The relationship between muscle length, integrated electromyographic activity, and torque of the biceps femoris muscle was investigated while the line of action of the muscle at the knee was held constant. Muscle length was changed by varying the hip joint angle. Sixteen subjects produced 1) maximal isometric contractions, 2) contractions with constant submaximal torque, and 3) contractions wit...

Nicotinic acetylcholine receptors (nAChRs) localized to excitatory longitudinal muscle motoneurons were studied in segments of guinea pig ileum maintained in vitro. Longitudinal muscle contractions caused by the nAChRs agonists, dimethylphenylpiperazinium (DMPP), nicotine, and cytisine were measured using isometric strain gauge transducers. In normal Krebs' solution, the nAChR agonists caused c...

The relationship between neurogenic responses of longitudinal and circular muscle was studied by measuring contractions and EMG or nonadrenergic, non-cholinergic (NANC) relaxations and NANC inhibitory junction potentials in different preparations of the guinea-pig ileum. NANC relaxation of longitudinal muscle was observed also without any preceding or concomitant circular muscle contraction rul...

Skeletal muscles can be injured by lengthening contractions, when the muscles are stretched while activated. Lengthening contractions produce structural damage that leads to the degeneration and regeneration of damaged muscle fibers by mechanisms that have not been fully elucidated. Reactive oxygen species (ROS) generated at the time of injury may initiate degenerative or regenerative processes...

Many patients with upper motoneuron lesion have difficulty in making useful muscle contractions due to weak and atrophied muscles. The feasibility of using functional electrical stimulation (FES) for muscle activation to restore gait in these patients has been demonstrated. This is possible because most of these patients have intact peripheral nerves below their level of injury that can be stim...

The purpose of this investigation was to examine the effect of rhythmic tetanic skeletal muscle contractions on peak muscle perfusion by using spontaneously perfused canine gastrocnemii in situ. Simultaneous pulsatile blood pressures were measured by means of transducers placed in the popliteal artery and vein, and pulsatile flow was measured with a flow-through-type transit-time ultrasound pro...

PURPOSE The rabbit iris sphincter muscle is innervated by cholinergic and tachykinergic nerves that regulate its tone. To clarify the involvement of nitric oxide (NO) in the postsynaptic regulation of the rabbit iris sphincter muscle tone, the authors examined the effects of NO-related agents on the cholinergic contraction induced by carbamylcholine (carbachol) and the tachykinergic contraction...

BACKGROUND Critical illness is associated with muscle weakness leading to long-term functional limitations. OBJECTIVES To assess the reliability of a novel method for evaluating fatigability of the quadriceps muscle in noncooperating healthy subjects. METHODS On two occasions, separated by seven days, nonvoluntary isometric contractions (twitch and tetanic) of the quadriceps femoris muscle ...

1. A period of stimulation of intrinsic or extrinsic nerves to intestinal muscle is often followed by a secondary contraction. In the present work, the basis for such secondary contractions in the longitudinal muscle of the large bowel of guinea-pigs and rabbits was examined.2. In general, the action of cholinergic nerves did not contribute significantly to the secondary contractions. Concentra...

chorea is brief, quasi-purposeful, irregular muscle contractions, not repetitive or rhythmic, but flows from one muscle to the next and athetosis is slow, writhing, continuous, worm-like movements of distal extremities (chiefly the fingers) which show bizarre positioning without posturing. metabolic causes have been documented earlier, note worthy of that being diabetes. choreoathetosis has bee...