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Sorop O, van den Heuvel M, van Ditzhuijzen NS, de Beer VJ, Heinonen I, van Duin RWB, Zhou Z, Koopmans SJ, Merkus D, van der Giessen WJ, Danser AHJ, Duncker DJ. Coronary microvascular dysfunction after long-term diabetes and hypercholesterolemia. Am J Physiol Heart Circ Physiol 2016; 311:H1339-H1351. [PMID: 27591223 DOI: 10.1152/ajpheart.00458.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/01/2016] [Indexed: 02/07/2023]
Abstract
Coronary microvascular dysfunction (CMD) has been proposed as an important component of diabetes mellitus (DM)- and hypercholesterolemia-associated coronary artery disease (CAD). Previously we observed that 2.5 mo of DM and high-fat diet (HFD) in swine blunted bradykinin (BK)-induced vasodilation and attenuated endothelin (ET)-1-mediated vasoconstriction. Here we studied the progression of CMD after 15 mo in the same animal model of CAD. Ten male swine were fed a HFD in the absence (HFD, n = 5) or presence of streptozotocin-induced DM (DM + HFD, n = 5). Responses of small (∼300-μm-diameter) coronary arteries to BK, ET-1, and the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine were examined in vitro and compared with those of healthy (Normal) swine (n = 12). Blood glucose was elevated in DM + HFD (17.6 ± 4.5 mmol/l) compared with HFD (5.1 ± 0.4 mmol/l) and Normal (5.8 ± 0.6 mmol/l) swine, while cholesterol was markedly elevated in DM + HFD (16.8 ± 1.7 mmol/l) and HFD (18.1 ± 2.6 mmol/l) compared with Normal (2.1 ± 0.2 mmol/l) swine (all P < 0.05). Small coronary arteries showed early atherosclerotic plaques in HFD and DM + HFD swine. Surprisingly, DM + HFD and HFD swine maintained BK responsiveness compared with Normal swine due to an increase in NO availability relative to endothelium-derived hyperpolarizing factors. However, ET-1 responsiveness was greater in HFD and DM + HFD than Normal swine (both P < 0.05), resulting mainly from ETB receptor-mediated vasoconstriction. Moreover, the calculated vascular stiffness coefficient was higher in DM + HFD and HFD than Normal swine (both P < 0.05). In conclusion, 15 mo of DM + HFD, as well as HFD alone, resulted in CMD. Although the overall vasodilation to BK was unperturbed, the relative contributions of NO and endothelium-derived hyperpolarizing factor pathways were altered. Moreover, the vasoconstrictor response to ET-1 was enhanced, involving the ETB receptors. In conjunction with our previous study, these findings highlight the time dependence of the phenotype of CMD.
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Affiliation(s)
- Oana Sorop
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands.,Netherlands Heart Institute, Utrecht, The Netherlands; and
| | - Mieke van den Heuvel
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands.,Department of Internal Medicine, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Nienke S van Ditzhuijzen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Vincent J de Beer
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ilkka Heinonen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Richard W B van Duin
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Zhichao Zhou
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Sietse J Koopmans
- Livestock Research, Wageningen University and Research Center, Wageningen, The Netherlands
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Wim J van der Giessen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands.,Netherlands Heart Institute, Utrecht, The Netherlands; and
| | - A H Jan Danser
- Department of Internal Medicine, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Dirk Jan Duncker
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands;
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Abstract
Dysfunction of the endothelial cell monolayer leads to increased vascular tone and permeability and a prothrombotic environment. Type 2 diabetes is a state of insulin resistance, hyperglycaemia and dyslipidaemia characterised by high cardiovascular risk and accelerated atherosclerosis. Many mechanisms by which hyperglycaemia can result in endothelial dysfunction have now been identified. However, the presence of endothelial dysfunction in normoglycaemic first-degree relatives and insulin resistant subjects is less well understood and less readily explained by `confounding' variables. We suggest that insulin's effects on glucose transport in classical target tissues and nitric oxide production in the endothelium are fundamentally linked at a molecular level. It is expected that greater understanding of these underlying mechanisms will lead to novel approaches to prevention of cardiovascular disease in both diabetic and non-diabetic subjects.
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Affiliation(s)
- Andrew M Storey
- University Department of Medicine, Glasgow Royal Infirmary, Human Nutrition, Glasgow Royal Infirmary, Glasgow, UK
| | - Colin J Perry
- University Department of Medicine, Glasgow Royal Infirmary
| | - John R Petrie
- University Department of Medicine, Glasgow Royal Infirmary,
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van den Heuvel M, Sorop O, Koopmans SJ, Dekker R, de Vries R, van Beusekom HMM, Eringa EC, Duncker DJ, Danser AHJ, van der Giessen WJ. Coronary microvascular dysfunction in a porcine model of early atherosclerosis and diabetes. Am J Physiol Heart Circ Physiol 2011; 302:H85-94. [PMID: 21984550 DOI: 10.1152/ajpheart.00311.2011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Detailed evaluation of coronary function early in diabetes mellitus (DM)-associated coronary artery disease (CAD) development is difficult in patients. Therefore, we investigated coronary conduit and small artery function in a preatherosclerotic DM porcine model with type 2 characteristics. Streptozotocin-induced DM pigs on a saturated fat/cholesterol (SFC) diet (SFC + DM) were compared with control pigs on SFC and standard (control) diets. SFC + DM pigs showed DM-associated metabolic alterations and early atherosclerosis development in the aorta. Endothelium-dependent vasodilation to bradykinin (BK), with or without blockade of nitric oxide (NO) synthase, endothelium-independent vasodilation to an exogenous NO-donor (S-nitroso-N-acetylpenicillamine), and vasoconstriction to endothelin (ET)-1 with blockade of receptor subtypes, were assessed in vitro. Small coronary arteries, but not conduit vessels, showed functional alterations including impaired BK-induced vasodilatation due to loss of NO (P < 0.01 vs. SFC and control) and reduced vasoconstriction to ET-1 (P < 0.01 vs. SFC and control), due to a decreased ET(A) receptor dominance. Other vasomotor responses were unaltered. In conclusion, this model demonstrates specific coronary microvascular alterations with regard to NO and ET-1 systems in the process of early atherosclerosis in DM. In particular, the altered ET-1 system correlated with hyperglycemia in atherogenic conditions, emphasizing the importance of this system in DM-associated CAD development.
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Affiliation(s)
- Mieke van den Heuvel
- Department of Cardiology, Division of Pharmacology, Vascular and Metabolic Diseases, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
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Kyriakides ZS, Kremastinos DT, Raptis AE, Johnston N, Raptis SA, Webb DJ, Kyrzopoulos S, Sbarouni E. Impaired effect of endothelin-1 on coronary artery stiffness in type 2 diabetes. Int J Cardiol 2006; 112:207-12. [PMID: 16325943 DOI: 10.1016/j.ijcard.2005.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 08/04/2005] [Accepted: 09/18/2005] [Indexed: 11/29/2022]
Abstract
AIM We examined whether there is a differential effect of endothelin-A antagonism on coronary artery compliance in type 2 diabetes mellitus compared to non-diabetic patients. PATIENT AND METHODS We examined 32 patients, 11 type 2 diabetes mellitus and 21 non-diabetic patients, with atherosclerotic epicardial arteries free of significant luminal stenoses. Intracoronary BQ-123 (6 micromol), an endothelin-A receptor antagonist, was infused over 20 min. The artery lumen area in the proximal arterial segment was measured at end diastole and end systole before and after BQ-123 administration using an intravascular ultrasound catheter. Calculations were made of normalized arterial compliance index, in mm Hg(-1) x 10(3) and of arterial stiffness index beta. RESULTS Pulse pressure and heart rate did not change after BQ-123. In type 2 diabetes mellitus, normalized compliance index decreased from 1.79+/-1.36 at baseline to 1.29+/-0.82 after BQ-123 administration, whereas in non-diabetic patients it increased from 2.10+/-1.36 to 3.00+/-2.07 (p<0.05 versus baseline) (F=6.39, p=0.02). In type 2 diabetes mellitus, beta index increased from 1.97+/-0.53 to 2.46+/-0.95, whereas in non-diabetic patients it decreased from 1.83+/-0.95 to 1.63+/-0.84 (F=7.80, p=0.009). Big endothelin-1 at baseline was correlated with the baseline beta index (p<0.0001, r=0.68). CONCLUSIONS Big endothelin-1 is correlated with the coronary artery stiffness. The effect of endogenous endothelin-1 on coronary artery stiffness is impaired in type 2 diabetes mellitus. This may have important therapeutic implications with respect to the introduction of endothelin receptor antagonists as cardiovascular therapeutic agents.
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Lott MEJ, Hogeman C, Herr M, Gabbay R, Sinoway LI. Effects of an oral glucose tolerance test on the myogenic response in healthy individuals. Am J Physiol Heart Circ Physiol 2006; 292:H304-10. [PMID: 16935998 DOI: 10.1152/ajpheart.00940.2005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The myogenic response, the inherent ability of blood vessels to rapidly respond to changes in transmural pressure, is involved in local blood flow autoregulation. Animal studies suggest that both acute hyperglycemia and hyperinsulinemia may impair myogenic vasoconstriction. The purpose of this study was to examine the effects of an oral glucose load on brachial mean blood velocity (MBV) during increases in forearm transmural pressure in humans. Eight healthy men and women (38 +/- 5 yr) underwent an oral glucose tolerance test (OGTT). MBV (in cm/s; Doppler ultrasound) responses to a rise in forearm transmural pressure (arm tank suction, -50 mmHg) were studied before and every 30 min for 120 min during the OGTT. Before the start of the OGTT, MBV was lower than baseline values 30 and 60 s after the application of negative pressure. This suggests that myogenic constriction was present. During the OGTT, blood glucose rose from 88 +/- 2 to 120 +/- 6 mg/dl (P < 0.05) and insulin rose from 14 +/- 1 to 101 +/- 32 microU/ml (P < 0.05). Glucose loading attenuated the reduction in MBV with arm suction (Delta-0.73 +/- 0.14 vs. Delta-1.67 +/- 0.43 cm/s and Delta-1.07 +/- 0.14 vs. Delta-2.38 +/- 0.54 cm/s, respectively, during 30 and 60 s of suction postglucose compared with preglucose values; all P < 0.05). We observed no such time effect for myogenic responses during a sham OGTT. In an additional 5 subjects, glucose loading had no effect on brachial diameters with the application of negative pressure. Oral glucose loading leads to attenuated myogenic vasoconstriction in healthy individuals. The role that this diminished postglucose reactivity plays in mediating postprandial hypotension and/or orthostasis needs to be further explored.
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Affiliation(s)
- Mary E J Lott
- Cardiology, H047, Penn State College of Medicine, 500 University Dr., Hershey, PA 17033, USA
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Ajayi AA, Ogungbade GO, Okorodudu AO. Sex hormone regulation of systemic endothelial and renal microvascular reactivity in type-2 diabetes: studies in gonadectomized and sham-operated Zucker diabetic rats. Eur J Clin Invest 2004; 34:349-57. [PMID: 15147332 DOI: 10.1111/j.1365-2362.2004.01339.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Male Zucker diabetic rats exhibit a more severe endotheliopathy in comparison with their female diabetic litter mates. The plasma concentrations of both thromboxanes and endothelins are elevated in diabetes, and the receptor cross-talk between TXA(2) and ET-1 receptors may be enhanced in type-2 diabetic Zucker rats. AIMS To determine the role of the endogenous sex steroid hormones, testosterone and estradiol on the systemic and renal microvascular reactivity to ET-1, thromboxane-mimetic U46619, ET-TXA(2) receptor interaction, and the nitric oxide vasodilator system in Zucker hypertensive-diabetic rats. METHODS Male and female Zucker rats aged 8-10 weeks were each divided into two groups. The male rats were castrated or underwent a sham operation. The female rats were spayed (bilateral ovariectomy and hysterectomy) or had a sham operation. All rats were studied 4-6 weeks after the gonadectomy or sham operations. Blood glucose and insulin as well as plasma concentrations of testosterone and estradiol were determined. Haemodynamic studies were undertaken with determination of the dose-response curve for mean arterial pressure (MAP), renal cortical flow (RCF) and renal medullary blood flow (MBF) in response to ET-1 and U46619, and the effect of interdiction of the ET-TXA(2) interaction with ET-antagonists BQ610 and BQ788. The role of endogenous NO was assessed by its response to graded acetylcholine doses and to a L-NG-nitro-arginine methyl ester (L-NAME) infusion. RESULTS Castrated male rats had a significantly lower blood glucose concentration (295 +/- 33 mg dL(-1)) compared with their sham-controls (481 +/- 40 mg dL(-1)), P = 0.008. Mean arterial pressure tended to be lower in the castrated rats. Gonadectomy reduced the plasma testosterone and estradiol concentrations. Castration abolished the hypotensive action of U46619 compared with sham-operated male rats (P < 0.0001, anova). Conversely, the pressor action of U46619 seen in the sham-operated female rats was reversed to a profound hypotensive action in the spayed rats (P < 0.001, anova). The change in MAP after U46619 was inversely correlated to the plasma testosterone concentration (r = -0.73, P = 0.027). The paradoxical hypotensive response elicited by ET-1 in the Zucker diabetic rats of both sexes was abolished by castration only (P < 0.005, anova). Castration caused a significant (P = 0.011) augmentation of the vasodilator response to acetylcholine, while spaying caused a slight attenuation. Castration, but not spaying, resulted in significant increases in MBF after U46619 (P = 0.003, anova), ET-1 (P = 0.005, anova) and acetylcholine (P = 0.053, anova). The ET-(B) antagonist BQ788 augmented the U46619-induced rise in MAP in castrated male rats, and also abolished the U46619-induced increase in MBF (P < 0.01 anova). L-NAME (25 mg kg(-1)) increased MAP and decreased MBF in the gonadectomized and sham-operated rats, except for the castrated male Zucker rats, where it significantly increased MBF (+90 +/- 31 PU) (P = 0.0004, anova) despite the increase in MAP. CONCLUSIONS Testosterone and estradiol regulate systemic and microvascular reactivity to TXA(2) receptor stimulation in type-2 diabetic Zucker rats. The impact of testosterone on blood glucose concentration, blood pressure, and the systemic and renal microcirculatory response to ET-1 and NO, as well as the endothelin-thromboxane receptor cross talk, is greater, and opposite to that of estradiol. The effects of testosterone withdrawal may at least in part be mediated by the ET-B receptor subtype and NO generation. Androgen blockade should be investigated further for the reversal or delay of hypertensive-diabetic endotheliopathy.
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Affiliation(s)
- A A Ajayi
- Center for Cardiovascular Diseases, Texas Southern University, Houston, Texas 77004, USA.
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7
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Ajayi AA, Ogungbade GO, Hercule HC, Oyekan AO, Mutembei L. Alteration in endothelin receptor sub-type responsiveness and in the endothelin-TXA(2) mimetic U46619 interaction, in type-2 hypertensive diabetic Zucker rats. Diabetes Res Clin Pract 2004; 63:155-69. [PMID: 14757287 DOI: 10.1016/j.diabres.2003.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Type-2 diabetes is characterized by endotheliopathy, which increases target organ damage and mortality. There is excessive endothelin-1 and TXA(2) production, and abnormal vascular reactivity to endothelin-1, manifested as a paradoxical hypotensive action in Zucker diabetic, but not lean rats. We examined the hypothesis that there is an alteration in the ET-A/ET-B receptor subtype sensitivity, and/or the interaction or cross-talk between ET-1 and TXA(2) in type-2 diabetes, using Zucker diabetic rats and their lean littermates. MATERIALS AND METHODS Hemodynamic studies were performed in lean and Zucker fatty diabetic rats of both sexes. Laser doppler flowmetry was used to measure renal cortical (RCF) and medullary blood flow (MBF) responses. Dose response curves for mean arterial blood pressure (MAP), MBF and RCF in response to ET-1, U46619, acetylcholine, and L-NAME (25mg/kg) were constructed after pre-treatment of the rats with either BQ610 1mg/kg i.v. or BQ788 0.5mg/kg i.v. The effects of BQ610 and BQ788 on whole blood impedance aggregation were also assessed. RESULTS BQ788, but not BQ610 abolished both the paradoxical hypotensive action of ET-1 in Zucker diabetic rats (n=7 each, P<0.001 ANOVA) as well as the dose-dependent rise in MBF (P<0.001 ANOVA). BQ788, but not BQ610 abolished the difference in response to ET-1 between lean and diabetic Zucker rats. U46619 caused a hypotensive action in male Zucker rats which was abolished by L-NAME 25mg/kg or indomethacin 10mg/kg i.v. The U46619 interaction with BQ788 on both MAP and MBF was significantly (P<0.03 ANOVA) different between lean and diabetic Zucker rats. BQ788, but not BQ610 attenuated both the MAP and MBF responses to acetylcholine or L-NAME P<0.02 ANOVA). However, BQ610 dose-dependently attenuated the slope of platelet aggregation in both lean and Zucker diabetic rats (P<0.02 ANOVA). CONCLUSION ET-B receptor antagonism abolished the abnormal vascular reactivity and MBF responses to ET-1, and also normalized the vasoactive responses to the level seen in healthy lean Zucker rats. ET-1 receptor blockade influences the responses to TXA(2) receptor activation. In the systemic and renal circulation, this interaction appears to be mostly ET-B receptor mediated, whilst in platelets, ET-A receptor role may be predominant. The interaction or cross-talk between ET-1 and TXA(2) is altered in the type-2 diabetic state. Collectively, these pathophysiological changes may contribute to the vicious circle of diabetic endotheliopathy.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Acetylcholine/pharmacology
- Animals
- Antihypertensive Agents/pharmacology
- Blood Flow Velocity/drug effects
- Blood Pressure/drug effects
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/physiopathology
- Drug Interactions
- Endothelin A Receptor Antagonists
- Endothelin B Receptor Antagonists
- Endothelin-1/pharmacology
- Enzyme Inhibitors/pharmacology
- Hypertension/complications
- Hypertension/physiopathology
- Kidney Cortex/blood supply
- Kidney Medulla/blood supply
- Male
- NG-Nitroarginine Methyl Ester/pharmacology
- Oligopeptides/pharmacology
- Piperidines/pharmacology
- Platelet Aggregation/drug effects
- Rats
- Rats, Sprague-Dawley
- Rats, Zucker
- Receptor Cross-Talk
- Receptor, Endothelin A/drug effects
- Receptor, Endothelin A/physiology
- Receptor, Endothelin B/drug effects
- Receptor, Endothelin B/physiology
- Receptors, Endothelin/drug effects
- Receptors, Endothelin/physiology
- Thromboxane A2/pharmacology
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Affiliation(s)
- A A Ajayi
- Center for Cardiovascular Diseases, Texas Southern University, 3100 Cleburne Avenue, Houston, TX 77004, USA.
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McEniery CM, Qasem A, Schmitt M, Avolio AP, Cockcroft JR, Wilkinson IB. Endothelin-1 regulates arterial pulse wave velocity in vivo. J Am Coll Cardiol 2004; 42:1975-81. [PMID: 14662262 DOI: 10.1016/j.jacc.2003.06.016] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVES The aim of this study was to investigate whether endothelin-1, acting locally, regulates arterial distensibility, assessed by measuring pulse-wave velocity in vivo. BACKGROUND Arterial stiffness is a key determinant of cardiovascular risk. Several lines of evidence support a role for the endothelium in regulating arterial stiffness by release of vasoactive mediators. However, the role of endothelin-1 (ET-1) in the regulation of arterial stiffness has not been investigated. METHODS All studies were conducted in anesthetized sheep. Pulse wave velocity (PWV) was calculated using the foot-to-foot methodology from two pressure waveforms simultaneously recorded with a high-fidelity, dual pressure-sensing catheter placed in the common iliac artery. RESULTS Intra-arterial infusion of ET-1 significantly increased iliac PWV by 12 +/- 5% (mean +/- STD; p < 0.001), whereas infusion of the endothelin-A (ET(A)) receptor antagonist BQ-123 significantly reduced PWV by 12 +/- 4% (p < 0.001). After BQ-123 infusion, exogenously infused ET-1 did not significantly change PWV compared with infusion of saline (change of -0.08 +/- 0.11% vs. -0.01 +/- 0.07%; p = 0.53). Importantly, infusion of BQ-123 or ET-1 distal to the common iliac artery did not affect PWV. CONCLUSIONS These results demonstrate, for the first time, that endogenous ET-1 production directly regulates large artery PWV in vivo. In addition, exogenous ET-1 increases PWV, and this can be blunted by ET(A) receptor blockade. These observations explain, in part, why conditions that exhibit up-regulation of ET-1 are also associated with arterial stiffening. Therefore, drugs that block ET(A) receptors may be effective in reducing large artery stiffness in humans, and thus cardiovascular risk.
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Affiliation(s)
- Carmel M McEniery
- Clinical Pharmacology Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom.
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9
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McGavock JM, Eves ND, Mandic S, Glenn NM, Quinney HA, Haykowsky MJ. The Role of Exercise in the Treatment of Cardiovascular Disease Associated with Type 2 Diabetes Mellitus. Sports Med 2004; 34:27-48. [PMID: 14715038 DOI: 10.2165/00007256-200434010-00004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The role of exercise training in the prevention and treatment of type 2 diabetes mellitus has been studied extensively over the past two decades. Although the primary treatment aim for patients with type 2 diabetes is metabolic control, the morbidity and mortality associated with the disease is more a function of cardiovascular disease. As exercise is associated with favourable reductions in the risk for cardiovascular disease in other high-risk populations, here we explore the role of exercise in the treatment of cardiovascular maladaptations associated with type 2 diabetes. The cardiovascular adaptation to type 2 diabetes is characterised by hypertrophy, stiffening and loss of functional reserve. Clinically, the cardiovascular adaptations to the diabetic state are associated with an increased risk for cardiovascular disease. Functionally, these adaptations have been shown to contribute to a reduced exercise capacity, which may explain the reduced cardiovascular fitness observed in this population. Exercise training is associated with improved exercise capacity in various populations, including type 2 diabetes. Several structural and functional adaptations within the cardiovascular system following exercise training could explain these findings, such as reductions in ventricular and vascular structural hypertrophy and compliance coupled with increased functional reserve. Although these cardiovascular adaptations to aerobic exercise training have been well documented in older populations with similar decrements in cardiovascular fitness and function, they have yet to be examined in patients with type 2 diabetes. For this reason, we contend that exercise training may be an excellent therapeutic adjunct in the treatment of diabetic cardiovascular disease.
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Affiliation(s)
- Jonathan M McGavock
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada.
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10
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Yokota T, Ma RC, Park JY, Isshiki K, Sotiropoulos KB, Rauniyar RK, Bornfeldt KE, King GL. Role of protein kinase C on the expression of platelet-derived growth factor and endothelin-1 in the retina of diabetic rats and cultured retinal capillary pericytes. Diabetes 2003; 52:838-45. [PMID: 12606528 DOI: 10.2337/diabetes.52.3.838] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Increased expression of endothelin-1 (ET-1) is associated with diabetic retinopathy and vasculopathy, although the molecular explanation has not been defined. The effects of high glucose and protein kinase C (PKC) activation on platelet-derived growth factor (PDGF)-BB and of ET-1 expression in the retina of streptozotocin (STZ)-induced diabetic rats and bovine retinal pericytes (BRPC) were examined. In 4-week diabetic rats, PDGF-B and prepro-ET-1 (ppET-1) mRNA levels increased significantly by 2.8- and 1.9-fold, respectively, as quantified by RT-PCR. Treatment with PKC-beta isoform-specific inhibitor (LY333531) or insulin normalized retinal ET-1 and PDGF-B expression. In BRPC, high glucose levels increased ppET-1 and PDGF-B mRNA expression by 1.7- and 1.9-fold, respectively. The addition of PDGF-BB but not PDGF-AA increased expression of ppET-1 and vascular endothelial growth factor mRNA by 1.6- and 2.1-fold, respectively, with both inhibited by AG1296, a selective PDGF receptor kinase inhibitor. A general PKC inhibitor, GF109203X, suppressed PDGF-BB's induction of ET-1 mRNA. Thus, increased ET-1 expression in diabetic retina could be due to increased expression of PDGF-BB, mediated via PDGF-beta receptors in part by PKC activation. The novel demonstration of elevated expression of PDGF-B and its induction by PKC activation identifies a potential new molecular step in the pathogenesis of diabetic retinopathy.
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Affiliation(s)
- Tamotsu Yokota
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
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11
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Romagni P, Rossi F, Guerrini L, Quirini C, Santiemma V. Aldosterone induces contraction of the resistance arteries in man. Atherosclerosis 2003; 166:345-9. [PMID: 12535748 DOI: 10.1016/s0021-9150(02)00363-5] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Very rapid nongenomic effects of aldosterone in vitro have been described in recent years and in vivo evidence has been reported as well. In the present study, we investigated the rapid effect of aldosterone on resistance arteries in vivo in man. We performed a randomized, placebo-controlled, double-blind crossover study on ten healthy male volunteers. Forearm blood flow (FBF) was measured using venous occlusion plethysmography in both forearms. FBF was reduced by administration of aldosterone 2.5 pmol/min at min 4 (from 4.45+/-0.03 to 3.3+/-0.25 ml/100 ml tissue) and reached its nadir at min 12 (from 4.45+/-0.03 to 1.6+/-0.08 ml/100 ml tissue, P<0.001). Our study documents a direct nongenomic effect of aldosterone on the resistance arteries in vivo in man. The rapid vasoconstrictive effect of aldosterone at physiological concentrations opens the way to investigations on the vascular role of this steroid in several disorders, such as hypertension, characterized by elevated peripheral vascular resistance.
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Affiliation(s)
- Paola Romagni
- Dipartimento di Fisiopatologia Medica, V Clinica Medica, Policlinico Umberto I, Facoltà di Medicina, Università di Roma La Sapienza, Viale del Policlinico, 00161 Rome, Italy
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Cardillo C, Campia U, Bryant MB, Panza JA. Increased activity of endogenous endothelin in patients with type II diabetes mellitus. Circulation 2002; 106:1783-7. [PMID: 12356630 DOI: 10.1161/01.cir.0000032260.01569.64] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Endothelial dysfunction may contribute to the risk of premature atherosclerosis in patients with diabetes. Endothelin (ET-1) may be involved in this process by activating smooth muscle cell mitogenesis and leukocyte adhesion. We sought to assess the activity of endogenous ET-1 in a group of patients with type II diabetes mellitus with the use of antagonists of ET-1 receptors. METHODS AND RESULTS Forearm blood flow (FBF) responses (strain gauge plethysmography) to intraarterial infusion of a selective blocker of ET(A) receptors (BQ-123) and, on a different occasion, to ET-1, were measured in 15 patients with diabetes and 12 healthy controls. In addition, 5 patients with diabetes received coinfusion of BQ-123 and BQ-788 (a selective blocker of ET(B) receptors). In normal subjects, BQ-123 did not significantly modify FBF from baseline (P=0.16). In contrast, BQ-123 administration resulted in a significant vasodilator response in patients with diabetes (P<0.001). Infusion of exogenous ET-1 resulted in lower vasoconstrictor responses in patients with diabetes than in controls (P=0.001), whereas the vasoconstrictor response to norepinephrine was similar in the 2 groups (P=0.78). In patients with diabetes, the vasodilator response to selective ET(A) blockade was not significantly modified by nonselective blockade of ET-1 receptors obtained by coinfusion of BQ-123 and BQ-788. CONCLUSIONS The activity of endogenous ET-1 on ET(A) receptors is enhanced in the resistance vessels of patients with diabetes, whereas their sensitivity to exogenous ET-1 is blunted. This abnormality may participate in the pathophysiology of vascular complications associated with diabetes.
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Affiliation(s)
- Carmine Cardillo
- Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md, USA
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Martin P, Ninio D, Krum H. Effect of endothelin blockade on basal and stimulated forearm blood flow in patients with essential hypertension. Hypertension 2002; 39:821-4. [PMID: 11897771 DOI: 10.1161/hy0302.105222] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Endothelin receptor antagonism lowers blood pressure in patients with essential hypertension, but the contribution of the endothelin system to increased vascular tone in these patients remains controversial. We used strain-gauge venous plethysmography to measure changes in basal and metabolically stimulated (peak reactive hyperemia [PRH]) forearm blood flow (FBF) induced by continuous intrabrachial infusion of SB 209670, a dual endothelin type A/endothelin type B receptor antagonist (ETRA) in 11 patients with hypertension and 12 healthy age-matched control subjects. In both groups, ETRA caused significant vasodilation (increase in FBF compared with baseline over the last 30 minutes of ETRA infusion: 75+/-12% in control subjects, 40+/-13% in hypertension patients; P<0.01 for both groups). By repeated-measures ANOVA, there was no greater increase in FBF after ETRA in hypertension patients compared with control subjects. In addition, FBF responses to PRH, expressed as percent change from baseline (prePRH), were similar in both groups (control subjects: preETRA, 1381+/-222%; during ETRA, 921+/-178%; and hypertension patients: preETRA, 1232+/-221%: during ETRA, 865+/-285%). We conclude that basal and stimulated vasodilation induced by short-term ETRA infusion in the forearm vasculature of hypertension patients is not increased compared with that of control subjects. An enhanced contribution of the endothelin system to vascular tone in hypertension patients could not be demonstrated using this experimental approach.
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Affiliation(s)
- Paul Martin
- Clinical Pharmacology Unit, Department of Medicine, Monash University, Alfred Hospital, Melbourne, Australia
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