Effects of external calcium on contractile responses in rat extensor digitorum longus muscles after sciatic nerve injury at birth

Louboutin, Jean‐Pierre; Fichter‐Gagnepain, Valérie; Noireaud, Jacques

doi:10.1002/(sici)1097-4598(199611)19:11<1421::aid-mus6>3.3.co;2-5

Cited by 1 publication

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“…Partially denervated fibers represent up to 35% of fibers in aged muscle (Wang, et al, 2005), and we believe this diminished or altered state of innervation to be important in the external Ca 2+ -dependent contraction phenomenon. Indeed, dependence on external Ca 2+ to maintain tetanic force has been shown in muscles that have undergone nerve damage and repair (Louboutin, et al, 1996,Pereon, et al, 1997. The recognition that denervation may be the underlying cause of, specifically, age-related external Ca 2+ dependence is important because it is a physiological indicator of the extension of muscle fiber denervation in aged muscle (i.e., ~50% of muscle fibers).…”

Section: Igf-1 and Muscle Innervation In Aged Micementioning

confidence: 99%

Motor neuron targeting of IGF-1 attenuates age-related external Ca2+-dependent skeletal muscle contraction in senescent mice

Payne

Messi

Zheng

et al. 2007

Experimental Gerontology

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A population of fast muscle fibers from aging mice is dependent on external Ca 2+ to maintain tetanic force during repeated contractions. We hypothesized that age-related denervation in muscle fibers plays a role in initiating this contractile deficit, and that prevention of denervation by IGF-1 overexpression would prevent external Ca 2+ -dependent contraction in aging mice. IGF-1 overexpression in skeletal muscle prevents age-related denervation, and prevented external Ca 2+ -dependent contraction in this work. To determine if the effects of IGF-1 overexpression are on muscle or nerve, aging mice were injected with a tetanus toxin fragment-C (TTC) fusion protein that targets IGF-1 to spinal cord motor neurons. This treatment prevented external Ca 2+ -dependent contraction. We also show evidence that injections of the IGF-1-TTC fusion protein prevent age-related alterations to the nerve terminals at the neuromuscular junctions. We conclude that the slow agerelated denervation of fast muscle fibers underlies dependence on external Ca 2+ to maintain tetanic force in a population of muscle fibers from senescent mice.

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Section: Igf-1 and Muscle Innervation In Aged Micementioning

confidence: 99%