Respiratory capacity of white, red, and intermediate muscle: adaptative response to exercise

Baldwin, K. M.; Klinkerfuss, GH; Terjung, R. L.; Mole, P. A.; Holloszy, J. O.

doi:10.1152/ajplegacy.1972.222.2.373

Cited by 377 publications

(169 citation statements)

References 20 publications

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“…We therefore consider that, in the absence of any suitable alternative for identifying fibres that have been stimulated, our criterion is valid. The increase in HK activity with little or no change in PFK activity is similar to that observed following endurance training (Baldwin et al 1972;Green et al 1983) and chronic stimulation (Pette et al 1973) in animals, where the HK II isoform appears to be mainly affected (Weber & Pette, 1988). This response may be initiated by an increase in the uptake of glucose during repetitive muscle activation prior to development of a greater energy supply from fatty acid metabolism, or may result from a greater delivery of glucose due to the improved flow capacity of an expanded capillary bed.…”

Section: Discussionsupporting

confidence: 75%

Selective long-term electrical stimulation of fast glycolytic fibres increases capillary supply but not oxidative enzyme activity in rat skeletal muscles

Egginton¹,

Hudlická²

2000

Exp. Physiol.

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Section: Discussionsupporting

confidence: 75%

Selective long-term electrical stimulation of fast glycolytic fibres increases capillary supply but not oxidative enzyme activity in rat skeletal muscles

Egginton¹,

Hudlická²

2000

Exp. Physiol.

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“…It has been known for many years that endurance exercise induces an adaptive increase in skeletal muscle mitochondria with increases in the capacity to oxidize carbohydrate and fat and generate ATP (1)(2)(3)(4)(5)(6). This adaptation plays a major role in the exercise-training-induced increase in endurance by decreasing the disturbance in homeostasis induced by muscle contractions/strenuous exercise, (47,48).…”

Section: Discussionmentioning

confidence: 99%

“…This adaptation results in increases in the capacities to oxidize carbohydrate and fat and generate ATP (3)(4)(5)(6). The transcription coactivator peroxisome proliferatoractivated receptor ␥ coactivator-1␣ (PGC-1␣) 4 regulates the coordinated expression of the mitochondrial genome and of the nuclear genes encoding mitochondrial enzymes (7)(8)(9).…”

mentioning

confidence: 99%

Calcium Induces Increases in Peroxisome Proliferator-activated Receptor γ Coactivator-1α and Mitochondrial Biogenesis by a Pathway Leading to p38 Mitogen-activated Protein Kinase Activation

Wright¹,

Geiger²,

Han

et al. 2007

Journal of Biological Chemistry

262

204

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Previous studies have shown that raising cytosolic calcium in myotubes induces increases in peroxisome proliferator-activated receptor ␥ coactivator-1␣ expression and mitochondrial biogenesis. This finding suggests that the increases in cytosolic calcium in skeletal muscle during exercise may mediate the exercise-induced increase in mitochondria. The initial aim of this study was to determine whether raising calcium in skeletal muscle induces the same adaptations as in myotubes. We found that treatment of rat epitrochlearis muscles with a concentration of caffeine that raises cytosolic calcium to a concentration too low to cause contraction induces increases in peroxisome proliferator-activated receptor ␥ coactivator-1␣ expression and mitochondrial biogenesis. Our second aim was to elucidate the pathway by which calcium induces these adaptations. Raising cytosoliccalciumhasbeenshowntoactivatecalcium/calmodulindependent protein kinase in muscle. In the present study raising cytosolic calcium resulted in increases in phosphorylation of p38 mitogen-activated protein kinase and activating transcription factor-2, which were blocked by the calcium/calmodulindependent protein kinase inhibitor KN93 and by the p38 mitogen-activated protein kinase inhibitor SB202190. The increases in peroxisome proliferator-activated receptor ␥ coactivator-1␣ expression and mitochondrial biogenesis were also prevented by inhibiting p38 activation. We interpret these findings as evidence that p38 mitogen-activated protein kinase is downstream of calcium/calmodulindependent protein kinase in a signaling pathway by which increases in cytosolic calcium lead to increases in peroxisome proliferator-activated receptor ␥ coactivator-1␣ expression and mitochondrial biogenesis in muscle.

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“…Oxidative fibers have a higher capacity to store and utilize lipids and higher mitochondrial content and activities of respiratory enzymes (3,19,24). Indeed, the increase in skeletal muscle TG content with endurance exercise occurs primarily in oxidative muscle (22).…”

Section: Discussionmentioning

confidence: 99%

Increased lipid accumulation and insulin resistance in transgenic mice expressing DGAT2 in glycolytic (type II) muscle

Levin¹,

Monetti²,

Watt³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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October 16, 2007; doi:10.1152/ajpendo.00158.2007.-Insulin resistance and type 2 diabetes are frequently accompanied by lipid accumulation in skeletal muscle. However, it is unknown whether primary lipid deposition in skeletal muscle is sufficient to cause insulin resistance or whether the type of muscle fiber, oxidative or glycolytic fiber, is an important determinant of lipid-mediated insulin resistance. Here we utilized transgenic mice to test the hypothesis that lipid accumulation specifically in glycolytic muscle promotes insulin resistance. Overexpression of DGAT2, which encodes an acyl-CoA:diacylglycerol acyltransferase that catalyzes triacylglycerol (TG) synthesis, in glycolytic muscle of mice increased the content of TG, ceramides, and unsaturated long-chain fatty acyl-CoAs in young adult mice. This lipid accumulation was accompanied by impaired insulin signaling and insulin-mediated glucose uptake in glycolytic muscle and impaired whole body glucose and insulin tolerance. We conclude that DGAT2-mediated lipid deposition specifically in glycolytic muscle promotes insulin resistance in this tissue and may contribute to the development of diabetes. acyl-CoA:diacylglycerol acyltransferase 2; skeletal muscle; glycolytic fibers; triacylglycerols INSULIN RESISTANCE AND TYPE 2 DIABETES are frequently associated with lipid accumulation in skeletal muscle (30,48,56). In humans, increased intramyocellular lipid content correlates with insulin resistance (45). In both rodents and humans, intravenous infusion of lipid or chronic high-fat feeding results in the accumulation of lipids, including triacylglycerol (TG), and insulin resistance in skeletal muscle (6,12,23,33). Mice with genetic modifications that increase muscle lipids, such as muscle-specific overexpression of lipoprotein lipase and CD36 (26, 31), also exhibit insulin resistance. On the other hand, endurance exercise training increases TG deposition in skeletal muscle and is associated with increased insulin sensitivity (22). Thus, the relationship between lipid accumulation in muscle and insulin resistance remains incompletely understood.One factor that has not been extensively studied with respect to intramuscular lipid deposition is fiber type. Skeletal muscle is composed mainly of two types of fibers, oxidative (type I, slow-twitch, red) and glycolytic (type II, fast-twitch, white), whose proportions can vary greatly. Marathon runners, for example, have ϳ80% type I fibers in leg muscles (21), whereas sprinters have ϳ75% type II fibers (14). It is unknown whether the type of muscle fiber is an important consideration in lipid-associated insulin resistance. Oxidative muscle normally stores more TG and is more insulin sensitive than glycolytic muscle (43,44). Moreover, endurance training increases both TG content and insulin sensitivity in oxidative muscle (22). Thus, increased lipid content in oxidative muscle may not be detrimental. On the other hand, glycolytic muscle stores less TG and is less insulin sensitive than oxidative muscle (43,44). The re...

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Respiratory capacity of white, red, and intermediate muscle: adaptative response to exercise

Cited by 377 publications

References 20 publications

Selective long-term electrical stimulation of fast glycolytic fibres increases capillary supply but not oxidative enzyme activity in rat skeletal muscles

Selective long-term electrical stimulation of fast glycolytic fibres increases capillary supply but not oxidative enzyme activity in rat skeletal muscles

Calcium Induces Increases in Peroxisome Proliferator-activated Receptor γ Coactivator-1α and Mitochondrial Biogenesis by a Pathway Leading to p38 Mitogen-activated Protein Kinase Activation

Increased lipid accumulation and insulin resistance in transgenic mice expressing DGAT2 in glycolytic (type II) muscle

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