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Mackenzie RWA, Watt P. A Molecular and Whole Body Insight of the Mechanisms Surrounding Glucose Disposal and Insulin Resistance with Hypoxic Treatment in Skeletal Muscle. J Diabetes Res 2016; 2016:6934937. [PMID: 27274997 PMCID: PMC4871980 DOI: 10.1155/2016/6934937] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 04/04/2016] [Accepted: 04/12/2016] [Indexed: 12/22/2022] Open
Abstract
Although the mechanisms are largely unidentified, the chronic or intermittent hypoxic patterns occurring with respiratory diseases, such as chronic pulmonary disease or obstructive sleep apnea (OSA) and obesity, are commonly associated with glucose intolerance. Indeed, hypoxia has been widely implicated in the development of insulin resistance either via the direct action on insulin receptor substrate (IRS) and protein kinase B (PKB/Akt) or indirectly through adipose tissue expansion and systemic inflammation. Yet hypoxia is also known to encourage glucose transport using insulin-dependent mechanisms, largely reliant on the metabolic master switch, 5' AMP-activated protein kinase (AMPK). In addition, hypoxic exposure has been shown to improve glucose control in type 2 diabetics. The literature surrounding hypoxia-induced changes to glycemic control appears to be confusing and conflicting. How is it that the same stress can seemingly cause insulin resistance while increasing glucose uptake? There is little doubt that acute hypoxia increases glucose metabolism in skeletal muscle and does so using the same pathway as muscle contraction. The purpose of this review paper is to provide an insight into the mechanisms underpinning the observed effects and to open up discussions around the conflicting data surrounding hypoxia and glucose control.
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Affiliation(s)
- R. W. A. Mackenzie
- Department of Life Science, Whitelands College, University of Roehampton, Holybourne Avenue, London SW15 4DJ, UK
- *R. W. A. Mackenzie:
| | - P. Watt
- University of Brighton, Hillbrow, Denton Road, Eastbourne BN20 7SP, UK
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Goto K, Morishima T, Kurobe K, Huang Z, Ogita F. Augmented Carbohydrate Oxidation under Moderate Hypobaric Hypoxia Equivalent to Simulated Altitude of 2500 m. TOHOKU J EXP MED 2015; 236:163-8. [DOI: 10.1620/tjem.236.163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Kazushige Goto
- Faculty of Sport and Health Science, Ritsumeikan University
| | | | - Kazumichi Kurobe
- Faculty of Business, Sports Management Course, Hannan University
| | - Zhong Huang
- Department of Sports Sciences, Japan Institute of Sports Sciences
| | - Futoshi Ogita
- Department of Sports and Life Science, National Institute of Fitness and Sports in Kanoya
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Successive exposure to moderate hypoxia does not affect glucose metabolism and substrate oxidation in young healthy men. SPRINGERPLUS 2014; 3:370. [PMID: 25089253 PMCID: PMC4117865 DOI: 10.1186/2193-1801-3-370] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 07/03/2014] [Indexed: 12/03/2022]
Abstract
Introduction Exposure to hypoxia has been suggested to acutely alter glucose regulation. However, the effects of successive exposure to moderate hypoxia on postprandial glucose regulation and substrate oxidation pattern after multiple meals have not been elucidated. Purpose We examined the effects of successive exposure to moderate hypoxia on metabolic responses and substrate oxidation pattern. Methods Eight healthy men (21.0 ± 0.6 yrs, 173 ± 2.3 cm, 70.6 ± 5.0 kg, 23.4 ± 1.1 kg/m2) completed two experimental trials on separate days: a rest trial under normoxic conditions (FiO2 = 20.9%) and a rest trial under hypoxic conditions (FiO2 = 15.0%). Experimental trials were performed over 7 h in an environmental chamber. Blood and respiratory gas samples were collected over 7 h. Standard meals were provided 1 h (745 kcal) and 4 h (731 kcal) after entering the chamber. Results Although each meal significantly increased blood glucose and serum insulin concentrations (P < 0.05), these responses did not differ significantly between the trials. There were no significant differences in areas under the curves for glucose or insulin concentrations over 7 h between the trials. No significant differences were observed in blood lactate, serum cortisol, free fatty acid, or glycerol concentrations over 7 h between the trials. The oxygen consumption (
) and carbon dioxide production (
) 3 h after entering the chamber were significantly higher in the hypoxic trial than in the normoxic trial (P < 0.05). However, the differences did not affect respiratory exchange ratio (RER). The average values of
,
, and RER did not differ between the trials. Conclusion Seven hours of moderate hypoxia did not alter postprandial glucose responses or substrate oxidation in young healthy men.
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Yin T, Li NF, Heizhati M, Zhang J, Zhang J, Zhou L, Chang G. Association of glucose transporter 4 genetic polymorphisms with obstructive sleep apnea syndrome in Han Chinese general population: a cross-section study. Lipids Health Dis 2014; 13:12. [PMID: 24410986 PMCID: PMC3910679 DOI: 10.1186/1476-511x-13-12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 01/07/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Obstructive sleep apnea syndrome (OSAS) is strongly associated with the increasing prevalence of cerebrovascular events and metabolic syndrome. A growing number of studies have shown OSAS is an independent factor for insulin resistance, glucose intolerance and type2 diabetes. However, relationship of OSAS with dysglycemia is complex and still remains poorly understood. Glucose transporter 4 (GLUT4) gene is Human and rodents' main glucose transporter sensitive to insulin, and therefore confirmation of candidate gene polymorphisms and association with OSAS is needed. Aim of our study was to assess whether GLUT4 gene polymorphisms are associated with OSAS. METHODS Patients hospitalized at People's Hospital of Xinjiang were selected from January to December 2010. A total of 568 Han subjects who possibly exist OSAS base on a history and physical examination were completed the polysomnography, 412of whom (72.5%) were diagnosed with OSAS, and 156 individuals were confirmed without OSAS (27.5%). 96 severe OSAS patients chosen from OSAS were used for DNA sequencing in functional domain. Blood samples were collected from all subjects and genotyping was performed on DNA extracted from blood cells. RESULTS We performed GLUT4 genome sequencing, found 4 mutated sites. And finally selected three mutated sites such as rs5415, rs4517 and rs5435, according to principle of linkage disequilibrium (r2 > 0.8) and minimum gene allele frequency > 5%. All SNPs satisfied HEW (P > 0.05). Our study demonstrated a significant association of GLUT4 SNPrs5417 allele with OSAS, compared with controls (P < 0.05). Haplotype H1 (TCC) and H3 (CCC) defined as SNPrs5415, rs4517 and rs5435 are marginally associated with OSAS (P < 0.05). Frequencies of C haplotype of rs5417 in OSAS were higher than in controls. After adjustment for confounding factors, (AC + AA) genotype significantly reduces prevalence of OSAS, compared with CC genotype. Level of awake blood oxygen and lowest blood oxygen of (AA + AC) genotype was significantly superior to those of CC genotype. CONCLUSIONS Our study demonstrates GLUT4 gene SNPrs5417 is associated with OSAS in hypertensive population. Carriers of AA + AC have less prevalence of obstructive sleep apnea syndrome than that of CC carriers.
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Affiliation(s)
- Ting Yin
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
| | - Nan fang Li
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
| | - Mulalibieke Heizhati
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
| | - Juhong Zhang
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
| | - Jingjing Zhang
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
| | - Ling Zhou
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
| | - Guijuan Chang
- Institute of Hypertension of the People′s Hospital of Xinjiang Uyger Autonomous Region, Center of Diagnosis, Treatment and Research of Hypertension, Xinjiang, 91, Tianchi Road, Urumqi, Xinjiang, China
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Kelly KR, Williamson DL, Fealy CE, Kriz DA, Krishnan RK, Huang H, Ahn J, Loomis JL, Kirwan JP. Acute altitude-induced hypoxia suppresses plasma glucose and leptin in healthy humans. Metabolism 2010; 59:200-5. [PMID: 19765784 PMCID: PMC2813366 DOI: 10.1016/j.metabol.2009.07.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 07/10/2009] [Accepted: 07/15/2009] [Indexed: 01/03/2023]
Abstract
To examine the effects of acute altitude-induced hypoxia on the hormonal and metabolic response to ingested glucose, 8 young, healthy subjects (5 men and 3 women; age, 26 +/- 2 years; body mass index, 23.1 +/- 1.0 kg/m(2)) performed 2 randomized trials in a hypobaric chamber where a 75-g glucose solution was ingested under simulated altitude (ALT, 4300 m) or ambient (AMB, 362 m) conditions. Plasma glucose, insulin, C-peptide, epinephrine, leptin, and lactate concentrations were measured at baseline and 30, 60, 90, and 120 minutes after glucose ingestion during both trials. Compared with AMB, the plasma glucose response to glucose ingestion was reduced during the ALT trial (P = .04). There were no differences in the insulin and C-peptide responses between trials or in insulin sensitivity based on the homeostasis model assessment of insulin resistance. Epinephrine and lactate were both elevated during the ALT trial (P < .05), whereas the plasma leptin response was reduced compared with AMB (P < .05). The data suggest that the plasma glucose response is suppressed at ALT, but this is not due to insulin per se because insulin and C-peptide levels were similar for both trials. Elevated plasma epinephrine and lactate during ALT are indicative of increased glycogenolysis, which may have masked the magnitude of the reduced glucose response. We conclude that, during acute altitude exposure, there is a rapid metabolic response that is accompanied by a shift in the hormonal milieu that appears to favor increased glucose utilization.
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Affiliation(s)
- Karen R. Kelly
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH 44109
| | - David L. Williamson
- Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV 26506
| | - Ciarán E. Fealy
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - David A. Kriz
- Noll Physiological Research Center, Pennsylvania State University, University Park, PA 16802
| | - Raj K. Krishnan
- Noll Physiological Research Center, Pennsylvania State University, University Park, PA 16802
| | - Hazel Huang
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Janice Ahn
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH 44109
| | - Joseph L. Loomis
- Noll Physiological Research Center, Pennsylvania State University, University Park, PA 16802
| | - John P. Kirwan
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH 44109
- Department of Gastroenterology/Hepatology, Cleveland Clinic, Cleveland, OH 44195
- Department of Physiology, Case Western Reserve University School of Medicine, Cleveland, OH 44109
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Ikemoto T, Hosoya T, Takata K, Aoyama H, Hiramatsu T, Onoe H, Suzuki M, Endo M. Functional role of neuroendocrine-specific protein-like 1 in membrane translocation of GLUT4. Diabetes 2009; 58:2802-12. [PMID: 19720795 PMCID: PMC2780876 DOI: 10.2337/db09-0756] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE In skeletal muscles, dantrolene inhibits the exercise-induced membrane translocation of GLUT4. It has been postulated that the inhibitory action of dantrolene on Ca(2+) release from the sarcoplasmic reticulum (SR) causes inhibition of exercise-induced glucose uptake; however, the precise mechanism has not been adequately studied. RESEARCH DESIGN AND METHODS We discovered that dantrolene can bind to skeletal-type neuroendocrine-specific protein-like 1 (sk-NSPl1) with photoreactive dantrolene derivatives. In sk-NSPl1-deficient muscles, we examined the change in glucose uptake and the membrane translocation of GLUT4. In addition, we examined the change in blood glucose and also measured the glycogen level in both isolated and in situ skeletal muscles after electrical stimulation using our mutant mouse. RESULTS In sk-NSPl1-deficient muscles, exercise-induced glucose uptake was totally abolished with no change in insulin-induced glucose uptake. The Ca(2+) release mechanism and its inhibition by dantrolene were completely preserved in these muscles. The expression of GLUT4 in the mutant muscles also appeared unchanged. Confocal imaging and results using the membrane isolation method showed that exercise/contraction did not enhance GLUT4 translocation in these sk-NSPl1-deficient muscles under conditions of adequate muscle glycogen consumption. The blood glucose level in normal mice was reduced by electrical stimulation of the hind limbs, but that in mutant mice was unchanged. CONCLUSIONS sk-NSPl1 is a novel dantrolene receptor that plays an important role in membrane translocation of GLUT4 induced by contraction/exercise. The 23-kDa sk-NSPl1 may also be involved in the regulation of glucose levels in the whole body.
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Affiliation(s)
- Takaaki Ikemoto
- Functional Probe Research Laboratory, RIKEN Center for Molecular Imaging Science, Kobe, Japan.
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Blair DR, Funai K, Schweitzer GG, Cartee GD. A myosin II ATPase inhibitor reduces force production, glucose transport, and phosphorylation of AMPK and TBC1D1 in electrically stimulated rat skeletal muscle. Am J Physiol Endocrinol Metab 2009; 296:E993-E1002. [PMID: 19190254 PMCID: PMC2681314 DOI: 10.1152/ajpendo.91003.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Contraction-stimulated glucose transport by skeletal muscle appears to be caused by the cumulative effects of multiple inputs [potentially including AMP-activated protein kinase (AMPK), Ca(2+) flux, and force production], making it challenging to isolate the roles of these putative regulatory factors. To distinguish the effects of force production from the direct consequences of Ca(2+) flux, the predominantly type II rat epitrochlearis muscle was incubated without (vehicle) or with N-benzyl-p-toluenesulfonamide (BTS), a highly specific myosin II ATPase inhibitor that prevents force production by electrically stimulated (ES) type II fibers without altering cytosolic Ca(2+). In ES muscles, BTS vs. vehicle had an 84% reduction in force production and a 57% decrement in contraction-stimulated 3-O-methylglucose transport (3MGT). BTS did not alter the ES increase in phosphorylation of CaMKII (indicative of cytosolic Ca(2+)) or the amount of glycogen depletion. ES caused significant reductions in ATP (48%) and phosphocreatine (67%) concentrations for vehicle-treated muscles. For BTS-treated muscles, ES did not reduce ATP and caused only a 42% decrease in phosphocreatine. There was an ES increase in phosphorylation of AMPK, acetyl-CoA carboxylase (an AMPK substrate), and TBC1D1 for vehicle-treated muscles but not for BTS-treated muscles. These results point toward an essential role for tension-related events, including AMPK activation, in the 57% contraction-stimulated increase in 3MGT that was inhibited by BTS and further suggest a possible role for TBC1D1 phosphorylation. Non-tension-related events (e.g., increased cytosolic Ca(2+) rather than increased AMPK and TBC1D1 phosphorylation) are implicated in the contraction-stimulated increase in 3MGT that persisted in the presence of BTS.
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Affiliation(s)
- David R Blair
- University of Michigan, Division of Kinesiology, Ann Arbor, MI 48109-2214, USA
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Ramachandra Rao SP, Wassell R, Shaw MA, Sharma K. Profiling of human mesangial cell subproteomes reveals a role for calmodulin in glucose uptake. Am J Physiol Renal Physiol 2007; 292:F1182-9. [PMID: 17200159 DOI: 10.1152/ajprenal.00268.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proteomics combined with cell fractionation was used to identify proteins regulated by high glucose (HG) in human mesangial cells (HMC). Total membrane and cytosolic fraction proteins derived from HMC after 7 days of HG exposure were resolved by a two-dimensional gel electrophoresis approach. DeCyder software was used to analyze the HG-induced protein spot dysregulation. In the membrane subproteome, of the 92 spots that were matched across all gels, HG induced significant downregulation of only 4 protein spots. The dysregulated spots from the membrane subproteome included binding protein (BiP), calreticulin precursor protein, a 63-kDa transmembrane protein from a ER/Golgi intermediate, and beta-subunit of collagen proline 4-hydroxylase. In the cytosolic subproteome, of the 122 spots that were matched across all gels, HG induced downregulation of 3 protein spots and upregulation of 2 protein spots significantly. Enolase 1, annexin VI, and gamma(2)-actin were decreased, whereas heat shock protein-70 kDa and calmodulin (CaM) were increased. Further confocal microscopy and Western immunoblotting of mesangial cells validated the increase in CaM. Immunoblotting of diabetic mouse and rat kidneys exhibited a marked increase in CaM at both early and late stages of diabetes, reflecting the potential physiological relevance of CaM upregulation. CaM-specific inhibitors blocked glucose transport stimulated by transforming growth factor-beta and insulin in mesangial cells. In conclusion, using a combination of cell fractionation and protein expression profiling, we identified a cohort of HG-dysregulated proteins in the HMC and identified a critical and as yet unrecognized role for CaM in glucose transport in mesangial cells.
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Affiliation(s)
- Satish P Ramachandra Rao
- Dept. of Medicine, Center for Novel Therapies for Kidney Disease, Suite 365 Jefferson Alumni Hall, 1020 Locust St., Philadelphia, PA 19107, USA.
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Nolte LA, Han DH, Hansen PA, Hucker KA, Holloszy JO. A peroxovanadium compound stimulates muscle glucose transport as powerfully as insulin and contractions combined. Diabetes 2003; 52:1918-25. [PMID: 12882906 DOI: 10.2337/diabetes.52.8.1918] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Stimulation of glucose transport by insulin involves tyrosine phosphorylation of the insulin receptor (IR) and IR substrates (IRSs). Peroxovanadates inhibit tyrosine phosphatases, also resulting in tyrosine phosphorylation of the IRSs. Muscle contractions stimulate glucose transport by a mechanism independent of the insulin-signaling pathway. We found that the peroxovanadate compound bis-peroxovanadium,1,10-phenanthrolene [bpV(phen)] stimulates glucose transport to the same extent as the additive effects of maximal insulin and contraction stimuli. Translocation of GLUT4 to the cell surface mediates stimulation of glucose transport. There is evidence suggesting there are separate insulin- and contraction-stimulated pools of GLUT4-containing vesicles. We tested the hypothesis that bpV(phen) stimulates both the insulin- and the contraction-activated pathways. Stimulation of glucose transport and GLUT4 translocation by bpV(phen) was completely blocked by the phosphatidylinositol 3-kinase (PI 3-K) inhibitors wortmannin and LY294002. The combined effect of bpV(phen) and contractions was no greater than that of bpV(phen) alone. Activation of the IRS-PI 3-K signaling pathway was much greater with bpV(phen) than with insulin. Our results suggest that the GLUT4 vesicles that are normally translocated in response to contractions but not insulin can respond to the signal generated via the IRS-PI 3-K pathway if it is sufficiently powerful.
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Affiliation(s)
- Lorraine A Nolte
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Terada S, Muraoka I, Tabata I. Changes in [Ca2+]i induced by several glucose transport-enhancing stimuli in rat epitrochlearis muscle. J Appl Physiol (1985) 2003; 94:1813-20. [PMID: 12547839 DOI: 10.1152/japplphysiol.00780.2002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The purpose of the present investigation was to establish a method for estimating intracellular Ca(2+) concentrations ([Ca(2+)](i)) in isolated rat epitrochlearis muscles. Epitrochlearis muscles excised from 4-wk-old male Sprague-Dawley rats were loaded with a fluorescent Ca(2+) indicator, fura 2-AM, for 60-90 min at 35 degrees C in oxygenated Krebs-Henseleit buffer. After fura 2 loading and subsequent 20-min incubation, the intensities of 500-nm fluorescence, induced by 340- and 380-nm excitation lights (F(total)340 and F(total)380), were measured. The fluorescences specific to fura-2 (F(fura 2)340 and F(fura 2)380) were calculated by subtracting the non-fura 2-specific component from F(total)340 and F(total)380, respectively. The ratio of F(fura 2)340 to F(fura 2)380 was calculated as R, and the change in the ratio from the baseline value (DeltaR) was used as an index of the change in [Ca(2+)](i). In resting muscle, DeltaR was stable for 60 min. Incubation for 20 min with caffeine (3-10 mM) significantly increased DeltaR in a concentration-dependent manner. Incubation with hypoxic Krebs-Henseleit buffer for 10-60 min significantly elevated DeltaR, depending on the duration of the incubation. Incubation with 50 microM N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide for 20 min significantly elevated DeltaR (P < 0.05). No significant increases in DeltaR were observed during incubation for 20 min with 2 mM 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside or with 2 mU/ml insulin. These results demonstrated that, by using the fura 2-AM fluorescence method, the changes in [Ca(2+)](i) can be monitored in the rat epitrochlearis muscle and suggest that the method can be utilized to observe quantitative information regarding [Ca(2+)](i) that may be involved in contraction- and hypoxia-stimulated glucose transport activity in skeletal muscle.
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Affiliation(s)
- Shin Terada
- Laboratory of Exercise Physiology, Div. of Health Promotion and Exercise, National Inst. of Health & Nutrition, 1-23-1 Toyama, Shinjuku City, Tokyo 162-8636, Japan
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Abstract
This historical review describes the research on the regulation of glucose transport in skeletal muscle conducted in my laboratory and in collaboration with a number of colleagues in other laboratories. This research includes studies of stimulation of glucose transport, GLUT4 translocation, and GLUT4 expression by exercise/muscle contractions, the role of Ca(2+) in these processes, and the interactions between the effects of exercise and insulin. Among the last are the additive effects of insulin and contractions on glucose transport and GLUT4 translocation and the increases in muscle insulin sensitivity and responsiveness induced by exercise.
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Affiliation(s)
- John O Holloszy
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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12
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Abstract
Glucose transport, the rate limiting step in glucose metabolism in skeletal muscle, is mediated by insulin-sensitive glucose transporter 4 (GLUT4) and can be activated in skeletal muscle by two separate and distinct signalling pathways: one stimulated by insulin and the second by muscle contractions. Skeletal muscle is the principal tissue responsible for insulin-stimulated glucose disposal and thus the major site of peripheral insulin resistance. Impaired glucose transport in skeletal muscle leads to impaired whole body glucose uptake, and contributes to the pathogenesis of Type 2 diabetes mellitus. A combination of genetic and environmental factors is likely to contribute to the pathogenesis of Type 2 diabetes mellitus; however, the primary defect is still unknown. Intense efforts are underway to define the molecular mechanisms that regulate glucose metabolism in insulin sensitive tissues. This review will present our current understanding of mechanisms regulating glucose transport in skeletal muscle in humans. Elucidation of the pathways involved in the regulation of glucose homeostasis will offer insight into the pathogenesis of insulin resistance and Type 2 diabetes mellitus and may lead to the identification of biochemical entry points for drug intervention to improve glucose homeostasis.
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Affiliation(s)
- H A Koistinen
- Department of Clinical Physiology, Karolinska Hospital, Karolinska Institutet, Stockholm, Sweden
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13
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Clanton TL, Klawitter PF. Invited review: Adaptive responses of skeletal muscle to intermittent hypoxia: the known and the unknown. J Appl Physiol (1985) 2001; 90:2476-87. [PMID: 11356816 DOI: 10.1152/jappl.2001.90.6.2476] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intermittent hypoxia (IH) describes conditions of repeated, transient reductions in O2 that may trigger unique adaptations. Rest periods during IH may avoid potentially detrimental effects of long-term O2 deprivation. For skeletal muscle, IH can occur in conditions of obstructive sleep apnea, transient altitude exposures (with or without exercise), intermittent claudication, cardiopulmonary resuscitation, neonatal blood flow obstruction, and diving responses of marine animals. Although it is likely that adaptations in these conditions vary, some patterns emerge. Low levels of hypoxia shift metabolic enzyme activity toward greater aerobic poise; extreme hypoxia shifts metabolism toward greater anaerobic potential. Some conditions of IH may also inhibit lactate release during exercise. Many related cellular phenomena could be involved in the response, including activation of specific O2 sensors, reactive oxygen and nitrogen species, preconditioning, hypoxia-induced transcription factors, regulation of ion channels, and influences of paracrine/hormonal stimuli. The net effect of a variety of adaptive programs to IH may be to preserve contractile function and cell integrity in hypoxia or anoxia, a response that does not always translate into improvements in exercise performance.
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Affiliation(s)
- T L Clanton
- Department of Internal Medicine (Pulmonary and Critical Care Division), Dorothy Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA.
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Yu M, Blomstrand E, Chibalin AV, Wallberg-Henriksson H, Zierath JR, Krook A. Exercise-associated differences in an array of proteins involved in signal transduction and glucose transport. J Appl Physiol (1985) 2001; 90:29-34. [PMID: 11133890 DOI: 10.1152/jappl.2001.90.1.29] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vastus lateralis muscle biopsies were obtained from endurance-trained (running approximately 50 km/wk) and untrained (no regular physical exercise) men, and the expression of an array of insulin-signaling intermediates was determined. Expression of insulin receptor and insulin receptor substrate-1 and -2 was decreased 44% (P < 0.05), 57% (P < 0.001), and 77% (P < 0.001), respectively, in trained vs. untrained muscle. The downstream signaling target, Akt kinase, was not altered in trained subjects. Components of the mitogenic signaling cascade were also assessed. Extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase expression was 190% greater (P < 0.05), whereas p38 mitogen-activated protein kinase expression was 32% lower (P < 0.05), in trained vs. untrained muscle. GLUT-4 protein expression was twofold higher (P < 0.05), and the GLUT-4 vesicle-associated protein, the insulin-regulated aminopeptidase, was increased 4.7-fold (P < 0. 05) in trained muscle. In conclusion, the expression of proteins involved in signal transduction is altered in skeletal muscle from well-trained athletes. Downregulation of early components of the insulin-signaling cascade may occur in response to increased insulin sensitivity associated with endurance training.
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Affiliation(s)
- M Yu
- Department of Clinical Physiology, Karolinska Hospital, SE-171 76 Stockholm, Sweden
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Bruton JD, Katz A, Westerblad H. Insulin increases near-membrane but not global Ca2+ in isolated skeletal muscle. Proc Natl Acad Sci U S A 1999; 96:3281-6. [PMID: 10077675 PMCID: PMC15933 DOI: 10.1073/pnas.96.6.3281] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has long been debated whether changes in Ca2+ are involved in insulin-stimulated glucose uptake in skeletal muscle. We have now investigated the effect of insulin on the global free myoplasmic Ca2+ concentration and the near-membrane free Ca2+ concentration ([Ca2+]mem) in intact, single skeletal muscle fibers from mice by using fluorescent Ca2+ indicators. Insulin has no effect on the global free myoplasmic Ca2+ concentration. However, insulin increases [Ca2+]mem by approximately 70% and the half-maximal increase in [Ca2+]mem occurs at an insulin concentration of 110 microunits per ml. The increase in [Ca2+]mem by insulin persists when sarcoplasmic reticulum Ca2+ release is inhibited but is lost by perfusing the fiber with a low Ca2+ medium or by addition of L-type Ca2+ channel inhibitors. Thus, insulin appears to stimulate Ca2+ entry into muscle cells via L-type Ca2+ channels. Wortmannin, which inhibits insulin-mediated activation of glucose transport in isolated skeletal muscle, also inhibits the insulin-mediated increase in [Ca2+]mem. These data demonstrate a new facet of insulin signaling and indicate that insulin-mediated increases in [Ca2+]mem in skeletal muscle may underlie important actions of the hormone.
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Affiliation(s)
- J D Bruton
- Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden
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Derave W, Hespel P. Role of adenosine in regulating glucose uptake during contractions and hypoxia in rat skeletal muscle. J Physiol 1999; 515 ( Pt 1):255-63. [PMID: 9925895 PMCID: PMC2269136 DOI: 10.1111/j.1469-7793.1999.255ad.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. The effect of A1-adenosine receptor antagonism via 8-cyclopentyl-1,3-dipropyl-xanthine (CPDPX) on the stimulation of skeletal muscle glucose uptake by contractions and hypoxia was investigated in isolated perfused rat hindquarters. The standard perfusate contained either no insulin or a submaximal insulin concentration at 100 microU ml-1. 2. Muscles were stimulated to contract for 45 min by intermittent tetanic stimulation of the sciatic nerve. Hypoxia was induced by reducing perfusate haematocrit from 30% to 10% on the one hand, and by switching the gassing of the perfusate from a 35% to a 0% O2 mixture for 60 min on the other hand. The effect of contractions and hypoxia alone, or in combination, was investigated. 3. Hypoxia-induced muscle glucose uptake was not altered by CPDPX in the absence or presence of insulin. In contrast, contraction-induced glucose uptake was reduced by approximately 25 % (P < 0.05) by exposure of muscles to CPDPX. CPDPX did not affect hindlimb glucose uptake either before or after contractions. 4. The increment of muscle glucose uptake during hypoxia combined with contractions was greater (P < 0.05) than the effect of hypoxia alone. 5. The current findings provide evidence that the mechanism by which hypoxia stimulates muscle glucose uptake is, at least in part, different from the mechanism of glucose uptake stimulation by contractions, because (i) A1-adenosine receptors regulate insulin-mediated glucose uptake in muscle during contractions but not during hypoxia and (ii) submaximal hypoxia and contractions are additive stimuli to muscle glucose uptake.
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Affiliation(s)
- W Derave
- Institute for Kinesiology and Sport Sciences, Universiteit Gent, B-9000 Gent, Belgium
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