Histochemistry, innervation, capillary density, and mitochondrial volume of red and white muscle fibers isolated from a lizard, Varanus exanthematicus

1990 ◽  
Vol 68 (3) ◽  
pp. 476-481 ◽  
Author(s):  
Gabriel Mutungi
Keyword(s):  
White Muscle ◽  
Muscle Fibers ◽  
Capillary Density ◽  
The Other ◽  
Nerve Endings ◽  
Fiber Types ◽  
White Region ◽  
Monitor Lizard ◽  
Lower Vertebrates ◽  
Mitochondrial Volume

Fiber types in the iliofibularis muscle of the savannah monitor lizard, Varanus exanthematicus, have been characterized on the basis of their histochemical characteristics and nerve endings. Four types of fibers were identified, three of which were focally innervated and the other, multiply innervated. They corresponded to the fast glycolytic, fast oxidative glycolytic, slow oxidative, and tonic fiber types of other lower vertebrates. The fibers isolated from the white and most of the fibers from the red regions had well defined end plates. However, 15 to 20% of the fibers isolated from the red region possessed an average of 17 ± 0.5 end plates per fiber. These end plates were placed 922 ± 54 μm apart and poorly defined. The mitochondrial volume of fibers isolated from the red region (12 ± 0.5%) was six times that of fibers isolated from the white region (2 ± 0.1%). Myofibrillar volumes were similar in fibers isolated from the two regions (81 ± 0.6%, white; 77 ± 0.2%, red). However, the capillary density of fibers from the red region (932 ± 64/mm2) was four and one-half times that of fibers isolated from the corresponding white region (200 ± 35/mm2).

Oxidative capacity, blood flow, and capillarity of skeletal muscles

1980 ◽  
Vol 49 (4) ◽  
pp. 627-633 ◽  
Author(s):  
L. C. Maxwell ◽  
T. P. White ◽  
J. A. Faulkner
Keyword(s):  
Blood Flow ◽  
Skeletal Muscles ◽  
Muscle Blood Flow ◽  
Muscle Fibers ◽  
Capillary Density ◽  
Oxidative Capacity ◽  
Histochemical Demonstration ◽  
Capillary Endothelium ◽  
Fiber Types ◽  
Fiber Area

Our purpose was to test the hypothesis that the capillarity of mammalian skeletal muscles is correlated with the oxidate capacity of muscle fibers, or with the capacity for maximum blood flow. Capillarity of skeletal muscles from several species was determined using histochemical demonstration of phosphatase activity of capillary endothelium. Serial sections were incubated for succinate dehydrogenase activity as an indicator of muscle fiber oxidative capacity, and for myofibrillar ATPase activity. three types of muscle fibers were identified. Fiber area was determined by planimetry of projected cross sections. Succinate oxidase activity of whole homogenates was determined by differential respirometry. Muscle blood flow was determined experimentally or data were obtained from the literature. No consistent relation was observed for the different fiber types in the number of adjacent capillaries. Capillary density was negatively correlated with mean fiber area. Among adult animals of several species, skeletal muscles representing a 17-fold range of oxidative capacity demonstrated no relation between capillarity and oxidative capacity or muscle blood flow at maximum oxygen uptake. We find no support for relations between oxidative capacity of muscle blood flow and the capillarity of whole muscle or individual fibers and reject the hypothesis.

scholarly journals ULTRASTRUCTURE AND ADENOSINE TRIPHOSPHATASE ACTIVITY OF RED AND WHITE MUSCLE FIBERS OF THE CAUDAL REGION OF A FISH, SALMO GAIRDNERI

1972 ◽  
Vol 55 (1) ◽  
pp. 42-57 ◽  
Author(s):  
Asish C. Nag
Keyword(s):  
Electron Microscopy ◽  
Sarcoplasmic Reticulum ◽  
Adenosine Triphosphatase ◽  
White Muscle ◽  
Muscle Fibers ◽  
Salmo Gairdneri ◽  
Fiber Types ◽  
Surface Areas ◽  
Biochemical Studies ◽  
T System

Electron microscopy, together with quantitation using a tracing device linked to a digital computer, reveals that the red and white muscle fibers of Salmo gairdneri differ in diameter, organization of myofibrils, dimensions of myofilaments, volumes and surface areas of T system and sarcoplasmic reticulum, morphology of mitochondria, and content of mitochondria, lipid, and glycogen. Biochemical studies show that the ATPase activity of white fibers is three times that of the red fibers. Actomyosin content of red fibers is higher than that of the white fibers. The functional significance of these differences between two fiber types is discussed.

scholarly journals Oxidative capacity distribution in skeletal muscle fibers of the rat.

1994 ◽  
Vol 189 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M Philippi ◽  
A H Sillau
Keyword(s):  
Muscle Fibers ◽  
Oxidative Capacity ◽  
Volume Density ◽  
The Other ◽  
Isolated Mitochondria ◽  
Interfibrillar Mitochondria ◽  
Mitochondrial Volume ◽  
Mitochondrial Volume Density ◽  
The Difference ◽  
Subsarcolemmal Mitochondria

To study the distribution of oxidative capacity in muscle fibers, mitochondrial volume density and the oxidative capacity of isolated mitochondria were evaluated. Mitochondria were isolated from the subsarcolemmal and interfibrillar areas of the soleus (a muscle largely made up of slow oxidative fibers) and the gastrocnemius medial head (a muscle largely made up of fast glycolytic fibers) of the rat, and their oxidative capacities were evaluated using NADH- and FADH-generating substrates. In the soleus muscle, the subsarcolemmal mitochondria showed a lower oxidative capacity than interfibrillar mitochondria when NADH-generating substrates were used. This difference was not observed when FADH-generating substrates were used. In the gastrocnemius, there were no differences in the oxidative capacity of the subsarcolemmal and the interfibrillar mitochondria. Additionally, citrate synthase activity was found to be lower in mitochondria isolated from the subsarcolemmal area of the soleus than in the other mitochondrial preparations. These findings indicate that the difference in oxidative capacity of the isolated mitochondria is not related to differences in the inner mitochondrial membranes. Mitochondrial volume density was evaluated using electron micrographs of the subsarcolemmal and interfibrillar areas of slow oxidative fibers from the soleus and fast glycolytic fibers from the gastrocnemius. In the slow oxidative fibers, mitochondrial volume density in the subsarcolemmal area was four times higher than in the interfibrillar area. In the fast glycolytic fibers, mitochondrial volume densities in the subsarcolemmal and interfibrillar areas did not differ from that of the interfibrillar area of the slow oxidative fibers. The oxidative capacity of the tissue, calculated by multiplying the mitochondrial oxidative capacities by the mitochondrial volume densities, was 2-4 times higher in the subsarcolemmal areas of the soleus fibers than in the other areas studied. This was true in spite of the fact that the oxidative capacity of the subsarcolemmal mitochondria of the slow oxidative fibers was lower than those of the other mitochondrial populations studied. These results indicate that the difference in oxidative capacity between slow oxidative fibers and fast glycolytic fibers is the result of the much greater mitochondrial volume density in the subsarcolemmal area of the slow oxidative fibers.

Muscle fiber activity in carp as a function of swimming speed and muscle temperature

1984 ◽  
Vol 247 (2) ◽  
pp. R272-R279 ◽  
Author(s):  
L. C. Rome ◽  
P. T. Loughna ◽  
G. Goldspink
Keyword(s):  
White Muscle ◽  
Muscle Power ◽  
Muscle Fibers ◽  
Motor Units ◽  
Swimming Velocity ◽  
Muscle Temperature ◽  
Fiber Types ◽  
Thermal Dependence ◽  
Fast Twitch Muscle ◽  
Acute Changes

These experiments were performed to determine how ectothermal animals maintain their locomotory ability during acute changes in muscle temperature, despite the large thermal dependence of the mechanical properties of their muscle. The electrical activity of the red (slow-twitch) and white (fast-twitch) muscle fibers of carp was monitored while the carp swam at various speeds at 10 and 20 degrees C. The patterns of recruitment of different fiber types were similar at both temperatures. At low speeds only the red muscle was active, whereas at high speeds the white muscle was active as well. The swimming velocity at which white muscle was initially recruited increased from 26 cm/s at 10 degrees C to 46 cm/s at 20 degrees C. These results suggest that the order of recruitment of motor units was the same at 10 and 20 degrees C but that the recruitment occurred over a narrower range of speeds at the low temperature. Hence, to generate the muscle power required to swim at a certain velocity, fish recruit more muscle fibers, which include faster fiber types when their muscle is cold than when their muscle is warm.

Training-induced alterations in young and senescent rat diaphragm muscle

1992 ◽  
Vol 72 (4) ◽  
pp. 1506-1511 ◽  
Author(s):  
L. E. Gosselin ◽  
M. Betlach ◽  
A. C. Vailas ◽  
D. P. Thomas
Keyword(s):  
Citrate Synthase ◽  
Work Of Breathing ◽  
Muscle Fibers ◽  
Processing System ◽  
Capillary Density ◽  
Treadmill Running ◽  
Diaphragm Muscle ◽  
Type I ◽  
Fiber Types ◽  
Age Related

The current study sought to examine the effects of chronic endurance treadmill running on oxidative capacity and capillary density in specific diaphragm muscle fiber types in young (5 mo) and senescent (greater than or equal to 23 mo) female Fischer 344 rats. Both young and senescent animals trained at approximately 75% of maximal O2 consumption for 1 h/day 5 days/wk for 10 wk. Plantaris citrate synthase activity was significantly increased (P less than 0.01) in both young and old trained groups. Densitometric analysis of succinate dehydrogenase (SDH) activity in diaphragm type I, IIa, and IIb muscle fibers was done using a computerized image-processing system. There were no age-related differences in SDH activity between the young and old groups for any of the fiber types. In addition, SDH activity was found to be significantly increased (P less than 0.05) in all three fiber types in both the young and senescent trained animals compared with their sedentary counterparts. Fiber size and capillary density did not differ between young and senescent rats, nor did exercise affect this measure. Each fiber, irrespective of type, had an average of approximately four capillaries in contact with it. However, type IIb fibers had a significantly lower capillary density per unit area than type I or IIa muscle fibers. The results indicate that the senescent costal diaphragm maintains its ability to adapt to an increased metabolic demand brought about by locomotor exercise. Of further interest is the finding that training adaptations occurred in all three fiber types, suggesting that increased work of breathing from moderate exercise leads to recruitment of all three fiber types.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophoretic and functional identification of two troponin C isoforms in toad skeletal muscle fibers

2006 ◽  
Vol 290 (2) ◽  
pp. C515-C523 ◽  
Author(s):  
Brett O'Connell ◽  
Ronnie Blazev ◽  
Gabriela M. M. Stephenson
Keyword(s):  
Cardiac Muscle ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Troponin C ◽  
The Other ◽  
Differential Sensitivity ◽  
Fiber Types ◽  
Functional Identification ◽  
Cane Toad ◽  
Fast Twitch

The differential sensitivity of frog twitch and slow-tonic fibers to Ca2+ and Sr2+ suggests that these two fiber types express different troponin C (TnC) isoforms. To date, only one TnC isoform from anurans (resembling the mammalian fast-twitch isoform) has been isolated and characterized. In this study, we examined the possibility that anuran striated muscle contains more than one TnC isoform. Toward this end, we determined the TnC isoform composition of 198 single fibers from the rectus abdominis of the cane toad (a mixed slow-tonic and twitch muscle) and of toad cardiac muscle using a method that enables the identification of TnC isoforms on the basis of the effect of Ca2+ on their electrophoretic mobility. The fibers were typed according to their myosin heavy chain (MHC) isoform composition. The data indicate that striated muscle of the cane toad contains two TnC isoforms, one of which (TnC-t) is present in all fibers displaying only twitch MHC isoforms and the other of which (TnC-T/c) is present in fibers displaying the tonic MHC isoform and in cardiac muscle. For a subpopulation of 15 fibers, the TnC isoform composition was also compared with Ca2+ and Sr2+ activation characteristics. Fibers containing the TnC-T/c isoform were ∼3-fold more sensitive to Ca2+, ∼40-fold more sensitive to Sr2+, and responded to a ∼4.6-fold broader range of [Ca2+] than did fibers containing the TnC-t isoform. The Ca2+ activation properties of toad fibers containing the TnC-T/c isoform appear to be consistent with the previously reported physiological characteristics of amphibian slow-tonic muscle fibers.

The KATP channel Kir6.2 subunit content is higher in glycolytic than oxidative skeletal muscle fibers

2011 ◽  
Vol 301 (4) ◽  
pp. R916-R925 ◽  
Author(s):  
Krystyna Banas ◽  
Charlene Clow ◽  
Bernard J. Jasmin ◽  
Jean-Marc Renaud
Keyword(s):  
Skeletal Muscle ◽  
Cross Sections ◽  
Fiber Type ◽  
Energy Levels ◽  
Muscle Fibers ◽  
Metabolic Stress ◽  
Oxidative Capacity ◽  
Fiber Types ◽  
Fiber Damage ◽  
The Individual

It has long been suggested that in skeletal muscle, the ATP-sensitive K+ channel (KATP) channel is important in protecting energy levels and that abolishing its activity causes fiber damage and severely impairs function. The responses to a lack of KATP channel activity vary between muscles and fibers, with the severity of the impairment being the highest in the most glycolytic muscle fibers. Furthermore, glycolytic muscle fibers are also expected to face metabolic stress more often than oxidative ones. The objective of this study was to determine whether the t-tubular KATP channel content differs between muscles and fiber types. KATP channel content was estimated using a semiquantitative immunofluorescence approach by staining cross sections from soleus, extensor digitorum longus (EDL), and flexor digitorum brevis (FDB) muscles with anti-Kir6.2 antibody. Fiber types were determined using serial cross sections stained with specific antimyosin I, IIA, IIB, and IIX antibodies. Changes in Kir6.2 content were compared with changes in CaV1.1 content, as this Ca2+ channel is responsible for triggering Ca2+ release from sarcoplasmic reticulum. The Kir6.2 content was the lowest in the oxidative soleus and the highest in the glycolytic EDL and FDB. At the individual fiber level, the Kir6.2 content within a muscle was in the order of type IIB > IIX > IIA ≥ I. Interestingly, the Kir6.2 content for a given fiber type was significantly different between soleus, EDL, and FDB, and highest in FDB. Correlations of relative fluorescence intensities from the Kir6.2 and CaV1.1 antibodies were significant for all three muscles. However, the variability in content between the three muscles or individual fibers was much greater for Kir6.2 than for CaV1.1. It is suggested that the t-tubular KATP channel content increases as the glycolytic capacity increases and as the oxidative capacity decreases and that the expression of KATP channels may be linked to how often muscles/fibers face metabolic stress.

scholarly journals lncRNA-Six1 Is a Target of miR-1611 that Functions as a ceRNA to Regulate Six1 Protein Expression and Fiber Type Switching in Chicken Myogenesis

Cells ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 243 ◽  
Author(s):  
Manting Ma ◽  
Bolin Cai ◽  
Liang Jiang ◽  
Bahareldin Ali Abdalla ◽  
Zhenhui Li ◽  
...  
Keyword(s):  
Fiber Type ◽  
Muscle Fibers ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Proliferation And Differentiation ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Slow Twitch Fibers ◽  
Fast Twitch

Emerging studies indicate important roles for non-coding RNAs (ncRNAs) as essential regulators in myogenesis, but relatively less is known about their function. In our previous study, we found that lncRNA-Six1 can regulate Six1 in cis to participate in myogenesis. Here, we studied a microRNA (miRNA) that is specifically expressed in chickens (miR-1611). Interestingly, miR-1611 was found to contain potential binding sites for both lncRNA-Six1 and Six1, and it can interact with lncRNA-Six1 to regulate Six1 expression. Overexpression of miR-1611 represses the proliferation and differentiation of myoblasts. Moreover, miR-1611 is highly expressed in slow-twitch fibers, and it drives the transformation of fast-twitch muscle fibers to slow-twitch muscle fibers. Together, these data demonstrate that miR-1611 can mediate the regulation of Six1 by lncRNA-Six1, thereby affecting proliferation and differentiation of myoblasts and transformation of muscle fiber types.

Influence of acclimation temperature on mitochondrial DNA, RNA, and enzymes in skeletal muscle

1998 ◽  
Vol 275 (3) ◽  
pp. R905-R912 ◽  
Author(s):  
Brendan James Battersby ◽  
Christopher D. Moyes
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Dna ◽  
Steady State ◽  
Muscle Fiber ◽  
Copy Number ◽  
White Muscle ◽  
Fiber Types ◽  
Mitochondrial Enzymes ◽  
Dna Copy Number ◽  
Mitochondrial Content

Skeletal muscle fibers typically undergo modifications in their mitochondrial content, concomitant with alterations in oxidative metabolism that occur during the development of muscle fiber and in response to physiological stimuli. We examined how cold acclimation affects the mitochondrial properties of two fish skeletal muscle fiber types and how the regulators of mitochondrial content differed between tissues. After 2 mo of acclimation to either 4 or 18°C, mitochondrial enzyme activities in both red and white muscle were higher in cold-acclimated fish. No significant differences were detected between acclimation temperatures in the abundance of steady-state mitochondrial mRNA (cytochrome- c oxidase 1, subunit 6 of F0F1-ATPase), rRNA (16S), or DNA copy number. Steady-state mRNA for nuclear-encoded respiratory (adenine nucleotide translocase 1) and glycolytic genes showed high interindividual variability, particularly in the cold-acclimated fish. Although mitochondrial enzymes were 10-fold different between the two muscle types, mitochondrial DNA copy number differed only 4-fold. The relative abundance of mitochondrial mRNA and nuclear mRNA in red and white muscle reflected the differences in copy number of their respective genes. These data suggest that the response to physiological stimuli and determination of tissue-specific mitochondrial properties likely result from the regulation of nuclear-encoded genes.

scholarly journals Rate and timing of cortical responses driven by separate sensory channels

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Hannes P Saal ◽  
Michael A Harvey ◽  
Sliman J Bensmaia
Keyword(s):  
Computational Model ◽  
Relevant Information ◽  
Nerve Fibers ◽  
The Other ◽  
Fiber Types ◽  
Neural Signals ◽  
Neuronal Populations ◽  
Cortical Responses ◽  
Behaving Monkeys ◽  
Sense Of Touch

The sense of touch comprises multiple sensory channels that each conveys characteristic signals during interactions with objects. These neural signals must then be integrated in such a way that behaviorally relevant information about the objects is preserved. To understand the process of integration, we implement a simple computational model that describes how the responses of neurons in somatosensory cortex—recorded from awake, behaving monkeys—are shaped by the peripheral input, reconstructed using simulations of neuronal populations that reproduce natural spiking responses in the nerve with millisecond precision. First, we find that the strength of cortical responses is driven by one population of nerve fibers (rapidly adapting) whereas the timing of cortical responses is shaped by the other (Pacinian). Second, we show that input from these sensory channels is integrated in an optimal fashion that exploits the disparate response behaviors of different fiber types.

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