Fiber-type distribution in insect leg muscles parallels similarities and differences in the functional role of insect walking legs

Endurance trained ( n = 14) and untrained young men ( n = 15) were compared regarding the fatty acid profile of the vastus lateralis muscle after 8 wk on diets with a similar fatty acid composition. The skeletal muscle phospholipids in the trained group contained lower proportions of palmitic acid (16:0) (−12.4%, P < 0.001) and di-homo-γ-linolenic acid [20:3(n-6)] (−15.3%, P = 0.018), a lower n-6-to-n-3 ratio (−42.0%, P = 0.015), higher proportions of stearic acid (18:0) (+9.8%, P = 0.004) and sum of n-3 polyunsaturated fatty acids (+33.8%, P = 0.009), and a higher ratio between 20:4(n-6) to 20:3(n-6) (+18.4%, P = 0.006) compared with those in the untrained group. The group differences in 16:0, 20:3(n-6), 18:0/16:0, and 20:4(n-6)/20:3(n-6) were independent of fiber-type distribution. The trained group also showed a lower proportion of 16:0 (−7.9%, P < 0.001) in skeletal muscle triglycerides irrespective of fiber type. In conclusion, the fatty acid profile of the skeletal muscle differed between trained and untrained individuals, although the dietary fatty acid composition was similar. This difference was not explained by different fiber-type distribution alone but appears to be a direct consequence of changes in fatty acid metabolism due to the higher level of physical activity.

Download Full-text

Correlation between histochemically assessed fiber type distribution and isomyosin and myosin heavy chain content in porcine skeletal muscles.

Journal of Animal Science ◽

10.2527/1999.7782104x ◽

1999 ◽

Vol 77 (8) ◽

pp. 2104 ◽

Cited By ~ 24

Author(s):

G Bee ◽

M B Solomon ◽

S M Czerwinski ◽

C Long ◽

V G Pursel

Keyword(s):

Myosin Heavy Chain ◽

Heavy Chain ◽

Skeletal Muscles ◽

Fiber Type ◽

Type Distribution ◽

Fiber Type Distribution

Download Full-text

Changes in skeletal muscle in males and females following endurance training

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y01-008 ◽

2001 ◽

Vol 79 (5) ◽

pp. 386-392 ◽

Cited By ~ 119

Author(s):

S L Carter ◽

C D Rennie ◽

S J Hamilton ◽

M A Tarnopolsky

Keyword(s):

Skeletal Muscle ◽

Endurance Training ◽

Endurance Exercise ◽

Fiber Type ◽

Oxidative Potential ◽

Muscle Enzyme ◽

Type Distribution ◽

Endurance Exercise Training ◽

Fiber Type Distribution ◽

Males And Females

Gender differences in substrate selection have been reported during endurance exercise. To date, no studies have looked at muscle enzyme adaptations following endurance exercise training in both genders. We investigated the effect of a 7-week endurance exercise training program on the activity of β-oxidation, tricarboxylic acid cycle and electron transport chain enzymes, and fiber type distribution in males and females. Training resulted in an increase in [Formula: see text]O2peak for both males and females of 17% and 22%, respectively (P < 0.001). The following muscle enzyme activities increased similarly in both genders: 3-β-hydroxyacyl CoA dehydrogenase (38%), citrate synthase (41%), succinate-cytochrome c oxidoreductase (41%), and cytochrome c oxidase (COX; 26%). The increase in COX activity was correlated (R2 = 0.52, P < 0.05) with the increase in [Formula: see text]O2peak/ fat free mass. Fiber area, size, and % area were not affected by training for either gender, however, males had larger Type II fibers (P < 0.05) and females had a greater Type I fiber % area (P < 0.05). Endurance training resulted in similar increases in skeletal muscle oxidative potential for both males and females. Training did not affect fiber type distribution or size in either gender.Key words: endurance training, oxidative potential, gender.

Download Full-text

Workshop no. 1. Alternate metabolic pathways in protozoan energy metabolism

Parasitology ◽

10.1017/s0031182000150073 ◽

1981 ◽

Vol 82 (4) ◽

pp. 1-30 ◽

Cited By ~ 4

Keyword(s):

Energy Metabolism ◽

Metabolic Pathways ◽

Functional Role ◽

High Energy ◽

Strictly Anaerobic ◽

Factors Affecting ◽

Subcellular Compartmentation ◽

Similarities And Differences ◽

Metabolic Behaviour

The purpose of this workshop was to collect together colleagues investigating the intermediary metabolism of protozoa, with a view to discussing those pathways involved in energy metabolism and the production of ATP and other high-energy compounds, together with the factors affecting energy balance. The aspects of energy metabolism chosen for discussion comprised the metabolic pathways ranging from the strictly anaerobic to highly oxidative; subcellular compartmentation of these pathways within the protozoa; the functional role of these pathways including a consideration of aero-tolerance; and the use of inhibitors as biochemical probes and potential chemotherapeuticagents. Hopefully this approach has produced a broad 'over-view' of important areas of protozoan energy metabolism which will enable both the specialist and non-specialist to appreciate the similarities and differences between the metabolic behaviour of a range of protozoa.

Download Full-text

Histochemical and physiological characteristics of the rat diaphragm

Journal of Applied Physiology ◽

10.1152/jappl.1985.58.4.1085 ◽

1985 ◽

Vol 58 (4) ◽

pp. 1085-1091 ◽

Cited By ~ 60

Author(s):

J. M. Metzger ◽

K. B. Scheidt ◽

R. H. Fitts

Keyword(s):

Fiber Type ◽

Contractile Properties ◽

Effect Of Temperature ◽

Type I ◽

Force Frequency ◽

Rat Diaphragm ◽

Shortening Velocity ◽

Type Distribution ◽

Adult Rat ◽

Fiber Type Distribution

The histochemical and contractile characteristics of the adult rat diaphragm were determined. Based on enzyme histochemistry, the rat diaphragm contained 40% type I, 27% type IIa, and 34% type IIb fibers. There were significantly more type I fibers in the ventral costal (VEN) compared with the crural (CRU) region of the muscle and a slightly higher percentage of type I's on the thoracic relative to the abdominal surface. The contractile properties and the effect of temperature (Q10) were similar in the VEN and CRU regions. Increasing temperature produced higher isometric peak tetanic tension, whereas twitch tension, contraction, and one-half relaxation time all decreased. The maximal shortening velocity increased linearly from 22 and 30 degrees C, then plateaued before decreasing between 35 and 37 degrees C. The VEN and CRU force-velocity curves became less concave as temperature increased from 22 to 35 degrees C. Furthermore, the force-frequency relation of both regions was shifted to the right as temperature increased. The isometric and isotonic contractile properties and fiber type distribution are similar in the VEN and CRU regions of the diaphragm. The rat diaphragm is clearly heterogeneous in fiber type distribution and functionally lies intermediate between slow- and fast-twitch limb skeletal muscles.

Download Full-text