Skeletal muscle strength

Theophylline Uncertain phosphodiesterase inhibition t adenosine receptor antagonist Bronchodilation, cardiac stimulation, increased skeletal muscle strength (diaphragm) Asthma, COPD Oral duration 8-12 h but extended-release preparations often used Toxicity. Multiple (see text)... 

Functional neuromuscular electrical stimulation Increased skeletal muscle strength and endurance Decreased spasticity and muscle spasms Skeletal muscle relaxants Skeletal muscle relaxants Nonselective cholinergic agonists may stimulate the neuromuscular junction -... 

Use of AASs as a therapy for cardiovascular disease, particularly to increase skeletal muscle strength in patients who have congestive heart failure, a condition in which fluid congestion occurs as a result of heart failure, is also being studied. AASs have been proposed for treatment in the cachexia, or wasting that accompanies certain cancers, as well. 

Dantrolene is a hydantoin derivative related to phenytoin that has a unique mechanism of spasmolytic activity. In contrast to the centrally active drugs, dantrolene reduces skeletal muscle strength by interfering with excitation-contraction coupling in the muscle fibers. The normal contractile response involves release of calcium from its stores in the sarcoplasmic reticulum (see Figures 13-1 and 27-10). This activator calcium brings about the tension-generating interaction of actin with myosin. Calcium is released from the sarcoplasmic reticulum via a calcium channel, sometimes called the ryanodine receptor channel because the plant alkaloid ryanodine combines with a receptor on the channel protein and, in the case of the skeletal muscle channel, locks it in the open position. 

Neostigmine, pyridostigmine, edrophonium Myasthenia gravis, reversal of neuromuscular blockade Amplifies endogenous acetylcholine t skeletal muscle strength... 

A) Decreased blood pressure caused by hexamethonium Increased blood pressure caused by nicotine Increased skeletal muscle strength caused by neostigmine Tachycardia caused by exercise Tachycardia caused by infusion of acetylcholine Which of the following best describes the mechanism of action of scopolamine ... 

Buchner, D.M., Cress, M.E., de Lateur, B.f, and Wagner, E.H. Variability in the effect of strength training on skeletal muscle strength in older adults. J. Gerontol. 7 143-153,1993. 

Goswami R, Vatsa M, Sreenivas V, Singh U, Gupta N, Lakshmy R, et al. Skeletal muscle strength in young Asian Indian females after vitamin D and calcium supplementation a double-blind randomized controlled clinical trial. J CUn Endocrinol Metab December 2012 97(12) 4709-16. 

Describe the factors that influence the strength of skeletal muscle contraction including multiple motor unit summation, asynchronous motor unit summation, frequency of nerve stimulation, length-tension relationship, and diameter of the muscle fiber... 

Number of muscle fibers contracting. As the number of contracting muscle fibers increases, the strength of skeletal muscle contraction increases. Two major factors determine the number of muscle fibers activated at any given... 

Many factors influence the contractile activity of smooth muscle. The strength of contraction of multiunit smooth muscle may be enhanced by stimulation of a greater number of cells, or contractile units. This mechanism is directly comparable to motor-unit recruitment employed by skeletal muscle. As the number of contracting muscle cells increases, so does the strength of contraction. However, this mechanism is of no value in single-unit smooth muscle. Due to the presence of gap junctions, all of the muscle cells in the tissue are activated at once. 

Among nicotine-like effects on skeletal muscle were fascicula-tions (non-myasthenics2 only), increased strength (myasthenics only), decreased strength (non-myasthenics only), muscular cramps. 

The cholinesterase inhibitors have important therapeutic and toxic effects at the skeletal muscle neuromuscular junction. Low (therapeutic) concentrations moderately prolong and intensify the actions of physiologically released acetylcholine. This increases the strength of contraction, especially in muscles weakened by curare-like neuromuscular blocking agents... 

Muscle contraction responses to different patterns of nerve stimulation used in monitoring skeletal muscle relaxation. The alterations produced by a nondepolarizing blocker and depolarizing and desensitizing blockade by succinylcholine are shown. In the train of four (TOF) pattern, four stimuli are applied at 2 Hz. The TOF ratio (TOF-R) is calculated from the strength of the fourth contraction divided by that of the first. In the double burst pattern, three stimuli are applied at 50 Hz, followed by a 700 ms rest period and then repeated. In the posttetanic potentiation pattern, several seconds of 50 Hz stimulation are applied, followed by several seconds of rest and then by single stimuli at a slow rate (eg, 0.5 Hz). The number of detectable posttetanic twitches is the posttetanic count (PTC)., first posttetanic contraction. 

Sano, K.-I., Maeda, K., Oda, T., and Maeda, Y. (2000). The effect of single residue substitutions of serine-283 on the strength of head-to-tail interaction and actin binding properties of rabbit skeletal muscle a-tropomyosin. /. Biochem. 127, 1095-1102. 

Albuterol and terbutaline are also prepared in tablet form. One tablet two or three times daily is the usual regimen the principal adverse effects of skeletal muscle tremor, nervousness, and occasional weakness may be reduced by starting the patient on half-strength tablets for the first 2 weeks of therapy. 

Crawford, K., Flick, R., Close, L., Shelly, D., Paul, R., Bove, K., et al. (2002) Mice lacking skeletal muscle actin show reduced muscle strength and growth deficits and die during the neonatal period. Mol Cell Biol 22, 5887-5896. 

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