Tension and P liberation were determined at the same time in glycerol-extracted muscle fibers suspended in ATP solutions. In the relaxed state, produced by ATP in rather fresh preparations, P liberation was low, but somewhat higher than in normal resting muscle. On addition of small amounts of CaCl(2) the fibers gave a strong contraction during which P liberation was on the average about 5 time...

The spatial distribution of muscle fibers belonging to a motor unit was studied in the soleus and tibialis anterior muscles of adult cats. Motor unit fibers were depleted of their glycogen through repetitive stimulation of the motoneuron or of the functionally isolated motor axon. Subsequently, the position of depleted muscle fibers was mapped on serial cross sections taken along the length of ...

Flück, Martin, Silvia Schmutz, Matthias Wittwer, Hans Hoppeler, and Dominique Desplanches. Transcriptional reprogramming during reloading of atrophied rat soleus muscle. Am J Physiol Regul Integr Comp Physiol 289: R4 –R14, 2005; doi:10.1152/ajpregu.00833.2004.—The hypothesis was tested that differential, coregulated transcriptional adaptations of various cellular pathways would occur early with...

A three-dimensional human neuromuscular tissue model that mimics the physically separated structures of motor neurons and skeletal muscle fibers is presented.

Adult human muscle cultured in monolayer was cocultured with explants of 13-14-d-old rat embryo using (a) ventral spinal cord (VSC), (b) transverse section of whole spinal cord (WSC), and (c) WSC with dorsal root ganglia (DRG) attached (WSC + DRG). AChR clusters and AChE-positive patches, both at the nerve-muscle contacts, were studied at 5, 12, and 21 d of coculture with each of the 3 spinal c...

The mechanism through which the stresses developed in the diaphragmatic tissue during skeletal muscle contraction sustain local lymphatic function was studied in 10 deeply anesthetized, tracheotomized adult Wistar rats whose diaphragm was exposed after thoracotomy. To evaluate the direct effect of skeletal muscle contraction on the hydraulic intraluminal lymphatic pressures (Plymph) and lymphat...

The cat hindlimb contains several long, biarticular strap muscles composed of parallel muscle fascicles that attach to short tendons. Three of these muscles--sartorius, tenuissimus, and semitendinosus--were studied by dissecting individual gold-stained fibers and determining the surface distribution of acetylcholinesterase-stained end-plate zones. In each muscle, fascicles were composed of musc...

Histochemistry, immuno-histochemistry, gel electrophoresis of single muscle fibers and electromyography of aging muscles and nerves suggest that: i) denervation contributes to muscle atrophy, ii) impaired mobility accelerates the process, and iii) lifelong running protects against loss of motor units. Recent corroborating results on the muscle effects of Functional Electrical Stimulation (FES) ...

Muscle spindle density is extremely high in the deep muscles of the human neck. However, there is a paucity of information regarding the morphology and immunoreactivity of these muscle spindles. The objective of this study was to investigate the intrafusal fiber content and to assess the myosin heavy chain (MyHC) composition of muscle spindles from human deep neck muscles. In addition to the co...

Discharges of single afferent fibers from the primary endings of the soleus muscle spindles were recorded from thin dorsal root filaments in cats anesthetized with urethane and chloralose. The distal cut end of the ventral root was split into fine filaments to obtain functionally single fusimotor fibers. The fusimotor fibers obtained in this study were of the static type. The soleus muscle was ...