1
|
Lahbib A, Ghodbane S, Sakly M, Abdelmelek H. Vitamins and glucose metabolism: The role of static magnetic fields. Int J Radiat Biol 2014; 90:1240-5. [DOI: 10.3109/09553002.2014.930537] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
2
|
Johnson FK, Johnson RA, Peyton KJ, Shebib AR, Durante W. Arginase promotes skeletal muscle arteriolar endothelial dysfunction in diabetic rats. Front Immunol 2013; 4:119. [PMID: 23730303 PMCID: PMC3657690 DOI: 10.3389/fimmu.2013.00119] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/04/2013] [Indexed: 11/18/2022] Open
Abstract
Endothelial dysfunction is a characteristic feature in diabetes that contributes to the development of vascular disease. Recently, arginase has been implicated in triggering endothelial dysfunction in diabetic patients and animals by competing with endothelial nitric oxide synthase for substrate l-arginine. While most studies have focused on the coronary circulation and large conduit blood vessels, the role of arginase in mediating diabetic endothelial dysfunction in other vascular beds has not been fully investigated. In the present study, we determined whether arginase contributes to endothelial dysfunction in skeletal muscle arterioles of diabetic rats. Diabetes was induced in male Sprague Dawley rats by streptozotocin injection. Four weeks after streptozotocin administration, blood glucose, glycated hemoglobin, and vascular arginase activity were significantly increased. In addition, a significant increase in arginase I and II mRNA expression was detected in gracilis muscle arterioles of diabetic rats compared to age-matched, vehicle control animals. To examine endothelial function, first-order gracilis muscle arterioles were isolated, cannulated in a pressure myograph system, exposed to graded levels of luminal flow, and internal vessel diameter measured. Increases in luminal flow (0–50 μL/min) caused progressive vasodilation in arterioles isolated from control, normoglycemic animals. However, flow-induced vasodilation was absent in arterioles obtained from streptozotocin-treated rats. Acute in vitro pretreatment of blood vessels with the arginase inhibitors Nω-hydroxy-nor-l-arginine or S-(2-boronoethyl)-l-cysteine restored flow-induced responses in arterioles from diabetic rats and abolished differences between diabetic and control animals. Similarly, acute in vitro pretreatment with l-arginine returned flow-mediated vasodilation in vessels from diabetic animals to that of control rats. In contrast, d-arginine failed to restore flow-induced dilation in arterioles isolated from diabetic animals. Administration of sodium nitroprusside resulted in a similar degree of dilation in arterioles isolated from control or diabetic rats. In conclusion, the present study identifies arginase as an essential mediator of skeletal muscle arteriolar endothelial dysfunction in diabetes. The ability of arginase to induce endothelial dysfunction in skeletal muscle arterioles may further compromise glucose utilization and facilitate the development of hypertension in diabetes.
Collapse
Affiliation(s)
- Fruzsina K Johnson
- Department of Physiology and Pharmacology, Lincoln Memorial University Harrogate, TN, USA
| | | | | | | | | |
Collapse
|
3
|
Puzantian H, Mosenkis A, Townsend RR. Vascular Compliance during Insulin Infusion and Oral Glucose Challenge. Artery Res 2013; 7:36-41. [PMID: 23997837 DOI: 10.1016/j.artres.2013.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Houry Puzantian
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Claire Fagin Hall, 418 Curie Blvd, Philadelphia, PA 19104, USA
| | | | | |
Collapse
|
4
|
Diabetes impairs arteriogenesis in the peripheral circulation: review of molecular mechanisms. Clin Sci (Lond) 2010; 119:225-38. [PMID: 20545627 DOI: 10.1042/cs20100082] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Patients suffering from both diabetes and PAD (peripheral arterial disease) are at risk of developing critical limb ischaemia and ulceration, and potentially requiring limb amputation. In addition, diabetes complicates surgical treatment of PAD and impairs arteriogenesis. Arteriogenesis is defined as the remodelling of pre-existing arterioles into conductance vessels to restore the perfusion distal to the occluded artery. Several strategies to promote arteriogenesis in the peripheral circulation have been devised, but the mechanisms through which diabetes impairs arteriogenesis are poorly understood. The present review provides an overview of the current literature on the deteriorating effects of diabetes on the key players in the arteriogenesis process. Diabetes affects arteriogenesis at a number of levels. First, it elevates vasomotor tone and attenuates sensing of shear stress and the response to vasodilatory stimuli, reducing the recruitment and dilatation of collateral arteries. Secondly, diabetes impairs the downstream signalling of monocytes, without decreasing monocyte attraction. In addition, EPC (endothelial progenitor cell) function is attenuated in diabetes. There is ample evidence that growth factor signalling is impaired in diabetic arteriogenesis. Although these defects could be restored in animal experiments, clinical results have been disappointing. Furthermore, the diabetes-induced impairment of eNOS (endothelial NO synthase) strongly affects outward remodelling, as NO signalling plays a key role in several remodelling processes. Finally, in the structural phase of arteriogenesis, diabetes impairs matrix turnover, smooth muscle cell proliferation and fibroblast migration. The review concludes with suggestions for new and more sophisticated therapeutic approaches for the diabetic population.
Collapse
|
5
|
Ozkiris A, Erkiliç K, Koç A, Mistik S. Effect of atorvastatin on ocular blood flow velocities in patients with diabetic retinopathy. Br J Ophthalmol 2007; 91:69-73. [PMID: 16973667 PMCID: PMC1857585 DOI: 10.1136/bjo.2006.098285] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2006] [Indexed: 01/02/2023]
Abstract
AIM To investigate blood flow velocities in the ophthalmic and central retinal arteries (CRAs) in patients with diabetic retinopathy before and after atorvastatin treatment. METHODS 45 patients with type 2 diabetes were included in this double-blind, placebo-controlled study. The patients with diabetes were divided into three subgroups: group 1 (n = 15) included patients with non-proliferative diabetic retinopathy (NPDR); group 2 (n = 15) had patients with proliferative diabetic retinopathy (PDR); and group 3 (n = 15; placebo group) included 8 patients with NPDR and 7 patients with PDR. The patients in groups 1 and 2 (atorvastatin group) received 10 mg atorvastatin daily for 10 weeks. Pre-treatment and post-treatment serum levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglyceride were recorded before and after treatment. Ocular blood flow velocities of the ophthalmic artery and CRA were evaluated by colour Doppler imaging before and after treatment in each group. RESULTS The baseline haemodynamic parameters were similar between atorvastatin and placebo groups (p>0.05 for both). Atorvastatin significantly decreased serum levels of total cholesterol, low-density lipoprotein cholesterol and triglycerides in groups 1 and 2 compared with pretreatment levels (p<0.001 for both). The mean peak systolic flow velocities (PSVs) of the ophthalmic artery in group 2, and the mean PSV and resistive indices of the CRA in groups 1 and 2 decreased significantly after atorvastatin treatment (p<0.05 for both), whereas the mean end diastolic flow velocity of the ophthalmic artery and CRA did not change (p>0.05). There was no significant difference in ocular blood flow velocities in the placebo group (p>0.05). CONCLUSION Atorvastatin may have a role in reducing diabetic retinal complications, with improvement in vascular resistance and decrease in the mean PSVs of the ophthalmic artery and CRA. However, further studies with large numbers of patients are needed to obtain the long-term results of this drug.
Collapse
Affiliation(s)
- A Ozkiris
- Medical Faculty, Erciyes University, Kayseri, Turkey.
| | | | | | | |
Collapse
|
6
|
Bagi Z, Toth E, Koller A, Kaley G. Microvascular dysfunction after transient high glucose is caused by superoxide-dependent reduction in the bioavailability of NO and BH(4). Am J Physiol Heart Circ Physiol 2004; 287:H626-33. [PMID: 15044190 DOI: 10.1152/ajpheart.00074.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We hypothesized that transient high-glucose concentration interferes with mediation by nitric oxide (NO) of flow-induced dilation (FID) of arterioles due to enhanced production of superoxide. In isolated, pressurized (80 mmHg) rat gracilis muscle arterioles ( approximately 130 microm) after transient high-glucose treatment (tHG; incubation with 30 mM glucose for 1 h), FID was reduced (maximum: control, 38 +/- 4%; after tHG, 17 +/- 3%), which was not further diminished by the NO synthase (NOS) inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME; 18 +/- 2%). Correspondingly, an enhanced polyethylene-glycol-SOD (PEG-SOD)-sensitive superoxide production was detected after tHG in carotid arteries by dihydroethydine (DHE) staining. Presence of PEG-SOD during tHG prevented the reduction of FID (41 +/- 3%), which could be inhibited by l-NAME (20 +/- 4%). Administration of PEG-SOD after tHG did not prevent the reduction of FID (22 +/- 3%). Sepiapterin, a precursor of the NO synthase cofactor tetrahydrobiopterin (BH(4)), administered during tHG did not prevent the reduction of FID (maximum, 15 +/- 5%); however, it restored FID when administered after tHG (32 +/- 4%). Furthermore, inhibition of either glycolysis by 2-deoxyglucose or mitochondrial complex II by 2-thenoyltrifluoroacetone reduced the tHG-induced DHE-detectable enhanced superoxide production in carotid arteries and prevented FID reduction in arterioles (39 +/- 5 and 35 +/- 2%). Collectively, these findings suggest that in skeletal muscle arterioles, a transient elevation of glucose via its increased metabolism, elicits enhanced production of superoxide, which decreases the bioavailability of NO and the level of the NOS cofactor BH(4), resulting in a reduction of FID mediated by NO.
Collapse
Affiliation(s)
- Zsolt Bagi
- Department of Physiology, New York Medical College, Valhalla, NY 10595, USA
| | | | | | | |
Collapse
|
7
|
Cotter MA, Cameron NE. Effect of the NAD(P)H oxidase inhibitor, apocynin, on peripheral nerve perfusion and function in diabetic rats. Life Sci 2003; 73:1813-24. [PMID: 12888120 DOI: 10.1016/s0024-3205(03)00508-3] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Upregulation of vascular NAD(P)H oxidase has been considered an important source for elevated levels of reactive oxygen species that contribute to several cardiovascular disease states, including the vascular complications of diabetes mellitus. Previous studies have shown that treatment with antioxidants corrects impaired nerve function and blood flow in diabetic rats. The aim was to assess the degree of involvement of NAD(P)H oxidase in experimental diabetic neuropathy. To this end, after 6 weeks of untreated streptozotocin-diabetes, rats were treated for 2 weeks with the NAD(P)H oxidase, apocynin. Two high doses (15 and 100 mg/kg) were used to ensure that maximal effects were registered. Diabetes caused a 20% reduction in sciatic nerve motor conduction velocity, and a 14% deficit for sensory saphenous nerve. Apocynin treatment corrected these defects by 32% and 48%, respectively: there were no significant differences between the effects of the 2 doses. Sciatic nerve nutritive endoneurial perfusion was measured by hydrogen clearance microelectrode polarography. Blood flow and vascular conductance were 47% and 40% reduced by diabetes, respectively. Both doses of apocynin had similar effects, correcting the blood flow deficit by 31% and conductance by 47%. Thus, the data show that NAD(P)H oxidase contributes to the neurovascular deficits in diabetic rats. While only accounting for part of the elevated reactive oxygen species production in diabetes, this mechanism could provide a novel therapeutic candidate for further investigation in diabetic neuropathy and vasculopathy.
Collapse
Affiliation(s)
- M A Cotter
- Department of Biomedical Sciences, Institute of Medical Sciences, Aberdeen University, Foresterhill, AB25 2ZD Scotland, Aberdeen, UK
| | | |
Collapse
|
8
|
Bagi Z, Koller A. Lack of nitric oxide mediation of flow-dependent arteriolar dilation in type I diabetes is restored by sepiapterin. J Vasc Res 2003; 40:47-57. [PMID: 12644725 DOI: 10.1159/000068938] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2002] [Accepted: 10/10/2002] [Indexed: 11/19/2022] Open
Abstract
The mechanisms leading to microangiopathy in diabetes mellitus have still not been clearly elucidated. We hypothesized that type I diabetes mellitus affects the endothelium and alters flow-dependent dilation of arterioles, an important mechanism involved in local regulation of blood flow. Isolated, pressurized gracilis muscle arterioles (inside diameter approximately 150 microm at 80 mm Hg) from rats with streptozotocin (STZ)-induced diabetes mellitus exhibited reduced dilations induced by increases in perfusate flow compared to those of normal rats (plasma glucose: 25.7 +/- 0.7 vs. 6.4 +/- 0.5 mmol/l; maximum increase in diameter: 15 +/- 4 vs. 31+/- 3 microm, p < 0.05). In control arterioles, both nitric oxide (NO) and prostaglandins mediated the flow-dependent dilation, whereas flow-induced dilations of diabetic arterioles were unaffected by N(omega)-nitro-L-arginine methyl ester (L-NAME) and were abolished by indomethacin. Sepiapterin - precursor of the endothelial NO synthase (eNOS) cofactor tetrahydrobiopterin (BH(4)) - restored the L-NAME-sensitive portion of flow-dependent dilations of diabetic arterioles. Furthermore, depletion of BH(4) by 2,4-diamino-6-hydroxypyrimidine (DAHP) in control arterioles also resulted in reduced flow-dependent dilations, which were restored by intraluminal sepiapterin [but not with superoxide dismutase (SOD) plus catalase (CAT) (SOD+CAT)] and then could be inhibited by L-NAME. Dilations induced by the NO donor sodium nitroprusside (SNP) were unaffected by L-NAME in diabetes mellitus arterioles or when eNOS was activated by intraluminal flow in DAHP-treated arterioles (with or without SOD+CAT). In contrast, pyrogallol (known to produce reactive oxygen species) substantially reduced acetylcholine- and SNP-induced dilation in a SOD+CAT-reversible manner. Collectively, these findings suggest that in diabetic arterioles, due to the reduced bioavailability of BH(4), the synthesis of NO by eNOS is limited, resulting in a reduced flow-induced dilation, a mechanism that may also be responsible for the development of diabetic microangiopathy and exacerbation of other vascular diseases.
Collapse
Affiliation(s)
- Zsolt Bagi
- Department of Pathophysiology, Semmelweis University, Budapest, Hungary
| | | |
Collapse
|
9
|
Jack AM, Keegan A, Cotter MA, Cameron NE. Effects of diabetes and evening primrose oil treatment on responses of aorta, corpus cavernosum and mesenteric vasculature in rats. Life Sci 2002; 71:1863-77. [PMID: 12175702 DOI: 10.1016/s0024-3205(02)01912-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Diabetes causes endothelial dysfunction, with deleterious effects on nitric oxide (NO) mediated vasodilatation. However, in many vessels other local vasodilators such as endothelium-derived hyperpolarizing factor (EDHF), prostacyclin, epoxides or endocannabinoids are also important. Several of these factors may be derived from omega-6 essential fatty acids via arachidonate metabolism. Diabetes inhibits this pathway, a defect that may be bypassed by diets enriched with omega-6 gamma-linolenic acid-containing oils such as evening primrose oil (EPO). The aim was to examine the effects of preventive EPO treatment on endothelium-dependent and neurally mediated vasorelaxation. Diabetes was induced by streptozotocin in rats; duration was 8 weeks. Vascular responses were examined in vitro on thoracic aorta, corpus cavernosum and perfused mesenteric bed preparations. Diabetes caused 25% and 35% deficits, respectively, in aorta and corpus cavernosum NO-mediated endothelium-dependent relaxation to acetylcholine that were largely unaffected by EPO treatment. Moreover, a 44% reduction in maximum corpus cavernosum vasorelaxation to nitrergic nerve stimulation was not prevented by EPO. However, for the mesenteric vascular bed, a 29% diminution of responses to acetylcholine, mediated by both NO and EDHF, was 84% attenuated by EPO treatment. When the EDHF component was isolated during NO synthase inhibition, a 76% diabetic deficit was noted. This was completely prevented by EPO treatment, which also caused supernormal EDHF responses in nondiabetic rats. EPO treatment prevented the development of deficits in endothelium-dependent relaxation in diabetic rats. Effects were particularly marked on the resistance vessel EDHF system, which may have potential therapeutic relevance for diabetic microvascular complications.
Collapse
Affiliation(s)
- Alison M Jack
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | | | | | | |
Collapse
|
10
|
Savvidou MD, Geerts L, Nicolaides KH. Impaired vascular reactivity in pregnant women with insulin-dependent diabetes mellitus. Am J Obstet Gynecol 2002; 186:84-8. [PMID: 11810090 DOI: 10.1067/mob.2002.119111] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the vascular function of pregnant women with insulin-dependent diabetes mellitus, using a noninvasive method. STUDY DESIGN This was a cross-sectional study that examined vascular function, which was assessed by flow-mediated dilatation of the brachial artery, in 37 pregnant women with insulin-dependent diabetes mellitus and in 37 healthy pregnant women at 20 weeks of gestation. The control of diabetes was also assessed by the measurement of glycosylated hemoglobin. Data were analyzed by 2-sided unpaired t test and multivariate regression analysis. RESULTS In the pregnant women with insulin-dependent diabetes mellitus, flow-mediated dilatation of the brachial artery was significantly lower than in healthy pregnant women (6.43% +/- 3.66% vs 9.43% +/- 3.69%, respectively; P =.0008). This difference was apparent even after an adjustment was made for blood vessel diameter, which was different between the 2 populations (P =.01). Flow-mediated dilatation in diabetic women was significantly correlated with the duration of diabetes (P =.01) but not with the levels of glycosylated hemoglobin. CONCLUSION Maternal insulin-dependent diabetes mellitus is associated with an impaired vasodilatory response to a blood flow stimulus. This vascular dysfunction is associated with the duration of the diabetes.
Collapse
Affiliation(s)
- Makrina D Savvidou
- Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, Denmark Hill, London, United Kingdom
| | | | | |
Collapse
|
11
|
Ruhe RC, McDonald RB. Use of antioxidant nutrients in the prevention and treatment of type 2 diabetes. J Am Coll Nutr 2001; 20:363S-369S; discussion 381S-383S. [PMID: 11603645 DOI: 10.1080/07315724.2001.10719169] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Type 2 diabetes, or non-insulin dependent diabetes mellitus (NIDDM), is increasingly common throughout the world. The World Health Organization has predicted that between 1997 and 2025, the number of diabetics will double from 143 million to about 300 million. The incidence of NIDDM is highest in economically developed nations, particularly the U.S., where approximately 6.5% of the population (17 million people) have either diagnosed or undiagnosed diabetes. The two most important factors contributing to the development of NIDDM are obesity and physical inactivity. The leading cause of mortality and morbidity in people with NIDDM is cardiovascular disease caused by macro- and microvascular degeneration. Current therapies for NIDDM focus primarily on weight reduction. Indeed, several investigations indicate that 65% to 75% of cases of diabetes in Caucasians could be avoided if individuals in this subgroup did not exceed their ideal weight. The success of this approach has been, at best, modest. An alternate approach to the control of Type 2 diabetes is to arrest the progress of the pathology until a cure has been found. To this end, some investigators suggest that dietary antioxidants may be of value. Several studies in humans and laboratory animals with NIDDM indicate that vitamin E and lipoic acid supplements lessen the impact of oxidative damage caused by dysregulation of glucose metabolism. In this brief review, we discuss the incidence, etiology, and current therapies for NIDDM and further explore the usefulness of dietary antioxidants in treating this disorder.
Collapse
Affiliation(s)
- R C Ruhe
- Department of Nutrition, University of California, Davis 95616-8669, USA
| | | |
Collapse
|
12
|
Faber LL, Porret CA, Meister JJ, Stergiopulos N. In vitro diameter response of rat femoral artery to flow in the presence and absence of endothelium. J Biomech 2001; 34:1023-30. [PMID: 11448694 DOI: 10.1016/s0021-9290(01)00059-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have examined the diameter response of rat femoral artery segments in the presence and absence of endothelium to changes in flow rate. The segments were isolated, mounted on microcannulae, maintained at 37 degrees C, and perfused at 90 mmHg with Tyrode's solution. The external arterial diameter was measured using video-microscopy. The mean control diameter was 741+/-22 microm (mean+/-SEM,n=7). The arteries were preconstricted to 75+/-1% of the control diameter with a superfusion of 1 microM norepinephrine (NE). Endothelial function was verified by perfusion of 1 micro;M acetylcholine (ACh). Two different flow protocols were employed: step changes in flow (n=7) and low-frequency sinusoidal flow changes (0.01Hz<f<0.05Hz,n=3). The endothelium was then removed by perfusion of the artery with 0.3% CHAPS (n=7) and the flow protocol repeated. All arteries contracted with increasing flow. For rapid step changes in flow, contractions and relaxations were modelled with an exponential fit where characteristic time constants were 34+/-2 and 40+/-3s, respectively (functional endothelium) and 35+/-2 and 37+/-2s, respectively (non-functional endothelium). The time constants in the presence and absence of endothelium were not significantly different (paired t-test, p>0.05). Sinusoidal flow oscillations resulted in sinusoidal diameter oscillations, whose amplitude and phase lag were inversely proportional to the frequency of the flow oscillations. A first-order low-pass filter, with a time constant of 28+/-3 and 30+/-5s for arteries with and without functional endothelium, respectively, was used to describe the relation between oscillatory flow and diameter. The response of the rat femoral arteries to changes in flow was not found to be different whether the endothelium was intact or removed.
Collapse
Affiliation(s)
- L L Faber
- Biomedical Engineering Laboratory, Swiss Federal Institute of Technology, PSE-Ecublens 1015, Lausanne, Switzerland
| | | | | | | |
Collapse
|
13
|
Savage T, Tribe RM, Yaqoob MM. Flow induces dilatation in the femoral artery of uraemic rats but constriction in control rats. Nephrol Dial Transplant 2001; 16:1156-62. [PMID: 11390714 DOI: 10.1093/ndt/16.6.1156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Pressure and flow are recognized as important modulators of vascular tone. In mildly uraemic rats, myogenic tone is increased in the femoral artery in the absence of hypertension compared with healthy control rats, but the effect of flow in the same experimental model remains unknown. SUBJECTS AND METHODS Twelve male Wistar rats were rendered uraemic (U) by 5/6th nephrectomy or were concurrently sham operated as controls (C). After 8 weeks, isolated femoral arteries were mounted on a flow myograph, pressurized at 80 mmHg, and constricted by 40-50% of the lumen internal diameter (i.d.) by L-phenylephrine (1-10 micromol/l). Flow was initiated (0-207 microl/min) in six steps every 5 min and changes in i.d. recorded. N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (0.1 mmol/l) and 1H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) (1 micromol/l) were applied extraluminally and the flow protocol repeated. RESULTS The baseline pre-constricted at 80 mmHg i.d. was significantly smaller in the U (U 255+/-21 microm vs C 365+/-36 microm, P<0.03). At all steps, flow elicited a dilatation in the U and a constriction in the C (U+ 24+/-8% vs C-17+/-5%, P<0.01). When L-NAME and ODQ were applied, a significant basal reduction in i.d. was observed in the C only (C 365+/-36 microm vs C+ L-NAME & ODQ 182+/-18 microm, P<0.01; U 255+/- 21 microm vs U+L-NAME & ODQ 240+/-11 microm, P=n.s.). Furthermore, in the U there was no significant blunting to dilatation during flow (+9+/-4%). CONCLUSIONS Flow elicited a constriction in controls, but a marked dilatation in uraemic roots which was not entirely nitric oxide dependent. These results suggest that other mediators such as prostacyclin or endothelium-dependent hyperpolarizing factor, or changes in the vascular smooth muscle may contribute to flow-induced dilatation in mild experimental uraemia.
Collapse
Affiliation(s)
- T Savage
- Anthony Raine Research Laboratories, St Bartholomew's Hospital, Guys, Kings & St Thomas' Hospitals, London, UK
| | | | | |
Collapse
|
14
|
Rösen P, Nawroth PP, King G, Möller W, Tritschler HJ, Packer L. The role of oxidative stress in the onset and progression of diabetes and its complications: a summary of a Congress Series sponsored by UNESCO-MCBN, the American Diabetes Association and the German Diabetes Society. Diabetes Metab Res Rev 2001; 17:189-212. [PMID: 11424232 DOI: 10.1002/dmrr.196] [Citation(s) in RCA: 627] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review summarises the results and discussions of an UNESCO-MCBN supported symposium on oxidative stress and its role in the onset and progression of diabetes. There is convincing experimental and clinical evidence that the generation of reactive oxygen species (ROI) is increased in both types of diabetes and that the onset of diabetes is closely associated with oxidative stress. Nevertheless there is controversy about which markers of oxidative stress are most reliable and suitable for clinical practice. There are various mechanisms that contribute to the formation of ROI. It is generally accepted that vascular cells and especially the endothelium become one major source of ROI. An important role of oxidative stress for the development of vascular and neurological complications is suggested by experimental and clinical studies. The precise mechanisms by which oxidative stress may accelerate the development of complications in diabetes are only partly known. There is however evidence for a role of protein kinase C, advanced glycation end products (AGE) and activation of transcription factors such as NF kappa B, but the exact signalling pathways and the interactions with ROI remain a matter of discussion. Additionally, results of very recent studies suggest a role for ROI in the development of insulin resistance. ROI interfere with insulin signalling at various levels and are able to inhibit the translocation of GLUT4 in the plasma membrane. Evidence for a protective effect of antioxidants has been presented in experimental studies, but conclusive evidence from patient studies is missing. Large-scale clinical trials such as the DCCT Study or the UKPDS Study are needed to evaluate the long-term effects of antioxidants in diabetic patients and their potential to reduce the medical and socio-economic burden of diabetes and its complications.
Collapse
Affiliation(s)
- P Rösen
- Deutsches Diabetesforschungsinstitut, Düsseldorf, Germany.
| | | | | | | | | | | |
Collapse
|
15
|
Barbieri M, Rizzo MR, Manzella D, Paolisso G. Age-related insulin resistance: is it an obligatory finding? The lesson from healthy centenarians. Diabetes Metab Res Rev 2001; 17:19-26. [PMID: 11241888 DOI: 10.1002/dmrr.178] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
It is widely known that advancing age is associated with impaired glucose handling. A unifying hypothesis explaining the relationship between aging and insulin resistance might encompass four main pathways, namely: (a) anthropometric changes (relative and absolute increase in body fat combined with a decline in fat free mass) which could be the anatomic substrate for explaining the reduction in active metabolic tissue; (b) environmental causes, mainly diet style and physical activity; (c) neuro-hormonal variations [decline in plasma dehydroepandrosterone sulphate (DHEAS) and IGF-1]; and finally (d) the rise in oxidative stress. Indeed previous studies have also investigated the occurrence and the degree of insulin resistance in healthy centenarians. Such data demonstrated that age-related insulin resistance is not an obligatory finding in the elderly and that healthy centenarians have a preserved insulin action compared to aged subjects. Why insulin action is preserved in centenarians is still not known. Nevertheless, a possible approach to the question is to outline the centenarians' anthropometric, endocrine and metabolic characteristics in order to design a clinical picture of such metabolic "successful aging". According to the remodeling theory of age, the preserved insulin action in centenarians might be the net result of the continuous adaptation of the body to the deleterious changes that occur over time. Nevertheless, only future longitudinal studies specifically designed to investigate the relationship between extreme old age and degree of insulin sensitivity will provide a conclusive answer with regard to the pathophysiology of adaptive metabolic changes occurring in the elderly.
Collapse
Affiliation(s)
- M Barbieri
- Department of Geriatric Medicine and Metabolic Diseases, II University of Naples, I-80138 Naples, Italy
| | | | | | | |
Collapse
|
16
|
Mullen MJ, Wright D, Donald AE, Thorne S, Thomson H, Deanfield JE. Atorvastatin but not L-arginine improves endothelial function in type I diabetes mellitus: a double-blind study. J Am Coll Cardiol 2000; 36:410-6. [PMID: 10933350 DOI: 10.1016/s0735-1097(00)00743-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVES We sought to determine the effects of oral L-arginine and the hexamethylglutaryl coenzyme A reductase inhibitor atorvastatin on endothelial function in young patients with type I diabetes mellitus (DM). BACKGROUND Endothelial dysfunction, a key early event in atherosclerosis, occurs in young patients with type I DM, and its reversal may benefit the progression of vascular disease. Cholesterol reduction in L-arginine improve endothelial function in nondiabetic subjects, but their effect in patients with type I DM is unknown. METHODS In a double-blind, 2x2 factorial study, we investigated the effect of L-arginine (7 g twice daily) and atorvastatin (40 mg/day) on conduit artery vascular function in 84 normocholesterolemic young adults (mean+/-SD: age 34 years [range 18 to 46], low density lipoprotein [LDL] cholesterol 2.96+/-0.89 mmol/liter) with type I DM. Brachial artery dilation to flow (flow-mediated dilation [FMD]) and to the direct smooth muscle dilator glyceryl trinitrate (GTN) were assessed noninvasively using high resolution ultrasound at baseline and after six weeks of treatment. RESULTS Atorvastatin resulted in a 48+/-10% decrease in serum LDL cholesterol levels, whereas L-arginine levels increased by 247+/-141% after L-arginine therapy. By analysis of covariance, treatment with atorvastatin resulted in a significant increase in FMD (p = 0.018. L-Arginine therapy had no significant effect on endothelial function, and there was no significant change in dilation to GTN after either intervention. CONCLUSIONS In young patients with type I DM, improvement in endothelial dysfunction can be demonstrated after just six weeks of treatment with atorvastatin. In contrast to studies of hypercholesterolemia, however, L-arginine had no benefit. Treatment with atorvastatin at an early stage may have an impact on the progression of atherosclerosis in these high risk patients.
Collapse
Affiliation(s)
- M J Mullen
- Vascular Physiology Unit, Great Ormond Street Hospital for Children, London, United Kingdom.
| | | | | | | | | | | |
Collapse
|
17
|
Terata K, Coppey LJ, Davidson EP, Dunlap JA, Gutterman DD, Yorek MA. Acetylcholine-induced arteriolar dilation is reduced in streptozotocin-induced diabetic rats with motor nerve dysfunction. Br J Pharmacol 1999; 128:837-43. [PMID: 10516670 PMCID: PMC1571695 DOI: 10.1038/sj.bjp.0702856] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
1. Diabetes mellitus produces marked abnormalities in motor nerve conduction, but the mechanism is not clear. In the present study we hypothesized that in the streptozotocin (STZ)-induced diabetic rat impaired vasodilator function is associated with reduced endoneural blood flow (EBF) which may contribute to nerve dysfunction. 2. We examined whether diabetes-induced reductions in sciatic nerve conduction velocity and EBF were associated with impaired endothelium-dependent dilation in adjacent arterioles. We measured motor nerve conduction velocity (MNCV) in the sciatic nerve using a non-invasive procedure, and sciatic nerve nutritive blood flow using microelectrode polarography and hydrogen clearance. In vitro videomicroscopy was used to quantify arteriolar diameter responses to dilator agonists in arterioles overlying the sciatic nerve. 3. MNCV and EBF in 4-week-STZ-induced diabetic rats were decreased by 22% and 49% respectively. Arterioles were constricted with U46619 and dilation to acetylcholine (ACh), aprikalim, or sodium nitroprusside (SNP) examined. All agonists elicited dose-dependent dilation in control and diabetic rats, although ACh-induced dilation was significantly reduced in diabetic rats. Treating vessels from normal or diabetic rats with indomethacin (INDO) alone did not significantly affect ACh-induced relaxation. However, ACh-induced vasodilation was significantly reduced by treatment with KCl or Nomega-nitro-L-arginine (LNNA) alone. Combining LNNA and KCl further reduced ACh-induced dilation in these vessels. 4. Diabetes causes vasodilator dysfunction in a microvascular bed that provides circulation to the sciatic nerve. These studies imply that ACh-induced dilation in these vessels is mediated by multiple mechanisms that may include the endothelial-dependent production of nitric oxide and endothelial-derived hyperpolarizing factor. This impaired vascular response is associated with neural dysfunction.
Collapse
Affiliation(s)
- K Terata
- Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, Indiana, IA, 52246, U.S.A
| | - L J Coppey
- Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, Indiana, IA, 52246, U.S.A
| | - E P Davidson
- Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, Indiana, IA, 52246, U.S.A
| | - J A Dunlap
- Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, Indiana, IA, 52246, U.S.A
| | - D D Gutterman
- Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, Indiana, IA, 52246, U.S.A
| | - M A Yorek
- Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, Indiana, IA, 52246, U.S.A
- Author for correspondence:
| |
Collapse
|
18
|
Paolisso G, Tagliamonte MR, Rizzo MR, Giugliano D. Advancing age and insulin resistance: new facts about an ancient history. Eur J Clin Invest 1999; 29:758-69. [PMID: 10469164 DOI: 10.1046/j.1365-2362.1999.00522.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The relationship between advancing age and insulin resistance is widely known, but the cause(s) of such association are less well understood. Age-related changes in anthropometric characteristics and environmental factors (changes in diet habits and decline in physical activity) have been hypothesized as being among the main causes. More recently, the role of plasma insulin-like growth factor I (IGF-I), dehydroepiandrosterone sulphate (DHEAS) and tumour necrosis factor alpha (TNF-alpha) concentrations as well as the degree of oxidative stress have also been evaluated. As far as the anthropometric changes are concerned, a decline in fat-free mass and a relative or absolute increase in fat mass are common findings in aged subjects. Such changes are combined with a decline in plasma DHEAS and IGF-I concentration and a rise in plasma TNF-alpha concentrations and oxidative stress, which, in turn, may interact with the anthropometric changes determining the worsening in insulin-mediated glucose uptake. Finally, age-related environmental factors (changes in diet quality and decline in the degree of physical activity) might be a common factor allowing anthropometric factors and age-related remodelling to accelerate their negative impact on insulin action.
Collapse
Affiliation(s)
- G Paolisso
- Department of Geriatric Medicine and Metabolic Diseases - II University of Naples, Italy.
| | | | | | | |
Collapse
|
19
|
Izzard AS, Heagerty AM. Impaired flow-dependent dilatation in distal mesenteric arteries from the spontaneously hypertensive rat. J Physiol 1999; 518:239-45. [PMID: 10373705 PMCID: PMC2269414 DOI: 10.1111/j.1469-7793.1999.0239r.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. The aim of the study was to examine the hypothesis that flow-dependent dilatation is impaired in distal mesenteric arteries from adult spontaneously hypertensive rats (SHR) compared with normotensive Wistar-Kyoto rat (WKY) controls and to assess the role of nitric oxide (NO). 2. Arterial segments were cannulated, pressurized to 80 mmHg and allowed to develop spontaneous myogenic tone. Flow was increased incrementally in vessels from both strains and responses were also assessed before and after incubation with the NO synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME). Responses to flow in control vessels were also assessed before and after intraluminal perfusion with antibody-complement to disrupt the endothelium. 3. At a flow rate of 5 microliter min-1, arteries from the WKY dilated significantly (22 +/- 5%, P < 0.01, n = 29) compared with the diameter at zero flow, whereas arteries from the SHR did not (4 +/- 4%, n.s., n = 16). Incubation with L-NAME had no inhibitory effect on the responses to flow in either rat strain. In control arteries, antibody-complement treatment abolished the dilatation in response to both flow and acetylcholine (ACh, 1 microM). 4. We conclude that flow-dependent dilatation is impaired in distal mesenteric arteries from adult SHR compared with WKY controls. Furthermore, flow-dependent dilatation is endothelium dependent, but L-NAME insensitive, thus excluding the NO pathway in this abnormality. Impaired flow-dependent dilatation may contribute to the increased peripheral resistance in hypertension.
Collapse
Affiliation(s)
- A S Izzard
- University Department of Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK.
| | | |
Collapse
|
20
|
Renaudin C, Michoud E, Lagarde M, Wiernsperger N. Impaired microvascular responses to acute hyperglycemia in type I diabetic rats. J Diabetes Complications 1999; 13:39-44. [PMID: 10232708 DOI: 10.1016/s1056-8727(98)00018-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Abnormal reactivity of resistance vasculature may induce long-term alterations in regional hemodynamics, contributing to the pathogenesis of diabetic microangiopathy. The purpose of this study was to examine the responses of microvessels to a hyperglycemic episode aimed at mimicking a physiological stimulus such as the postprandial state. This study is the first to report the direct, in situ, visualization of this situation by intravital microscopy in the skeletal muscle of diabetic rat and is particularly interesting as it applies to an iterative, physiological stimulus. The study was conducted in 5-month-old rats, either nondiabetic (ND) or rendered diabetic (D) for 12 weeks (streptozotocin, 60 mg/kg, i.v.). Intravital microscopy was used to examine diameter and vasomotion changes in precapillary arterioles (< 20 microm) in the spinotrapezius muscle of fasted, anesthetized rats, before and up to 60 min after infusion of glucose or isotonic saline. After intravenous glucose infusion, a precapillary arteriolar vasoconstriction associated with an increase in the number of arterioles presenting vasomotion were seen in ND rats. In contrast, no modification in either parameter was observed in D rats. Our results indicate that, microvessels react to acute changes in the metabolic environment such as induced by elevation of plasma glucose. There was a complete loss of reactivity (vasoconstriction and vasomotion) of precapillary arterioles to superimposed hyperglycemia in D rats. According to the "hemodynamic hypothesis", this impaired vasoconstriction could result in hyperperfusion of microvessels and subsequent microvascular damages which might contribute to the development of diabetic microangiopathy.
Collapse
Affiliation(s)
- C Renaudin
- Diabetic Microangiopathy Research Unit, Lipha-INSERM U 352, Villeurbanne, France
| | | | | | | |
Collapse
|