Properties of single motor units in medial gastrocnemius muscles of adult and old rats.

Kadhiresan, V.; Hassett, Cheryl A.; Faulkner, John A.

doi:10.1113/jphysiol.1996.sp021402

Cited by 135 publications

(113 citation statements)

References 34 publications

Supporting

Mentioning

109

Contrasting

Unclassified

Order By: Relevance

“…Previous age-related changing studies have shown that rat body weight peaks at age 60-72 weeks, and decreases thereafter (8). Studies have also found that the ratio of MHC I increases by about 20% in the rat soleus muscle at age 80-96 weeks (8), and that at the ages of 96-104 weeks, marked age-related changes occur in the remodeling of motor units, which appeared to involve denervation of fast muscle fibers followed by reinnervation of denervated fibers by axonal sprouting from slow fibers in the hindlimb muscles (7). The findings of this study suggest that structural changes occur at the muscle level around 100 weeks of age.…”

Section: Age-related Changes In Contractile Force Per Unit Cross-sectmentioning

confidence: 95%

Age-related changes in contraction and relaxation of rat diaphragm

et al. 2009

View full text Add to dashboard Cite

Age-related changes of physiological and biochemical properties were examined in the diaphragm muscle, which has particularly high activation compared to that of other skeletal muscles. The diaphragm from 10-week-, 50-week-and 100-week-old male Wistar rats were used to measure in vitro isometric contractile properties, sarcoplasmic reticulum (SR) Ca 2+ -ATPase activity, and myosin heavy chain (MHC) isoform composition. Although there were no significant differences in specific twitch tension of the diaphragm among the groups, there was significant reduction in specific tetanic tension in the 50-week to 100-week groups. The contraction time and 1/2 relaxation time of twitch contraction extended with aging, and significant differences were found between 10-week-old and 100-week-old diaphragms. Regarding the activity of SR Ca 2+ -ATPase, the pattern of age-related change was similar to that in the 1/2 relaxation time and there was a significant difference between 10-week-old and 100-week-old diaphragms. There was a significant increase in the relative composition of the MHC I isoform in 100-week-diaphragms compared to that in 10-week-old diaphragms and a concomitant decrease in the relative composition of fast myosin was noted. These findings demonstrated that older diaphragms have slower contraction and relaxation speeds, and these alterations were attributed to changes in SR Ca 2+ -ATPase activity and MHC isoform composition.Common age-related changes in physical functions include decreases in balance, visual acuity and hearing. With regard to skeletal muscles, changes such as muscle mass loss (18), lower muscle tension (9, 15), selective atrophy of fast-twitch fibers (16), and reduced mitochondrial enzyme and glycolytic enzyme activities (6) have been reported. These agerelated changes may cause falls, fractures and bed confinement, which are important social problems. Age-related changes in skeletal muscles have also been reported to affect not only the muscle fibers themselves, but also the oxygen supply to the cardiovascular system (22) and a decline in the number of spinal cord axons and nerve conduction velocity involved in contraction. Suppressing such age-related changes is considered important for successful aging. In rehabilitation, the diaphragm plays a wide variety of roles, including respiratory rehabilitation before and after surgery, home oxygen therapy for chronic obstructive pulmonary disease and cardiorespiratory responses in sports. Many rehabilitation therapists select abdominal breathing (diaphragmatic respiration) as the first-choice respiratory muscle exercise in acute and chronic patients. The diaphragm is the main action muscle of diaphragmatic respiration, and is always active in life maintenance; thus, when compared with other skeletal muscles, the diaphragm is more active. Hence, investigating chrono-

show abstract

Section: Age-related Changes In Contractile Force Per Unit Cross-sectmentioning

confidence: 95%

Age-related changes in contraction and relaxation of rat diaphragm

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Therefore investigations are important to determine how these changes progress with age to elucidate the underlying mechanisms for sarcopenia and muscle weakness that occurs with age. Mechanical and morphological properties of motor units in the aged rat have been reported previously (Edström and Larsson 1987;Einsiedel and Luff 1992;Kadhiresan et al 1996;Kanda and Hashizume 1989;Kanda et al 1986;Larsson 1995;Larsson andAnsved 1988, 1995;Larsson and Edström 1986;Pettigrew and Noble 1991). These studies have demonstrated that changes in the properties of motor units with advancing age are affected by multiple factors, such as degenerative changes of motoneuron and muscle fiber, the denervation and reinnervation process, transformation of muscle fibers, etc.…”

Section: Introductionmentioning

confidence: 95%

Progress of Age-Related Changes in Properties of Motor Units in the Gastrocnemius Muscle of Rats

Sugiura¹,

Kanda²

2004

Journal of Neurophysiology

View full text Add to dashboard Cite

Sugiura, Miho and Kenro Kanada. Progress of age-related changes in properties of motor units in the gastrocnemius muscle of rats. J Neurophysiol 92: 1357-1365, 2004. First published April 14, 2004 10.1152/jn.00947.2003. The mechanical properties of individual motor units in the medial gastrocnemius muscle, as well as the whole muscle properties and innervating motor nucleus, were investigated in dietary-restricted, male Fischer 344/DuCrj rats at ages of 4, 7, 12, 21/22, 27, 31, and 36 mo. The tetanic tension of the type S units continuously increased until the age of 36 mo. Those of type FF and FR units declined from 21/22 to 27 mo of age but did not change further while the whole muscle tension decreased greatly. The atrophy of muscle fibers, the decline in motoneuron number and axonal conduction velocity, and the decrease in the posttetanic potentiation of twitch contraction of motor units seemed to start after 21/22 mo of age and were accelerated with advancing age. Prolongation of twitch contraction time was evident for only type S and FR units in 36-moold rats. The fatigue index was greatly increased for type FF units in 36-mo-old rats. These findings indicated that the progress of changes in various properties occurring in the senescent muscle was different in terms of their time course and degree and also dependent on the types of motor unit. The atrophy and decrease in specific tension of muscle fibers affected the decline in tension output of motor units. This was effectively compensated for by the capture of denervated muscle fibers over time.

show abstract

“…The effects of aging on MHC isoform distribution have been studied in humans (Lexell et al, 1983;Lexell, 1995;Lexell et al, 1988;Larsson, 1983) and rodents (Caccia et al, 1979;Kanda and Hashizume, 1989;Kadhiresan et al, 1996). It is understood that aging brings about a loss in fibers (Lexell et al, 1988) and a decrease in type II/type I fiber number (Caccia et al, 1979;Larsson, 1983;Kanda and Hashizume, 1989) and fiber area ratio (Larsson, 1983;Arbanas et al, 2010); this age-related remodeling of motor units appears to involve denervation of fast fibers with reinnervation from nerves that innervate slow fibers (Kadhiresan et al, 1996). We thereby expect the MHC percentages in our study population to be skewed towards higher percentage MHC-1 amounts.…”

Section: Limitationsmentioning

confidence: 99%

Human skeletal muscle biochemical diversity

Tirrell

Cook

Carr

et al. 2012

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARY The molecular components largely responsible for muscle attributes such as passive tension development (titin and collagen), active tension development (myosin heavy chain, MHC) and mechanosensitive signaling (titin) have been well studied in animals but less is known about their roles in humans. The purpose of this study was to perform a comprehensive analysis of titin, collagen and MHC isoform distributions in a large number of human muscles, to search for common themes and trends in the muscular organization of the human body. In this study, 599 biopsies were obtained from six human cadaveric donors (mean age 83 years). Three assays were performed on each biopsy – titin molecular mass determination, hydroxyproline content (a surrogate for collagen content) and MHC isoform distribution. Titin molecular mass was increased in more distal muscles of the upper and lower limbs. This trend was also observed for collagen. Percentage MHC-1 data followed a pattern similar to collagen in muscles of the upper extremity but this trend was reversed in the lower extremity. Titin molecular mass was the best predictor of anatomical region and muscle functional group. On average, human muscles had more slow myosin than other mammals. Also, larger titins were generally associated with faster muscles. These trends suggest that distal muscles should have higher passive tension than proximal ones, and that titin size variability may potentially act to ‘tune’ the protein's mechanotransduction capability.

show abstract

Properties of single motor units in medial gastrocnemius muscles of adult and old rats.

Cited by 135 publications

References 34 publications

Age-related changes in contraction and relaxation of rat diaphragm

Age-related changes in contraction and relaxation of rat diaphragm

Progress of Age-Related Changes in Properties of Motor Units in the Gastrocnemius Muscle of Rats

Human skeletal muscle biochemical diversity

Contact Info

Product

Resources

About