Muscle Function

Muscimol [2763-96-4] Muscle function Musde palsy Muscle relaxant Muscone [541-91-3]... 

Ca " concentration, termed hypocalcemia, excitabihty increases. If this condition is not corrected, the symptoms of tetany, ie, muscular spasm, tremor, and even convulsions, can appear. Too great an increase in Ca " concentration, hypercalcemia, may impair muscle function to such an extent that respiratory or cardiac failure may occur. 

Smooth muscle cell activity is in general under neural control. Thus, the many transmitters of the autonomic nervous system are paired with receptors on the smooth muscle cell membrane. One of the current questions about smooth muscle function is What intracellular processes are the different transmitters modulating in the smooth muscle cells, in addition to their effects on the contractile state ... 

In terms of muscle function, muscle is very adaptable. Depending on the type of stimulation, muscle can either twitch or contract tetanically for a variable length of time. If the ends are held fixed, then it contracts isometrically and the force produced is maximal. If one or both ends of the muscle are not held fixed then the muscle is able to shorten. The muscle can shorten at a fixed load (isotonic contraction) where the velocity of shortening is also constant. Power output (force X velocity) is maximum where the velocity of shortening is about one third of the maximal rate. Finally, the muscle can shorten at maximum velocity (unloaded shortening). However, the molecular basis of the interaction of myosin with actin to produce force, or shortening, is the same in each case. 

Edwards, R.H.T. (1981). Human muscle function and fatigue. In Human Muscle Fatigue Physiological Mechanisms (Porter, R. Whelan, J., eds.), pp. 1-18, Pitman, London. 

Figure 31-3. Arginine, ornithine, and proline metabolism. Reactions with solid arrows all occur in mammalian tissues. Putrescine and spermine synthesis occurs in both mammals and bacteria. Arginine phosphate of invertebrate muscle functions as a phosphagen analogous to creatine phosphate of mammalian muscle (see Figure 31-6).

Skeletal muscle functions under both aerobic (resting) and anaerobic (eg, sprinting) conditions, so both aerobic and anaerobic glycolysis operate, depending on conditions. 

Based on a study conducted with 40 healthy volunteers, Lignell reported the effect of astaxanthin on mammalian muscle function. Volunteers received one capsule of 4 mg astaxanthin each morning in association with food. No significant difference was observed between the treatment and placebo groups in any physical parameters measured. 

LigneU, S., Medicament for improvement of duration of muscle function or treatment of muscle disorders or diseases, AstaCarotene AB, Sweden, US Patent 6245218, 2001. 

In recent years free-radical species have been implicated in the pathogenesis of a wide variety of disorders (see Hal-liwell and Gutteridge, 1989), and attention has been drawn to the possibility that these agents might mediate some of the effects of excessive or unaccustomed exercise on muscle function and structure. In addition, free radicals may play a role in a number of muscle diseases. The aim of this short review is to examine these areas, drawing particular attention to those situations where the role of free radicals is controversial or where further studies are required. 

In conclusion, it is apparent that the lack of definitive methods for assessment of free radicals in muscle and other tissues inhibits clear conclusions to be drawn concerning the relevance (or lack of relevance) of these substances in muscle pathology. In particular, the relevance of free radicals to the deficits in muscle function (fatigue and damage), which occur with exercise, is still unclear despite extensive study. This and other areas require much further examination. 

Lopes, J. M., Aubier, M., Jardin, J., Aranda, J. V., and Macklem, P. T., Effects of caffeine on skeletal muscle function before and after fatigue, Journal of Applied Physiology, 54, 1303, 1983. 

H27. Hollenberg, S. M., and Cunnion, R. E., Endothelial and vascular smooth muscle function in sepsis. J. Crit. Care 9,262-280 (1994). 

Although skeletal muscle comprises the bulk of muscle tissue in the body, smooth muscle is far more important in terms of homeostasis. Most smooth muscle is found in the walls of tubes and hollow organs. Contraction and relaxation of the smooth muscle in these tissues regulates the movement of substances within them. For example, contraction of the smooth muscle in the wall of a blood vessel narrows the diameter of the vessel and leads to a decrease in the flow of blood through it. Contraction of the smooth muscle in the wall of the stomach exerts pressure on its contents and pushes these substances forward into the small intestine. Smooth muscle functions at a subconscious level and is involuntary. It is innervated by the autonomic nervous system, which regulates its activity. 

Vallance, BA (1999) The immunomodulation of intestinal smooth muscle function. PhD thesis, McMaster University, Canada. 

Vermillion, D.L., Ernst, P.B. and Collins, S.M. (1991) T-lymphocyte modulation of intestinal muscle function in the Trichinella-infected rat. Gastroenterology 101, 31-38. 

A high sodium intake and increased circulating natriuretic hormone inhibition of intracellular sodium transport, resulting in increased vascular reactivity and a rise in BP and / Increased intracellular concentration of calcium, leading to altered vascular smooth muscle function and increased peripheral vascular resistance. 

Assessing the outcome of EN includes monitoring objective measures of body composition, protein and energy balance, and subjective outcome for physiologic muscle function and wound healing. 

Suxamethonium sensitivity," prolonged paralysis of respiratory muscle function caused by failure to cleave the short-acting muscle relaxant succinylcholine widely used in anesthesia, was made testable with a simple bedside assay in 1968 (Motulsky and Morrow). However, that test was not incorporated widely into practice. Most anesthesiologists felt they could simply monitor all patients and "bag" those not resuming respiratory action, without testing for a trait that would be found in only one of 2000 patients. 

Taggart MJ, Wray S 1997 Agonist mobilization of sarcoplasmic reticular calcium in smooth muscle functional coupling to the plasmalemmal Na+/Ca2+ exchanger. Cell Calcium 22 333-341... 

Blaustein MP, Golovina VA, Song H et al 2002 Organization of Ca2+ stores in vascular smooth muscle functional implications. In Role of the sarcoplasmic reticulum in smooth muscle. Wiley, Chichester (Novartis Found Symp 246) p 125-141 Karaki H, Ozaki H, Hori M et al 1997 Calcium movements, distribution and function in smooth muscle. Pharmacol Rev 49 157-230... 

Organization of Ca2+ stores in vascular smooth muscle functional implications... 

The sarcoplasmic reticulum and smooth muscle function evidence from transgenic mice... 

Modulation of the SR Ca2+ ATPase by PLB perhaps provides the clearest evidence of the significance of the SR to smooth muscle Ca2+ homeostasis and contractility. It also offers some cautions since the effects of modulation of SR function were clearly dependent on the smooth muscle tissue studied. In summary, genetically altered mouse models provide a new approach for assessing the physiological significance of the SR to smooth muscle function in vivo. 

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