Diabetes
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Iossa, S.
Right arrow Articles by Liverini, G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Iossa, S.
Right arrow Articles by Liverini, G.
Social Bookmarking
Add to CiteULike   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

Diabetes 53:2861-2866, 2004
© 2004 by the American Diabetes Association, Inc.

A Possible Link Between Skeletal Muscle Mitochondrial Efficiency and Age-Induced Insulin Resistance

Susanna Iossa, Maria Pina Mollica, Lillà Lionetti, Raffaella Crescenzo, Rosaria Tasso, and Giovanna Liverini

From the Department of General and Environmental Physiology, University of Naples "Federico II," Naples, Italy


   ABSTRACT
TOP
 ABSTRACT
RESEARCH DESIGN AND METHODS
 RESULTS
 DISCUSSION
 References
 
The transition from young to adult age is associated with decreased insulin sensitivity. To investigate whether changes in skeletal muscle mitochondrial function could be involved in the development of insulin resistance, we measured the oxidative capacity and energetic efficiency of subsarcolemmal and intermyofibrillar mitochondria isolated from the skeletal muscle of 60- and 180-day-old rats. Mitochondrial efficiency was tested by measuring the degree of thermodynamic coupling and optimal thermodynamic efficiency, as well as mitochondrial proton leak, which was determined in both the absence (basal) and the presence (fatty acid induced) of palmitate. Serum glucose, insulin, and HOMA index were also measured. The results show that in adult rats, concomitant with increased HOMA index, skeletal muscle mitochondria display higher respiratory capacity and energy efficiency. In fact, thermodynamic coupling and optimal thermodynamic efficiency significantly increased and fatty acid-induced proton leak was significantly lower in the skeletal muscle mitochondria from adult than in younger rats. A deleterious consequence of increased mitochondrial efficiency would be a reduced utilization of energy substrates, especially fatty acids, leading to intracellular triglyceride accumulation and lipotoxicity, thus contributing to the onset of skeletal muscle insulin resistance.

Increasing age is associated with obesity and insulin resistance not only in humans but also in rodents (1–5). In fact, ad libitum-fed caged rats are a good animal model that simulates the situation (sedentary lifestyle and unrestricted diet) of people in the western world.

It has been previously shown that age-induced insulin resistance in rats is already detectable at 4 months of age, concomitant to a rapid rise in fat mass, and does not further increase later in life (3). This early decrease in insulin sensitivity could in turn lead to the metabolic disturbance typical of old age.

Our previous results also indicate that in the transition from postpubertal (60 days) to adult (180 days) age, rats display reduced sensitivity to the anorexic effect of leptin (6) and, at the cellular level, hepatic mitochondrial machinery shows some age-related biochemical impairment (7,8). From all the above findings, it can be deduced that adult rats can be considered a good experimental tool for studying the onset of the "aging" phenomenon.

It has been postulated that defects in mitochondrial performance could contribute to the development of insulin resistance (9), and mitochondrial oxidative capacity has been considered a good predictor of insulin sensitivity (10). These suggestions are not surprising since control of mitochondrial respiration and oxidative phosphorylation is fundamental for the maintenance of cellular homeostasis. The above control is exerted at two levels, i.e., regulation of the rate of oxygen consumption and ATP production and regulation of oxidative phosphorylation efficiency (11). The main determinant of oxidative phosphorylation efficiency is represented by the degree of coupling between oxygen consumption and ATP synthesis, which is always lower than 1 and can vary according to the metabolic needs of the cell (12). Among the factors that affect mitochondrial degree of coupling, the permeability of the mitochondrial inner membrane to H+ ions (leak) plays an important role. It is now well known that the mitochondrial inner membrane exhibits a basal proton leak pathway whose contribution to basal metabolic rate in rats has been estimated to be ~20–25% (13). In addition, it is well known that fatty acids can act as natural uncouplers of oxidative phosphorylation by generating a fatty acid-dependent proton leak pathway (14–16), which is a function of the amount of unbound fatty acids in the cell.

Taking into account the above considerations, we considered it of interest to investigate mitochondrial performance and efficiency in 60- and 180-day-old rats. To this purpose, we measured basal and fatty acid-mediated proton leak and the parameters of thermodynamic coupling and efficiency in mitochondria isolated from skeletal muscle. In fact, skeletal muscle is the primary site of insulin action and is thus inherently linked to the development of whole-body insulin resistance (17). Analyses were carried out, taking into account that the skeletal muscle mitochondrial population is heterogeneous for localization, function, and regulation (18–21). In fact, mitochondria located beneath the sarcolemmal membrane (subsarcolemmal [SS]) exhibit lower respiratory rates than those located between the myofibrils (intermyofibrillar [IMF]), and aging has been shown to selectively affect IMF mitochondria in heart (22). A metabolic characterization of young and adult rats was obtained by measuring serum insulin, leptin, nonesterified fatty acid (NEFA), and glucose levels.


   RESEARCH DESIGN AND METHODS
TOP
 ABSTRACT
 RESEARCH DESIGN AND METHODS
RESULTS
 DISCUSSION
 References
 
Two groups of eight male Wistar rats (Charles River, Calco, Como, Italy) (aged 60 [young] and 180 [adult] days) were used for this study. They were kept at 24°C under an artificial circadian 12-h light/12-h dark cycle, with ad libitum access to water and a standard stock diet (Mucedola 4RF21; Settimo Milanese, Milan, Italy). Treatment, housing, and killing met the guidelines of the Italian Health Ministry.

On the day they were killed and without any previous food deprivation, the rats were anesthetized by an injection of chloral hydrate (40 mg/100 g body wt i.p.) and blood was collected from the inferior cava vein. Immediately after blood collection, hind leg muscles were rapidly removed and used for the preparation of SS and IMF mitochondria (18), while the rat carcasses were used for determination of body composition (18).

Measurements of mitochondrial respiration parameters, thermodynamic coupling, and efficiency.
Oxygen consumption was measured polarographically with a Clark-type electrode (Yellow Springs Instruments, Yellow Springs, OH) at 30°C in a medium containing 30 mmol/l KCl, 6 mmol/l MgCl2, 75 mmol/l sucrose, 1 mmol/l EDTA, 20 mmol/l KH2PO4, pH 7.0, and 0.1% (wt/vol) fatty acid-free BSA. Substrates used were 10 mmol/l succinate plus 3.75 µmol/l rotenone, 10 mmol/l glutamate plus 2.5 mmol/l malate, or 40 µmol/l palmitoylCoA plus 2 mmol/l carnitine plus 2.5 mmol/l malate. Measurements were performed in the absence (state 4) and presence (state 3) of 0.6 mmol/l ADP. Respiratory control ratio (RCR) was calculated as the ratio between states 3 and 4.

The degree of thermodynamic coupling (q) was obtained by applying equation 11 by Cairns et al. (23).

where Jo represents oxygen consumption. (Jo)sh and (Jo)unc were measured as above using succinate plus rotenone in the presence of 2 µg/ml oligomycin or 1 µmol/l FCCP [carbonyl cyanide 4-(trifluoro-methoxy)phenylhydrazone], respectively. The optimal thermodynamic efficiency of oxidative phosphorylation was calculated by using equation 13 by Cairns et al. (23).

The adenine nucleotide translocase (ANT) content of SS and IMF mitochondria was determined by titrating state 3 respiration with increasing concentrations of carboxyatractyloside (24) in a medium containing 30 mmol/l KCl, 6 mmol/l MgCl2, 75 mmol/l sucrose, 1 mmol/l EDTA, 20 mmol/l KH2PO4, 0.1% (wt/vol) fatty acid-free BSA, 10 mmol/l succinate, and 3.75 µmol/l rotenone (pH 7.0). Cytochrome oxidase (COX) specific activity was measured polarographically with a Clark-type electrode (Yellow Springs Instruments) at 30°C in a medium containing 30 µmol/l cytochrome c, 4 µmol/l rotenone, 0.5 mmol/l dinitrophenol, 10 mmol/l Na-malonate, and 75 mmol/l Hepes (pH 7.4) (25).

Measurements of basal proton leak kinetics.
Oxygen consumption was measured polarographically with a Clark-type electrode (Yellow Springs Instruments) maintained at 30°C in a medium containing 30 mmol/l LiCl, 6 mmol/l MgCl2, 75 mmol/l sucrose, 1 mmol/l EDTA, 20 mmol/l Tris-PO4, pH 7.0, and 0.1% (wt/vol) fatty acid-free BSA. Titration of state 4 respiration was carried out by sequential additions of up to 5 mmol/l malonate in the presence of 10 mmol/l succinate, 3.75 µmol/l rotenone, 2 µg/ml oligomycin, 83.3 nmol/mg safranin O, and 80 ng/ml nigericin. Mitochondrial membrane potential recordings were performed in parallel with safranin O using a JASCO dual-wavelength spectrophotometer (511–533 nm) (26). The absorbance readings were transformed into mV membrane potential using the Nernst equation: {Delta}{psi} = 61 mV x log ([K+]in/[K+]out). Calibration curves made for each preparation were obtained from traces in which the extramitochondrial K+ level ([K+]out) was altered in the 0.1- to 20-mmol/l range. The change in absorbance caused by the addition of 3 µmol/l valinomycin was plotted against [K+]out. Then, [K+]in was estimated by extrapolation of the line to the zero uptake point.

Measurement of palmitate-induced proton leak kinetics.
Mitochondrial membrane potential and oxygen consumption were measured as above in the presence of 10 mmol/l succinate, 3.75 µmol/l rotenone, 2 µg/ml oligomycin, 83.3 nmol/mg safranin O, and palmitate at a concentration of 45 µmol/l for SS mitochondria or 75 µmol/l for IMF mitochondria. Due to the presence of 0.1% BSA in the incubation medium, the above concentrations of palmitate correspond to 17 (for SS mitochondria) and 62 (for IMF mitochondria) nmol/l free (not bound) fatty acid calculated using the equation of Richieri et al. (27). Palmitate-induced proton leak was estimated from titration of respiration by sequential additions of up to 600 µmol/l malonate for IMF and 1 mmol/l for SS mitochondria.

Measurement of uncoupling protein 3 (UCP3) protein content.
Mitochondrial protein content of UCP3 was estimated by Western blot analysis, as previously reported (28), by using UCP3 polyclonal antibodies (Chemicon).

Circulating substrate and hormone serum concentrations.
Serum insulin and leptin concentrations were measured using radioimmunoassay kits in a single assay to remove interassay variations (Linco Research, St. Charles, MO). Serum glucose and NEFA concentrations were measured by colorimetric enzymatic method using commercial kits (Pokler Italia, Genova, Italy, and Roche Diagnostics, Mannheim, Germany, respectively). Insulin resistance was assessed by homeostasis model assessment (HOMA) index ([glucose {mg/dl} x insulin {mU/l}]/405) (29).

Statistical analysis.
Data are summarized using means ± SE for eight rats. Statistical analyses were performed using a two-tailed unpaired Student’s t test or nonlinear regression curve fit. All analyses were performed using GraphPad Prism (version 4; GraphPad Software, San Diego, CA).

ADP, succinate, rotenone, glutamate, malate, carnitine, palmitoylCoA, ascorbate, dinitrophenol, TMPD (N, N, N', N'-tetramethyl-p-phenylenediamine), nigericin, nagarse, oligomycin, and safranin O were purchased from Sigma Chemical (St. Louis, MO). Carboxyatractyloside was purchased from Calbiochem (San Diego, CA). All other reagents were of the highest purity commercially available.


   RESULTS
TOP
 ABSTRACT
 RESEARCH DESIGN AND METHODS
 RESULTS
DISCUSSION
 References
 
The transition from young (60 days) to adult (180 days) age in Wistar rats was associated with a significant increase in body weight and body lipids (Table 1). In addition, significantly higher serum concentrations of leptin, insulin, and NEFAs, together with higher HOMA index, were found in 180-day-old compared with younger rats (Table 1).


View this table:
[in this window]
[in a new window]
  		TABLE 1 Body composition and serum levels of substrates and hormones in 60- and 180-day-old rats

 
Skeletal muscle mitochondrial oxidative capacity was evaluated using lipid and FAD- and NAD-linked substrates. The results obtained in SS mitochondria (Table 2) show that state 3 respiratory rates and RCR values significantly increased in 180- compared with 60-day-old rats, irrespective of the substrate used. No variation in state 4 respiratory rates with any substrate, ANT content, and COX specific activity (Table 2) due to age was found, while UCP3 protein content significantly increased in 180- compared with 60-day-old rats. As for IMF mitochondria (Table 3), a significant increase in state 3 respiratory rates was only found in 180- compared with 60-day-old rats with glutamate, a NAD-linked substrate, although the values with FAD-linked and lipid substrate tended to be higher. State 4 respiratory rates tended to be lower with all the substrates used in 180-day-old rats, although statistical significance was never reached. Consequently, a significant increase in RCR values was found in 180-day-old rats with all the substrates. In addition, ANT content significantly decreased, UCP3 protein content significantly increased, and no significant variation was found in COX specific activity in 180-day-old rats (Table 3).


View this table:
[in this window]
[in a new window]
  		TABLE 2 Respiratory capacities in SS skeletal muscle mitochondria from 60- and 180-day-old rats

 

View this table:
[in this window]
[in a new window]
  		TABLE 3 Respiratory capacities in IMF skeletal muscle mitochondria from 60- and 180-day-old rats

 
The degree of thermodynamic coupling (q) and optimal thermodynamic efficiency ({eta}) were calculated to allow evaluation of energetic efficiency of the mitochondrial populations from skeletal muscle. The results show that both SS and IMF mitochondria from 180-day-old rats exhibited higher q and {eta} values compared with mitochondria from 60-day-old rats (Table 4).


View this table:
[in this window]
[in a new window]
  		TABLE 4 Calculated thermodynamic coupling values (q) and optimal thermodynamic efficiency ({eta}) of oxidative phosphorylation in SS and IMF skeletal muscle mitochondria from 60- and 180-day-old rats

 
Figures 1 and 2 illustrate titration of steady-state respiration rate as a function of mitochondrial membrane potential in SS and IMF skeletal muscle mitochondria. The above titration curves are an indirect measurement of proton leak, since steady-state oxygen consumption rate (i.e., proton efflux rate) in nonphosphorylating mitochondria is equivalent to the proton influx rate due to proton leak. The results show that no variation in basal proton leak was found in SS and IMF mitochondria from 180- compared with 60-day-old rats (Fig. 1). On the other hand, fatty acid-induced proton leak (Fig. 2) significantly decreased in SS and IMF mitochondria in 180- compared with 60-day-old rats.



View larger version (24K):
[in this window]
[in a new window]
  		FIG. 1. Kinetics of basal proton leak in SS (A) and IMF (B) skeletal muscle mitochondria from 60- and 180-day-old rats. Results are reported as means ± SE of eight different rats. Basal proton leak was not significantly different in 180- compared with 60-day-old rats, as shown by nonlinear regression curve fits.

 


View larger version (25K):
[in this window]
[in a new window]
  		FIG. 2. Kinetics of palmitate-induced proton leak in SS (A) and IMF (B) skeletal muscle mitochondria from 60- and 180-day-old rats. Results are reported as means ± SE of eight different rats. Palmitate-induced proton leak was significantly (P < 0.05) lower in 180- compared with 60-day-old rats, as shown by nonlinear regression curve fits.

 

   DISCUSSION
TOP
 ABSTRACT
 RESEARCH DESIGN AND METHODS
 RESULTS
 DISCUSSION
References
 
This study reveals that, in adult rats, higher HOMA index is associated with an increase in oxidative capacity and energy efficiency in skeletal muscle mitochondria. Adult rats can be considered a good experimental tool for studying the onset of the aging phenomenon. In fact, we have found that at 180 days of age, rats display signs of age-induced metabolic disturbance, since they exhibit higher body weight and lipid mass, hyperinsulinemia, hyperleptinemia, and a higher HOMA index. These metabolic perturbations are in agreement with those previously found by others. In fact, Barzilai and Rossetti (3) found that an early fall in insulin responsiveness occurs in rats between 2 and 4 months of age. Our present results also show that, in adult rats, concomitantly with the above metabolic perturbations, there is an increase in skeletal muscle mitochondrial capacity and efficiency.

The generalized increase in state 3 oxidative capacity found in SS mitochondria from 180-day-old rats suggests an increase in one of the steps below complex II. The most feasible target of the above increase should be at the level of cytochromes and/or ATP synthetase, since COX activity was not significantly altered with increasing age, although a tendency to increase was detected. On the other hand, only a stimulation of complex I activity was evident in IMF mitochondria. The determination of ANT content in the two mitochondrial populations allows us to exclude that the above increase in respiratory rates is due to ANT, which was found unchanged or decreased in SS and IMF mitochondria, respectively. The divergent effect of increasing age on respiratory rates and ANT content is not contradictory, since ANT exerts a low control on mitochondrial respiration in skeletal muscle (30). A possible explanation for the different effect of increasing age on SS and IMF mitochondria could be that these two mitochondrial populations have different cellular localization and subserve different metabolic roles in the cell. In fact, IMF mitochondria mainly meet ATP requirements of the contractile elements, while SS mitochondria supply ATP for cytoplasmic reactions.

Previous results have shown that old rats display a decrease in skeletal muscle mitochondrial activities (31–33), and when SS and IMF mitochondria have been studied separately in the heart, the above decrease was found to be restricted to IMF organelles (22). In addition, we have previously found that an aging-induced decline in hepatic mitochondrial activity of complex II is already evident in 180-day-old rats (7), indicating that the liver is affected early by the aging process. Our present results show that skeletal muscle behaves very differently from liver and that, at 180 days of age, oxidative capacity has not yet reached its maximum. In agreement, it has been found that complex II-IV activity of skeletal muscle mitochondria peaks in middle life (1 year) and then declines with increasing age (32).

As for mitochondrial efficiency, both mitochondrial populations display an increase in the degree of thermodynamic coupling and optimal thermodynamic efficiency as well as a decreased fatty acid-dependent proton leak. For IMF mitochondria, decreased fatty acid-dependent proton leak is in agreement with the decreased ANT content of this mitochondrial population, while in SS mitochondria, the reduced sensitivity to palmitate is probably due to the other carrier systems involved, since their ANT content was not affected. Our results also underline the dissociation between regulation of mitochondrial fatty acid-dependent proton leak and UCP3 levels. In fact, the increased UCP3 protein content of SS and IMF mitochondria from 180-day-old rats is in contrast with the lower fatty acid-dependent leak but is consistent with the increased serum NEFA levels, which have been shown to be closely linked to changes in UCP3 protein expression (34).

A number of recent human studies have focused the attention on the mitochondrial compartment as a cellular site involved in the pathogenesis of insulin resistance. In fact, mitochondrial dysfunction has been found in old men (9) and insulin-resistant young subjects (35). In addition, a significant direct relationship between skeletal muscle oxidative capacity and insulin sensitivity has been found (10). An alternative way to reduce mitochondrial oxidation of energy substrates is to increase the efficiency of oxidative phosphorylation. In fact, a higher efficiency implies that less substrate needs to be burned to obtain ATP. Since NEFA serum levels are significantly higher in adult rats, a deleterious consequence of reduced substrate burning could be intracellular triglyceride accumulation and lipotoxicity. The above consequence is of relevance because one of the main causes leading to insulin resistance in skeletal muscle is intramuscular triglygeride deposition (17,36). In addition, skeletal muscle is the primary site of insulin action and is thus inherently linked to the development of whole-body insulin resistance (17).

The increased mitochondrial efficiency and resulting lower thermogenesis in 180-day-old rats could be due to a reduced sensitivity of skeletal muscle cell to leptin. In fact, it has been shown that leptin directly stimulates thermogenesis in skeletal muscle (37) and that 180-day-old rats display age-induced leptin resistance (6). Therefore, leptin resistance could be regarded as one of the primary events leading to insulin resistance.

In conclusion, our present results show that although at 180 days of age no clear biochemical impairment of mitochondrial machinery can be detected, an increased efficiency in the production of ATP takes place. The impact of this modification on cellular metabolism could contribute to the onset of skeletal muscle insulin resistance.


   ACKNOWLEDGMENTS
 
This work was supported by a grant from the Italian Ministry of Education, University and Research (COFIN 2002).

We thank Dr. Emilia De Santis for her skilful management of the animal house.

Address correspondence and reprint requests to Susanna Iossa, Dipartimento di Fisiologia Generale ed Ambientale, Via Mezzocannone 8, I-80134, Napoli, Italy. E-mail: susiossa{at}unina.it

Received for publication May 21, 2004 and accepted in revised form July 23, 2004

Abbreviations: ANT, adenine nucleotide translocase; COX, cytochrome oxidase; HOMA, homeostasis model assessment; IMF, intermyofibrillar; NEFA, nonesterified fatty acid; RCR, respiratory control ratio; SS, subsarcolemmal; UCP3, uncoupling protein 3


   References
TOP
 ABSTRACT
 RESEARCH DESIGN AND METHODS
 RESULTS
 DISCUSSION
 References
 

  1. Shimokata H, Tobin JD, Muller DC, Elahi D, Coon PJ, Andres R: Studies in the distribution of body fat. I. Effects of age, sex and obesity. J Gerontol44 :M66 –M73,1989[Medline]
  2. Reaven GM, Reaven EP: Age, glucose intolerance, and non-insulin dependent diabetes mellitus. J Am Geriatr Soc33 :286 –290,1985[Medline]
  3. Barzilai N, Rossetti L: Relationship between changes in body composition and insulin responsiveness in models of the aging rat. Am J Physiol269 :E591 –E597,1995
  4. Larkin LM, Reynolds TH, Supiano MA, Kahn BB, Halter JB: Effect of aging and obesity on insulin responsiveness and glut-4 glucose transporter content in skeletal muscle of Fisher 344 x Brown Norway rats. J Gerontol56 :B486 –B492,2001
  5. Iossa S, Mollica MP, Lionetti L, Crescenzo R, Botta M, Barletta A, Liverini G: Acetyl-L-carnitine supplementation differently influences nutrient partitioning, serum leptin concentration and skeletal muscle mitochondrial respiration in young and old rats. J Nutr132 :636 –642,2002[Abstract/Free Full Text]
  6. Iossa S, Lionetti L, Mollica MP, Barletta A, Liverini G: Energy intake and utilization vary during development in rats. J Nutr129 :1593 –1596,1999[Abstract/Free Full Text]
  7. Iossa S, Lionetti L, Mollica MP, Crescenzo R, Botta M, Liverini G: Mitochondrial respiration and triiodothyronine concentration in liver from postpubertal and adult rats. Horm Metab Res33 :343 –347,2001[Medline]
  8. Mollica MP, Iossa S, Liverini G, Soboll S: Oxygen consumption and byosynthetic function in perfused liver from rats at different stages of development. Cell Mol Life Sci54 :1277 –1282,1998[Medline]
  9. Petersen KF, Befroy D, Dufour S, Dziura J, Arijan C, Rothman DL, DiPietro L, Cline GW, Shulman GI: Mitochondrial disfunction in the elderly: possible role in insulin resistance. Science300 :1140 –1142,2003[Abstract/Free Full Text]
  10. Bruce CR, Anderson MJ, Carey AL, Newman DG, Bonen A, Kriketos AD, Cooney GJ, Hawley JA: Muscle oxidative capacity is a better predictor of insulin sensitivity than lipid status. J Clin Endocrinol Metab88 :5444 –5451,2003[Abstract/Free Full Text]
  11. Kadenbach B: Intrinsic and extrinsic uncoupling of oxidative phosphorylation. Biochim Biophys Acta1604 :77 –94,2003[Medline]
  12. Stucki JW: The optimal efficiency and the economic degrees of coupling of oxidative phosphorylation. Eur J Biochem109 :269 –283,1980[Medline]
  13. Rolfe DFS, Brown GC: Cellular energy utilisation and molecular origin of standard metabolic rate in mammals. Physiol Rev77 :731 –758,1997[Abstract/Free Full Text]
  14. Skulachev VP: Fatty acid circuit as a physiological mechanism of uncoupling of oxidative phosphorylation. FEBS Lett294 :158 –162,1991[Medline]
  15. Jezek P, Engstova H, Zackova M, Vercesi AE, Costa ADT, Arruda P, Garlid KD: Fatty acid cycling mechanism and mitochondrial uncoupling proteins. Biochim Biophys Acta1365 :319 –327,1998[Medline]
  16. Soboll S, Grundel S, Schwabe U, Scholtz R: Influence of fatty acids on energy metabolism. II. Kinetics of changes in metabolic rates and changes in subcellular adenine nucleotide contents and pH gradients following addition of octanoate and oleate in perfused rat liver. Eur J Biochem141 :231 –236,1984[Medline]
  17. Stannard SR, Johnson NA: Insulin resistance and elevated triglyceride in muscle: more important for survival than thrifty genes? J Physiol554 :595 –607,2003
  18. Iossa S, Mollica MP, Lionetti L, Crescenzo R, Botta M, Liverini G: Skeletal muscle oxidative capacity in rats fed high-fat diet. Int J Obes26 :65 –72,2002
  19. Bizeau ME, Willis WT, Hazel JR: Differential responses to endurance training in subsarcolemmal and intermyofibrillar mitochondria. J Appl Physiol85 :1279 –1284,1998[Abstract/Free Full Text]
  20. Cogswell AM, Stevens RJ, Hood DA: Properties of skeletal muscle mitochondria isolated from subsarcolemmal and intermyofibrillar regions. Am J Physiol264 :C383 –C389,1993
  21. Krieger DA, Tate CA, McMillin-Wood J, Booth FW: Populations of rat skeletal muscle mitochondria after exercise and immobilization. J Appl Physiol48 :23 –28,1980[Abstract/Free Full Text]
  22. Fannin SW, Lesnefsky EJ, Slabe TJ, Hassan MO, Hoppel CL: Aging selectively decreases oxidative capacity in rat heart interfibrillar mitochondria. Arch Biochem Biophys372 :399 –407,1999[Medline]
  23. Cairns CB, Walther J, Harken AH, Banerjee A: Mitochondrial oxidative phosphorylation efficiencies reflect physiological organ roles. Am J Physiol274 :R1376 –R1383,1998
  24. Vignais PV: Molecular and physiological aspects of adenine nucleotide transport in mitochondria. Biochim Biophys Acta456 :1 –38,1976[Medline]
  25. Barré H, Bailly L, Rouanet JL: Increased oxidative capacity in skeletal muscle from cold-acclimated ducklings: a comparison with rats. Comp Biochem Physiol88 :B5119 –B5522,1997
  26. Nedergard J: The relationship between extramitochondrial Ca2+ concentration, respiratory rate, and membrane potential in mitochondria from brown adipose tissue of the rat. Eur J Biochem133 :185 –191,1983[Medline]
  27. Richieri GV, Anel A, Kleinfeld AM: Interactions of long chain fatty acids and albumin: determination of free fatty acid levels using the fluorescent probe ADIFAB. Biochem32 :7574 –7580,1993[Medline]
  28. Iossa S, Mollica MP, Lionetti L, Crescenzo R, Botta M, Samec S, Solinas G, Mainieri D, Dulloo AG, Liverini: Skeletal muscle mitochondrial efficiency and uncoupling protein 3 in overeating rats with increased thermogenesis. Pflugers Arch445 :431 –436,2002 [Epub 6 November 2002][Medline]
  29. Matthews DR, Hosker JP, Rudenski AS, Naylor BA, Treacher DF, Turner RC: Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia28 :412 –419,1985[Medline]
  30. Rossignol R, Letellier T, Malgat M, Rocher C, Mazat JP: Tissue variation in the control of oxidative phosphorylation: implication for mitochondrial diseases. Biochem J347 :45 –53,2000
  31. Desai VG, Weindruck R, Hart RW, Feuers RJ: Influences of age and dietary restriction on gastrocnemius electron transport system activities in mice. Arch Biochem Biophys333 :145 –151,1996[Medline]
  32. Kwong LK, Sohal RS: Age-related changes in activities of mitochondrial electron transport complexes in various tissues of the mice. Arch Biochem Biophys373 :16 –22,2000[Medline]
  33. Quiles JL, Martinez E, Ibanez S, Ochoa JJ, Martin Y, Lopez-Frias M, Huertas JR, Mataix J: Ageing-related tissue-specific alterations in mitochondrial composition and function are modulated by dietary fat type in the rat. J Bioenerg Biomembr34 :517 –524,2002[Medline]
  34. Dulloo AG, Samec S: Uncoupling proteins: their roles in adaptive thermogenesis and substrate metabolism reconsidered. Br J Nutr86 :1 –18,2001[Medline]
  35. Petersen KF, Dufour S, Befroy D, Garcia R, Shulman GI: Impaired mitochondrial activity in the insulin-resistant offsprings of patient with type 2 diabetes. N Engl J Med350 :664 –671,2004[Abstract/Free Full Text]
  36. Weiss R, Dufour S, Taksali SE, Tamborlane WV, Petersen KF, Bonadonna RC, Boselli L, Babetta G, Allen K, Rife F, Savoye M, Dziura J, Sherwin R, Shulman GI, Caprio S: Prediabetes in obese youth: a syndrome of impaired glucose tolerance, severe insulin resistance, and altered myocellualr and abdominal fat partitioning. Lancet362 :951 –957,2003[Medline]
  37. Dulloo AG, Stock MJ, Solinas G, Boss O, Montani JP, Seydoux J: Leptin directly stimulates thermogenesis in skeletal muscle. FEBS Lett515 :109 –113,2002[Medline]

Add to CiteULike CiteULike   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 DiabetesHome page
M. Mogensen, K. Sahlin, M. Fernstrom, D. Glintborg, B. F. Vind, H. Beck-Nielsen, and K. Hojlund
Mitochondrial Respiration Is Decreased in Skeletal Muscle of Patients With Type 2 Diabetes
Diabetes, June 1, 2007; 56(6): 1592 - 1599.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
M. J. Holness, N. D. Smith, G. K. Greenwood, and M. C. Sugden
PPAR{alpha} activation reverses adverse effects induced by high-saturated-fat feeding on pancreatic beta-cell function in late pregnancy
Am J Physiol Endocrinol Metab, April 1, 2007; 292(4): E1087 - E1094.
[Abstract] [Full Text] [PDF]

Home page
 DiabetesHome page
R. Crescenzo, L. Lionetti, M. P. Mollica, M. Ferraro, E. D'Andrea, D. Mainieri, A. G. Dulloo, G. Liverini, and S. Iossa
Altered skeletal muscle subsarcolemmal mitochondrial compartment during catch-up fat after caloric restriction.
Diabetes, August 1, 2006; 55(8): 2286 - 2293.
[Abstract] [Full Text] [PDF]

Home page
 J. Gerontol. A Biol. Sci. Med. Sci.Home page
A. Alonso, R. Fernandez, M. Moreno, P. Ordonez, H. Gonzalez-Pardo, N. M. Conejo, F. Diaz, and C. Gonzalez
Positive Effects of 17{beta}-Estradiol on Insulin Sensitivity in Aged Ovariectomized Female Rats.
J. Gerontol. A Biol. Sci. Med. Sci., May 1, 2006; 61(5): 419 - 426.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
P. M. Thule, A. G. Campbell, D. J. Kleinhenz, D. E. Olson, J. J. Boutwell, R. L. Sutliff, and C. M. Hart
Hepatic insulin gene therapy prevents deterioration of vascular function and improves adipocytokine profile in STZ-diabetic rats
Am J Physiol Endocrinol Metab, January 1, 2006; 290(1): E114 - E122.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
T. R. Koves, P. Li, J. An, T. Akimoto, D. Slentz, O. Ilkayeva, G. L. Dohm, Z. Yan, C. B. Newgard, and D. M. Muoio
Peroxisome Proliferator-activated Receptor-{gamma} Co-activator 1{alpha}-mediated Metabolic Remodeling of Skeletal Myocytes Mimics Exercise Training and Reverses Lipid-induced Mitochondrial Inefficiency
J. Biol. Chem., September 30, 2005; 280(39): 33588 - 33598.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Iossa, S.
Right arrow Articles by Liverini, G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Iossa, S.
Right arrow Articles by Liverini, G.
Social Bookmarking
Add to CiteULike   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Diabetes Diabetes Care Clinical Diabetes Diabetes Spectrum