011] [Indexed: 12/20/2022] Open
Abstract
Background 3',4'-Dihydroxyflavonol (DiOHF) is an effective antioxidant that acutely preserves nitric oxide (NO) activity in the presence of elevated reactive oxygen species (ROS). We hypothesized that DiOHF treatment (7 days, 1 mg/kg per day s.c.) would improve relaxation in mesenteric arteries from diabetic rats where endothelial dysfunction is associated with elevated oxidant stress. Methodology/Principal Findings In mesenteric arteries from diabetic rats there was an increase in ROS, measured by L-012 and 2',7'-dichlorodihydrofluorescein diacetate fluorescence. NADPH oxidase-derived superoxide levels, assayed by lucigenin chemiluminescence, were also significantly increased in diabetic mesenteric arteries (diabetes, 4892±946 counts/mg versus normal 2486±344 counts/mg, n = 7–10, p<0.01) associated with an increase in Nox2 expression but DiOHF (2094±300 counts/mg, n = 10, p<0.001) reversed that effect. Acetylcholine (ACh)-induced relaxation of mesenteric arteries was assessed using wire myography (pEC50 = 7.94±0.13 n = 12). Diabetes significantly reduced the sensitivity to ACh and treatment with DiOHF prevented endothelial dysfunction (pEC50, diabetic 6.86±0.12 versus diabetic+DiOHF, 7.49±0.13, n = 11, p<0.01). The contribution of NO versus endothelium-derived hyperpolarizing factor (EDHF) to ACh-induced relaxation was assessed by evaluating responses in the presence of TRAM-34+apamin+iberiotoxin or N-nitro-L-arginine+ODQ respectively. Diabetes impaired the contribution of both NO (maximum relaxation, Rmax diabetic 24±7 versus normal, 68±10, n = 9–10, p<0.01) and EDHF (pEC50, diabetic 6.63±0.15 versus normal, 7.14±0.12, n = 10–11, p<0.01) to endothelium-dependent relaxation. DiOHF treatment did not significantly affect the EDHF contribution but enhanced NO-mediated relaxation (Rmax 69±6, n = 11, p<0.01). Western blotting demonstrated that diabetes also decreased expression and increased uncoupling of endothelial NO synthase (eNOS). Treatment of the diabetic rats with DiOHF significantly reduced vascular ROS and restored NO-mediated endothelium-dependent relaxation. Treatment of the diabetic rats with DiOHF also increased eNOS expression, both in total and as a dimer. Conclusions/Significance DiOHF improves NO activity in diabetes by reducing Nox2-dependent superoxide production and preventing eNOS uncoupling to improve endothelial function.
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Gao X, Martinez-Lemus LA, Zhang C. Endothelium-derived hyperpolarizing factor and diabetes. World J Cardiol 2011; 3:25-31. [PMID: 21286215 PMCID: PMC3030734 DOI: 10.4330/wjc.v3.i1.25] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 11/30/2010] [Accepted: 12/07/2010] [Indexed: 02/06/2023] Open
Abstract
In addition to its role as a barrier between blood and tissues, the vascular endothelium is responsible for the synthesis and released of a number of vasodilators including prostaglandins, nitric oxide and endothelium-derived hyperpolarizing factor (EDHF). As one of these vasodilators, the specific nature of EDHF has not been fully elucidated, although a number of roles have been proposed. Importantly, many conditions, such as hypertension, hyperlipidemia, heart failure, ischemia-reperfusion and diabetes mellitus comprise vascular endothelial dysfunction with EDHF dysregulation. This article reviews reports on the role of EDHF in diabetes-related endothelial dysfunction.
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Affiliation(s)
- Xue Gao
- Xue Gao, Department of Physiology, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100005, China
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33
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Fatehi-Hassanabad Z, Chan CB, Furman BL. Reactive oxygen species and endothelial function in diabetes. Eur J Pharmacol 2010; 636:8-17. [DOI: 10.1016/j.ejphar.2010.03.048] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 02/27/2010] [Accepted: 03/22/2010] [Indexed: 02/07/2023]
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Ding H, Triggle CR. Endothelial dysfunction in diabetes: multiple targets for treatment. Pflugers Arch 2010; 459:977-94. [PMID: 20238124 DOI: 10.1007/s00424-010-0807-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 02/13/2010] [Accepted: 02/16/2010] [Indexed: 12/20/2022]
Abstract
Robert Furchgott's discovery of the obligatory role that the endothelium plays in the regulation of vascular tone has proved to be a major advance in terms of our understanding of the cellular basis of diabetic vascular disease. Endothelial dysfunction, as defined by a reduction in the vasodilatation response to an endothelium-dependent vasodilator (such as acetylcholine) or to flow-mediated vasodilatation, is an early indicator for the development of the micro- and macroangipathy that is associated with diabetes. In diabetes, hyperglycaemia plays a key role in the initiation and development of endothelial dysfunction; however, the cellular mechanisms involved as well as the importance of dyslipidaemia and co-morbidities such as hypertension and obesity remain incompletely understood. In this review, we discuss the mechanisms whereby hyperglycaemia, oxidative stress and dyslipidaemia can alter endothelial function and highlight their effects on endothelial nitric oxide synthase (eNOS), the endothelium-dependent hyperpolarising factor (EDHF) pathway(s), as well as on the role of endothelium-derived contracting factors (EDCFs) and adipocyte-derived vasoactive factors such as adipose-derived relaxing factor (ADRF).
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Affiliation(s)
- Hong Ding
- Department of Pharmacology & Medical Education, Weill Cornell Medical College in Qatar, P.O. Box 24144, Education City, Doha, Qatar
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Matsumoto T, Ishida K, Taguchi K, Kobayashi T, Kamata K. Losartan normalizes endothelium-derived hyperpolarizing factor-mediated relaxation by activating Ca2+-activated K+ channels in mesenteric artery from type 2 diabetic GK rat. J Pharmacol Sci 2010; 112:299-309. [PMID: 20168046 DOI: 10.1254/jphs.09308fp] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Ca(2+)-activated K(+) (K(Ca)) channels are important for endothelium-derived hyperpolarizing factor (EDHF) signaling. Since treatment with angiotensin II receptor blockers (ARBs) improves vasculopathies in type 2 diabetic patients, we asked whether the EDHF-type relaxation and its associated K(Ca) channels [small (SK(Ca))-, intermediate (IK(Ca))-, and large (BK(Ca))-conductance channels] are abnormal in mesenteric arteries isolated from Goto-Kakizaki (GK) rats at the chronic stage of type 2 diabetes (34 - 38 weeks) and whether an ARBs (losartan, 25 mg . kg(-1) . day(-1) for 2 weeks) might correct these abnormalities. Although the acetylcholine chloride-induced EDHF-type relaxation in mesenteric arteries from GK rats was reduced versus the Wistar controls, it was significantly restored by losartan treatment. The SK(Ca)-blocker apamin or the IK(Ca)-blocker 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34) inhibited such relaxations in the losartan-treated or -untreated Wistar groups and in the losartan-treated GK group, but not in the losartan-untreated GK group. The BK(Ca)-blocker iberiotoxin had a significant inhibitory effect in only one of these groups, the losartan-treated GK. The relaxations induced by the SK(Ca)/IK(Ca) activator NS309 and the BK(Ca) activator NS1619, which were impaired in GK rats, were normalized by losartan treatment. We conclude that losartan improves EDHF-type relaxation in GK rats at least partly by normalizing SK(Ca)/IK(Ca) activities and increasing BK(Ca) activity.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
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36
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Heberlein KR, Straub AC, Best AK, Greyson MA, Looft-Wilson RC, Sharma PR, Meher A, Leitinger N, Isakson BE. Plasminogen activator inhibitor-1 regulates myoendothelial junction formation. Circ Res 2010; 106:1092-102. [PMID: 20133900 DOI: 10.1161/circresaha.109.215723] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Plasminogen activator inhibitor-1 (PAI-1) is a biomarker for several vascular disease states; however, its target of action within the vessel wall is undefined. OBJECTIVE Determine the ability of PAI-1 to regulate myoendothelial junction (MEJ) formation. METHODS AND RESULTS MEJs are found throughout the vasculature linking endothelial cells (ECs) and vascular smooth muscle cells. Using a vascular cell coculture we isolated MEJ fractions and performed two-dimensional differential gel electrophoresis. Mass spectrometry identified PAI-1 as being enriched within MEJ fractions, which we confirmed in vivo. In the vascular cell coculture, recombinant PAI-1 added to the EC monolayer significantly increased MEJs. Conversely, addition of a PAI-1 monoclonal antibody to the EC monolayer reduced the number of MEJs. This was also observed in vivo where mice fed a high fat diet had increased PAI-1 and MEJs and the number of MEJs in coronary arterioles of PAI-1(-/-) mice was significantly reduced when compared to C57Bl/6 mice. The presence of MEJs in PAI-1(-/-) coronary arterioles was restored when their hearts were transplanted into and exposed to the circulation of C57Bl/6 mice. Application of biotin-conjugated PAI-1 to the EC monolayer in vitro confirmed the ability of luminal PAI-1 to translocate to the MEJ. Functionally, phenylephrine-induced heterocellular calcium communication in the vascular cell coculture was temporally enhanced when recombinant PAI-1 was present, and prolonged when PAI-1 was absent. CONCLUSION Our data implicate circulating PAI-1 as a key regulator of MEJ formation and a potential target for pharmacological intervention in diseases with vascular abnormalities (eg, diabetes mellitus).
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Affiliation(s)
- Katherine R Heberlein
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
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ATP-sensitive potassium channels contribute to the time-dependent alteration in the pentylenetetrazole-induced seizure threshold in diabetic mice. Seizure 2010; 19:53-8. [DOI: 10.1016/j.seizure.2009.11.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 11/10/2009] [Accepted: 11/13/2009] [Indexed: 01/29/2023] Open
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Brøndum E, Kold-Petersen H, Simonsen U, Aalkjaer C. NS309 restores EDHF-type relaxation in mesenteric small arteries from type 2 diabetic ZDF rats. Br J Pharmacol 2010; 159:154-65. [PMID: 20015296 PMCID: PMC2823361 DOI: 10.1111/j.1476-5381.2009.00525.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 06/19/2009] [Accepted: 09/03/2009] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The endothelium-derived hyperpolarizing factor (EDHF)-type relaxation in mesenteric small arteries from 21 week old Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats was investigated using (6,7-dichloro-1H-indole-2,3-dione 3-oxime) (NS309), a potent activator of small-conductance, calcium-activated potassium channel (SK(Ca)) and intermediate-conductance, calcium-activated potassium channel (IK(Ca)). EXPERIMENTAL APPROACH In the presence of inhibitors of cyclooxygenase and nitric oxide synthase [indomethacin and N(omega)-nitro-L-arginine methyl ester (l-NAME), respectively], acetylcholine (ACh)-induced hyperpolarization and EDHF-type relaxation were investigated under isometric conditions in the wire myograph using 0.5 and 1 microM NS309 and/or selective blockers of SK(Ca) and IK(Ca) channels. Membrane potential was recorded with glass microelectrodes, and changes in the intracellular calcium concentration of endothelial cells were visualized by confocal microscopy. SK(Ca) expression was assessed by Western blotting. KEY RESULTS In arteries from ZDF rats, ACh-induced relaxation and membrane hyperpolarization were attenuated and, compared with arteries from ZL rats, NS309 was less potent at causing relaxation. Incubation with 0.5 microM NS309 did not increase ACh-induced relaxation in arteries from ZDF rats significantly. However, 1 microM NS309 restored it (both in the absence and in the presence of indomethacin and l-NAME) without changing endothelial intracellular calcium concentration. The restored EDHF-type relaxation was more sensitive to TRAM-34 (1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole) (1 microM) than to apamin. Expression of the SK(Ca) channel was unaltered. CONCLUSIONS AND IMPLICATIONS The attenuated EDHF-type relaxation in mesenteric small arteries from ZDF rats can be restored by NS309 without changes in the intracellular calcium concentration of endothelial cells. These results may have clinical implications for the treatment of endothelial dysfunction in overweight type 2 diabetic patients.
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Affiliation(s)
- E Brøndum
- The Water and Salt Research Center, Institute of Physiology and Biophysics, Aarhus University, DK-8000 Aarhus C, Denmark
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Abstract
Vascular complications are an important pathological issue in diabetes that lead to the further functional deterioration of several organs. The balance between endothelium-dependent relaxing factors and endothelium-dependent contracting factors (EDCFs) is crucial in controlling local vascular tone and function under normal conditions. Diabetic endothelial dysfunction is characterized by reduced endothelium-dependent relaxations and/or enhanced endothelium-dependent contractions. Elevated levels of oxygen-derived free radicals are the initial source of endothelial dysfunction in diabetes. Oxygen-derived free radicals not only reduce nitric oxide bioavailability, but also facilitate the production and/or action of EDCFs. Thus, the endothelial balance tips towards vasoconstrictor responses over the course of diabetes.
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Affiliation(s)
- Yi Shi
- Institute of Physiology, University of Zurich, Switzerland
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40
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Kavak S, Emre M, Meral I, Unlugenc H, Pelit A, Demirkazik A. Repetitive 50 Hz pulsed electromagnetic field ameliorates the diabetes-induced impairments in the relaxation response of rat thoracic aorta rings. Int J Radiat Biol 2009; 85:672-9. [PMID: 19579070 DOI: 10.1080/09553000903009522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To evaluate the characteristic features of mechanical responses and the membrane potential changes induced by repetitive pulsed electromagnetic field (PEMF, 50 Hz, 5 mT) in thoracic aorta rings obtained from streptozotocin-induced diabetic and healthy control rats to determine if PEMF could ameliorate problems associated with diabetes. METHODS Sixty male Wistar rats weighing 250-290 g were randomly divided into two experimental groups, each containing 30 animals. Streptozotocin was given via tail vein to produce diabetes mellitus (DM) in the first group rats. The second group rats were treated only with % 0.9 saline and considered as non-DM group. Both groups were also divided into two subgroups as DM + PEMF, DM + sham, PEMF and sham, each containing 15 animals. Although the DM + PEMF and PEMF groups were treated, the DM + sham and sham groups were not treated with PEMF. The PEMF treatment occurred four times daily for 30 min at 15-min intervals repeated daily for 30 days. Thoracic aorta rings from both DM and non-DM rats exposed to PEMF were evaluated for contraction and relaxation responses and membrane potential changes in the presence or absence of chemical agents that were selected to test various modes of action. RESULTS Relaxation response of thoracic aorta rings was significantly reduced in DM than non-DM group. PEMF treatment significantly increased the relaxation response of the diabetic rings to acetylcholine, and reduced the concentration response to phenylephrine. Resting membrane potential was significantly higher in DM than in non-DM group. Inhibitors of nitric oxide (NO), both nitro-L-arginine (L-NO-ARG) and L-NO-ARG + indometacin combination, produced a significant transient hyperpolarisation in all groups. Inhibitors of potassium channel activity, charybdotoxin or apamine, produced a membrane depolarisation. However, PEMF did not induce any significant effect on the membrane potential in DM group. CONCLUSIONS Diabetes reduced the relaxation response of thoracic aorta rings. It also affected the membrane potentials of the rings. Treatment with PEMF ameliorated the diabetes-induced impairments in the relaxation response of these rings.
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Affiliation(s)
- Servet Kavak
- Department of Biophysics, Yuzuncu Yil University, Van, Turkey.
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Kansui Y, Goto K, Fujii K, Oniki H, Matsumura K, Iida M. CILOSTAMIDE PRODUCES HYPERPOLARIZATION ASSOCIATED WITH KATPCHANNEL ACTIVATION, BUT DOES NOT AUGMENT ENDOTHELIUM-DERIVED HYPERPOLARIZATION IN RAT MESENTERIC ARTERIES. Clin Exp Pharmacol Physiol 2009; 36:729-33. [DOI: 10.1111/j.1440-1681.2009.05142.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Subramaniam G, Achike FI, Mustafa MR. Characterizing the Mechanisms of Insulin Vasodilatation of Normal and Streptozotocin-induced Diabetic Rat Aorta. J Cardiovasc Pharmacol 2009; 53:333-40. [DOI: 10.1097/fjc.0b013e31819fd4a7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Heberlein KR, Straub AC, Isakson BE. The myoendothelial junction: breaking through the matrix? Microcirculation 2009; 16:307-22. [PMID: 19330678 DOI: 10.1080/10739680902744404] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Within the vasculature, specialized cellular extensions from endothelium (and sometimes smooth muscle) protrude through the extracellular matrix where they interact with the opposing cell type. These structures, termed myoendothelial junctions, have been cited as a possible key element in the control of several vascular physiologies and pathologies. This review will discuss observations that have led to a focus on the myoendothelial junction as a cellular integration point in the vasculature for both homeostatic and pathological conditions and as a possible independent signaling entity. We will also highlight the need for novel approaches to studying the myoendothelial junction in order to comprehend the cellular biology associated with this structure.
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Affiliation(s)
- Katherine R Heberlein
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottsville, Virginia 22908, USA
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44
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Endothelium-derived hyperpolarizing factor in vascular physiology and cardiovascular disease. Atherosclerosis 2009; 202:330-44. [DOI: 10.1016/j.atherosclerosis.2008.06.008] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 05/16/2008] [Accepted: 06/11/2008] [Indexed: 12/20/2022]
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Nacci C, Tarquinio M, De Benedictis L, Mauro A, Zigrino A, Carratù MR, Quon MJ, Montagnani M. Endothelial dysfunction in mice with streptozotocin-induced type 1 diabetes is opposed by compensatory overexpression of cyclooxygenase-2 in the vasculature. Endocrinology 2009; 150:849-61. [PMID: 18845644 PMCID: PMC2646543 DOI: 10.1210/en.2008-1069] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cardiovascular complications of diabetes result from endothelial dysfunction secondary to persistent hyperglycemia. We investigated potential compensatory mechanisms in the vasculature that oppose endothelial dysfunction in diabetes. BALB/c mice were treated with streptozotocin (STZ) to induce type 1 diabetes (T1D). In mesenteric vascular beds (MVBs), isolated ex vivo from mice treated with STZ for 1 wk, dose-dependent vasorelaxation to acetylcholine (ACh) or sodium nitroprusside was comparable with that in age-matched control mice (CTRL). By contrast, MVBs from mice treated with STZ for 8 wk had severely impaired vasodilator responses to ACh consistent with endothelial dysfunction. Pretreatment of MVBs from CTRL mice with nitric oxide synthase inhibitor nearly abolished vasodilation to ACh. In MVB from 1-wk STZ-treated mice, vasodilation to ACh was only partially impaired by L-N(omega)-arginine methyl ester. Thus, vasculature of mice with T1D may have compensatory nitric oxide-independent mechanisms to augment vasodilation to ACh and oppose endothelial dysfunction. Indeed, pretreatment of MVBs isolated from 1-wk STZ-treated mice with NS-398 [selective cyclooxygenase (COX)-2 inhibitor] unmasked endothelial dysfunction not evident in CTRL mice pretreated without or with NS-398. Expression of COX-2 in MVBs, aortic endothelial cells, and aortic vascular smooth muscle cells from STZ-treated mice was significantly increased (vs. CTRL). Moreover, concentrations of the COX-2-dependent vasodilator 6-keto-prostaglandin F-1alpha was elevated in conditioned media from aorta of STZ-treated mice. We conclude that endothelial dysfunction in a mouse model of T1D is opposed by compensatory up-regulation of COX-2 expression and activity in the vasculature that may be relevant to developing novel therapeutic strategies for diabetes and its cardiovascular complications.
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MESH Headings
- Animals
- Cells, Cultured
- Cyclooxygenase 2/metabolism
- Cyclooxygenase 2/physiology
- Cyclooxygenase 2 Inhibitors/pharmacology
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/physiopathology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/physiopathology
- Male
- Mice
- Mice, Inbred BALB C
- NG-Nitroarginine Methyl Ester/pharmacology
- Nitric Oxide Synthase Type III/metabolism
- Nitrobenzenes/pharmacology
- Oncogene Protein v-akt/metabolism
- Streptozocin
- Sulfonamides/pharmacology
- Up-Regulation/drug effects
- Up-Regulation/physiology
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Affiliation(s)
- Carmela Nacci
- Department of Pharmacology and Human Physiology, University of Bari Medical School, Bari, Italy
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Park Y, Capobianco S, Gao X, Falck JR, Dellsperger KC, Zhang C. Role of EDHF in type 2 diabetes-induced endothelial dysfunction. Am J Physiol Heart Circ Physiol 2008; 295:H1982-8. [PMID: 18790831 DOI: 10.1152/ajpheart.01261.2007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Endothelium-derived hyperpolarizing factor (EDHF) plays a crucial role in modulating vasomotor tone, especially in microvessels when nitric oxide-dependent control is compromised such as in diabetes. Epoxyeicosatrienoic acids (EETs), potassium ions (K+), and hydrogen peroxide (H2O2) are proposed as EDHFs. However, the identity (or identities) of EDHF-dependent endothelial dilators has not been clearly elucidated in diabetes. We assessed the mechanisms of EDHF-induced vasodilation in wild-type (WT, normal), db/db (advanced type 2 diabetic) mice, and db/db mice null for TNF (dbTNF-/dbTNF-). In db/db mice, EDHF-induced vasodilation [ACh-induced vasodilation in the presence of N(G)-nitro-L-arginine methyl ester (L-NAME, 10 micromol/l) and prostaglandin synthase inhibitor indomethacin (Indo, 10 mumol/l)] was diminished after the administration of catalase (an enzyme that selectively dismutates H2O2 to water and oxygen, 1,000 U/ml); administration of the combination of charybdotoxin (a nonselective blocker of intermediate-conductance Ca2+-activated K+ channels, 10 micromol/l) and apamin (a selective blocker of small-conductance Ca2+-activated K+ channels, 50 micromol/l) also attenuated EDHF-induced vasodilation, but the inhibition of EETs synthesis [14,15-epoxyeicosa-5(Z)-enoic acid; 10 mumol/l] did not alter EDHF-induced vasodilation. In WT controls, EDHF-dependent vasodilation was significantly diminished after an inhibition of K+ channel, EETs synthesis, or H2O2 production. Our molecular results indicate that mRNA and protein expression of interleukin-6 (IL-6) were greater in db/db versus WT and dbTNF-/dbTNF- mice, but neutralizing antibody to IL-6 (anti-IL-6; 0.28 mg.ml(-1).kg(-1) ip for 3 days) attenuated IL-6 expression in db/db mice. The incubation of the microvessels with IL-6 (5 ng/ml) induced endothelial dysfunction in the presence of l-NAME and Indo in WT mice, but anti-IL-6 restored ACh-induced vasodilation in the presence of L-NAME and Indo in db/db mice. In db(TNF-)/db(TNF-) mice, EDHF-induced vasodilation was greater and comparable with controls, but IL-6 decreased EDHF-mediated vasodilation. Our results indicate that EDHF compensates for diminished NO-dependent dilation in IL-6-induced endothelial dysfunction by the activation of H2O2 or a K+ channel in type 2 diabetes.
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Affiliation(s)
- Yoonjung Park
- Department of Internal Medicine, Medical Pharmacology and Physiology and Nutritional Science, Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO 65211, USA
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Hinds MT, Ma M, Tran N, Ensley AE, Kladakis SM, Vartanian KB, Markway BD, Nerem RM, Hanson SR. Potential of baboon endothelial progenitor cells for tissue engineered vascular grafts. J Biomed Mater Res A 2008; 86:804-12. [DOI: 10.1002/jbm.a.31672] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Edgley AJ, Tare M, Evans RG, Skordilis C, Parkington HC. In vivo regulation of endothelium-dependent vasodilation in the rat renal circulation and the effect of streptozotocin-induced diabetes. Am J Physiol Regul Integr Comp Physiol 2008; 295:R829-39. [DOI: 10.1152/ajpregu.00861.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We assessed the relative contributions of endothelium-derived relaxing factors to renal vasodilation in vivo and determined whether these are altered in established streptozotocin-induced diabetes. In nondiabetic rats, stimulation of the endothelium by locally administered ACh or bradykinin-induced transient renal hyperemia. Neither basal renal blood flow (RBF) nor renal hyperemic responses to ACh or bradykinin were altered by blockade of prostanoid production (indomethacin) or by administration of charybdotoxin (ChTx) plus apamin to block endothelium-derived hyperpolarizing factor (EDHF). In contrast, combined blockade of nitric oxide (NO) synthase, Nω-nitro-l-arginine methyl ester (l-NAME), and prostanoid production reduced basal RBF and the duration of the hyperemic responses to ACh and bradykinin and revealed a delayed ischemic response to ACh. Accordingly, l-NAME and indomethacin markedly reduced integrated (area under the curve) hyperemic responses to ACh and bradykinin. Peak increases in RBF in response to ACh and bradykinin were not reduced by l-NAME and indomethacin but were reduced by subsequent blockade of EDHF. l-NAME plus indomethacin and ChTx plus apamin altered RBF responses to endothelium stimulation in a qualitatively similar fashion in diabetic and nondiabetic rats. The integrated renal hyperemic responses to ACh and bradykinin were blunted in diabetes, due to a diminished contribution of the component abolished by l-NAME plus indomethacin. We conclude that NO dominates integrated hyperemic responses to ACh and bradykinin in the rat kidney in vivo. After prior inhibition of NO synthase, EDHF mediates transient renal vasodilation in vivo. Renal endothelium-dependent vasodilation is diminished in diabetes due to impaired NO function.
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The expression and function of Ca(2+)-sensing receptors in rat mesenteric artery; comparative studies using a model of type II diabetes. Br J Pharmacol 2008; 154:652-62. [PMID: 18414396 DOI: 10.1038/bjp.2008.108] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND AND PURPOSE The extracellular calcium-sensing receptor (CaR) in vascular endothelial cells activates endothelial intermediate-conductance, calcium-sensitive K(+) channels (IK(Ca)) indirectly leading to myocyte hyperpolarization. We determined whether CaR expression and function was modified in a rat model of type II diabetes. EXPERIMENTAL APPROACH Pressure myography, western blotting, sharp microelectrode and K(+)-selective electrode recordings were used to investigate the functional expression of the CaR and IK(Ca) in rat mesenteric arteries. KEY RESULTS Myocyte hyperpolarization to the CaR activator calindol was inhibited by Calhex 231. U46619-induced vessel contraction elevated the extracellular [K(+)] around the myocytes, and inhibition of this 'K(+) cloud' by iberiotoxin was needed to reveal calindol-induced vasodilatations. These were antagonized by Calhex 231 and significantly smaller in Zucker diabetic fatty rat (ZDF) vessels than in Zucker lean (ZL) controls. Myocyte hyperpolarizations to calindol were also smaller in ZDF than in ZL arteries. In ZDF vessels, endothelial cell CaR protein expression was reduced; IK(Ca) expression was also diminished, but IK(Ca)-generated hyperpolarizations mediated by 1-EBIO were unaffected. CONCLUSIONS AND IMPLICATIONS The reduced CaR-mediated hyperpolarizing and vasodilator responses in ZDF arteries result from a decrease in CaR expression, rather than from a modification of IK(Ca) channels. Detection of CaR-mediated vasodilatation required the presence of iberiotoxin, suggesting a CaR contribution to vascular diameter, that is, inversely related to the degree of vasoconstriction. Compromise of the CaR pathway would favour the long-term development of a higher basal vascular tone and could contribute to the vascular complications associated with type II diabetes.
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