Skinned Fiber

Other patents (81,82) coveted the preparation of cellulose solutions using NMMO and speculated about their use as dialysis membranes, food casings (sausage skins), fibers, films, paper coatings, and nonwoven binders. NMMO emerged as the best of the amine oxides, and its commercial potential was demonstrated by American Enka (83,84). Others (85) have studied the cellulose-NMMO system in depth one paper indicates that further strength increases can be obtained by adding ammonium chloride or calcium chloride to the dope (86). 

A skinned fiber is a muscle fiber, the sarcolemma of which has been mechanically removed or which is made freely permeable to small molecules, such as Ca2+, Mg2+, EGTA, ATP, soluble enzymes and others by a chemical agent (saponin, (3-escin or Staphylococcus a-toxin). The organization of the sarcoplasmic reticulum (SR) and myofibrils is kqrt as they are in the living muscle. 

However, by carrying out experiments with skinned fibers, the composition of the solution surrounding the myofibrils can be controlled and the mechanical properties of the muscle fiber can be related more easily to the biochemistry of force... 

Stephenson, E. W., Activation of fast skeletal muscle Contribution of studies on skinned fibers, American Journal of Physiology, 240, Cl, 1981. 

Bore skin fibers, 16 22 Boric acid, 4 249-255. See also Boron oxides, boric acid, and borates analysis, 4 255... 

Kawai, M., and Halvorson, H. R. (1991). Two step mechanism of phosphate release and the mechanism of force generation in chemically skinned fibers of rabbit psoas muscle. Biophys. J. 59, 329-342. 

Use Bleaching skins, fibers, oils disinfectants mordant (wool) batteries photography printing source of oxygen (dyeing) water purification oxidizing agent. 

The identification and development of specific inhibitors of MLCK could provide valuable experimental tools for exploring physiological functions of MLCK and myosin phosphorylation in smooth muscle and nonmuscle cells. Although inhibitors that act by binding calmodulin have been used experimentally, their usefulness is limited because they inhibit other calmodulin-dependent enzymes in tissues and cells (Asano and Stull, 1985 Nakanishi et al., 1992). Therefore, attempts have been made to develop novel reagents that inhibit MLCK activity directly. ML-9 [l-(5-chloronaphthalenesulfonyl)-lH-hexahydro-l, 4-diazepine] inhibits purified smooth muscle MLCK competitively with respect to ATP (Saitoh et al., 1987). Predictably, it inhibits RLC phosphorylation in ac-tomyosin, skinned fibers, and smooth muscle strips (Ishikawa et al., 1988). However, ML-9 also inhibits other protein kinases, so its specificity under different experimental conditions needs to be established. 

A systematic evaluation of phosphatase types in different smooth muscles has not been carried out. Most of the biochemical characterizations have used gizzard as a source (for practical considerations) and only a few other smooth muscles have been studied (see Table I). A larger variety of muscle have been studied using more physiological approaches, either intact or skinned fibers, and these have frequently demonstrated existence of myosin phosphatase but generally have not identified the phosphatase involved. 

Fibers treated in the described way respond rapidly to increasing Ca + concentrations. Threshold concentrations are around 2 x 10 7 M Ca + and maximum contraction was observed at 10 (jlM Ca +. Maximal force is comparable to or even larger than that observed before saponin treatment. This was taken as a criterion for complete skinning (Endo et ah, 1982). As in triton skinned fibers, tension development depends on the presence of ATP (Endo et ah, 1982). 

The fact that calmodulin diffuses out of triton skinned fibers could be used to demonstrate in recon-... 

The experiments on intact muscles, unlike those on skinned fibers, agree with the concept that relaxation of contracted smooth muscle is associated with LC20 dephosphorylation (Stull et al., 1991 Hartshorne and Kawamura, 1992 Somlyo and Somlyo, 1994). 

Hoar PE, Pato MD, Kerrick WG (1985) Myosin light chain phosphatase. Effect on the activation and relaxation of gizzard smooth muscle skinned fibers. J Biol Chem 260 8760-4876... 

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