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We tested the hypothesis that eccentric contractions activate mechanosensitive or stretch-activated ion channels (SAC) in skeletal muscles, producing increased cation conductance. Resting membrane potentials and contractile function were measured in rat tibialis anterior muscles after single or multiple exposures to a series of eccentric contractions. Each(More)
This report describes the histochemical and physiological properties of a rat skeletal muscle with a robust activity-dependent slow inward Ca2+ current. The muscle, the flexor digitorum brevis (FDB), is a small plantar flexor from the hindfoot. It is a homogeneous muscle consisting of approximately 90% fast-twitch oxidative-glycolytic (type IIA) fibers.(More)
Electromyography (EMG) and cinematography revealed a rapid, vibration-evoked startle response in intact larval lampreys. Vibratory stimuli produce simultaneous contraction of both sides of the body, and the response is lost after labyrinthectomy. Midbody EMGs exhibit a stimulus-response latency of 26.5 +/- 4.2 ms. Direct stimulation of the otic capsules,(More)
Anesthetized rats were subjected to a moderate degree of hemorrhagic shock, lowering their mean arterial pressure to approximately 50 mm Hg for approximately 100 min. At the end of the shock period, resting skeletal muscle transmembrane potentials had depolarized from a baseline value of -82 mV to -65 mV; intracellular water had increased by 13%; and(More)
BACKGROUND Stress, both acute and chronic, can impair cutaneous wound repair, which has previously been mechanistically ascribed to stress-induced elevations of cortisol. Here we aimed to examine an alternate explanation that the stress-induced hormone epinephrine directly impairs keratinocyte motility and wound re-epithelialization. Burn wounds are(More)
The previous demonstration of an increase and redistribution of adenylate cyclase activity in injured peripheral nerve suggests that an increase in neuronal cyclic AMP concentration could play a role in peripheral nerve regeneration. We report our finding that accumulating adenylate cyclase activity was translated into a twofold increase in cyclic AMP(More)
A recently described disorder in certain registered Quarter horses bears many clinical similarities to the muscle disease identified as hyperkalemic periodic paralysis (HPP) in humans. Pathological changes in membrane permeability or Na(+)-K+ pump activity have been proposed to produce the muscle depolarization and inexcitability that characterize the(More)
1. Motoneurones provide trophic control of some of the functional characteristics of skeletal muscle fibres. This study has been designed to test whether the adenylate cyclase: cyclic AMP system may offer one potential mechanism for the mediation of neurotrophic regulation. 2. The concentration of cyclic AMP was measured at various intervals after muscle(More)
Gated 31P-nuclear magnetic resonance followed the metabolic fluctuation in rat gastrocnemius muscle during a contraction cycle. Within 16 ms after stimulation, the phosphocreatine (PCr) level drops 11.3% from its reference state. The PCr minimum corresponds closely to the time of maximum force contraction. Pi increases stoichiometrically, while ATP remains(More)
This study was designed to define the age-related changes that occur in the F1 cross of the male Fischer 344 and brown Norway rats and to determine if these findings were associated with electrophysiologic abnormalities indicative of motor neuron loss. Contractility, morphologic, and histochemical studies were performed on the tibialis anterior muscles (TA)(More)