Properties of muscle

This theory was also able to explain the energetic properties of muscle. Hill had found in 1938 that the heat produced by a muscle was proportional to the shortening distance and Huxley was able to derive this relationship from his mathematical expressions. However, Hill found later (Hill, 1964), that the rate of energy output did not increase at a constant rate as the velocity increased, as he had originally found, but declined at high velocities. This could not be explained by Huxley s 1957 theory. 

It is necessary to discuss another chemical feature related to water-soluble polymers cross-cross-linking — the component that separates viscous systems from gel systems. Viscous systems flow, and it follows, therefore, that they do not possess the tensile properties of muscles. High-viscosity systems have structural integrity, gels provide the necessary combination of tensile strength and elongation or stretch. 

Jaurequi, C.A., Regenstein, J.M., and Baker, R.C. 1981. A simple centrifugal method for measuring expressible moisture A water-binding property of muscle foods. J. Food Sci. 46 1271 -1273. 

Blair, K.L. and Anderson, P.A.V. (1994) Physiological and pharmacological properties of muscle cells isolated from the flatworm Bdelloura Candida (triclada). Parasitology 109, 325-335. 

Figure 2. Dielectric properties of muscle in the impedance plane, with reactance X plotted against resistance R and the impedance Z==R + jXflj. The large circle results from the (3-dispersion and the small one from the a-dispersion. The plot does not include the y-dispersion.

Kawai, Y., Hirayama, H., and Hatano, M., Emulsifying ability and physicochemical properties of muscle proteins of fall chum salmon Oncorhynchus keta during spawning migration, Nippon Suisan Gakkaishi, 56, 625, 1990. 

Guderley, H. Hochachka, P.W. Catalytic and regulatory properties of muscle pyruvate kinase from Cancer magister. J. Exp. Zook, 212, 461-469 (1980)... 

Saunders, D.K. Klemm, R.D. (1994). Seasonal changes in the metabolic properties of muscle in blue-winged teal Anas discors. Comp. Biochem. Physiol., 107A, 63-8. 

FIGURE 48.3 The Hill model of muscle separates the artive properties of muscle into a contractile element, in series with a purely elastic element. The properties of the passive muscle are represented by the parallel elastic element. 

For chemically driven motors the asymmetric well with depth F is a trompe I oeil that fools the reader into concluding that the directionality of motion and other thermodynamic aspects of muscle behavior are governed by the spring and its anharmonicity. As is shown using the principle of microscopic reversibility, this is not the case. In fact, the intrinsic (zero load) direction of motion, and every thermodynamic property of muscle behavior, is governed solely by the activation barrier differences A (a) and A5 (0) that determine the chemical specificities, and not by the energy difference (/a( ) — Ua 0) that drives the power stroke. 

In the discussion below, the force-length and force-velocity properties of muscle are assumed to be scaled-up versions of the properties of muscle fibers, which in turn are assumed to be scaled-up versions of properties of sarcomeres. 

Modeling Contraction Dynamics. A. F. Huxley developed a mechanistic model to explain the structural changes at the sarcomere level that were seen under the electron microscope in the late 1940s and early 1950s. Because of its complexity, however, this (cross-bridge) model is rarely, if ever, used in studies of coordination. Instead, an empirical model, proposed by A. V. Hill, is used in virtually all models of movement to account for the force-length and force-velocity properties of muscle (Hill, 1938) (Fig. 6.21). 

A concise description of the active properties of muscle tissue, with direct application to the development of forces within the human gait cycle. 

Overall, from the kinetic properties of muscle adenylosuccinate synthetase reported here, it would appear that the most important regulatory factor in muscle is the availability of IMP. A positive correlation between IMP concentration and adenylosuccinate production in muscle has already been demonstrated (58). The decrease in phosphocreatine during contraction would also lead to an increase in activity. However, hydrolysis of phosphocreatine will produce a concomitant increase in the concentration of inorganic phosphate, which is as good an inhibitor of adenylosuccinate synthetase as phosphocreatine (28). The changes in GDP and fructose 1,6-bisphosphate would appear to oppose this process. Whether these two metabolites serve to dampen the oscillations of the purine nucleotide cycle in vivo is unclear. It has recently been demonstrated that muscle tissue has a significant capacity for de novo purine biosynthesis 104). This requires that the basic... 

Other studies included the investigation of the stabilizing effect of sorbitol on hen egg white lysozyme and the use of the self-diffusion coefficient, D, to follow the solution and aggregative properties of lysozyme at different pH, temperature, and protein and salt concentrations. The properties of frozen ovalbumin solutions were studied by NMR relaxation spectroscopy. It is known that the functional properties of muscle proteins are affected by protein interactions with ions, and NMR was used to assess protein/water, protein/salt, and protein/protein interactions in myofibrillar protein solutions. Previous X-ray and NMR studies on collagen and peptides were reviewed by Mayo and, more recently, such types of system were characterized by high-resolution H and C NMR. °0 The structure, hydration state, and nature of the interactions between water and gelatin were determined by time domain NMR. ... 

Calcium is the most abundant mineral element in the animal body. It is an important constituent of the skeleton and teeth, in which about 99 per cent of the total body calcium is found in addition, it is an essential constituent of Uving cells and tissue fluids. Calcium is essential for the activity of a number of enzyme systems, including those necessary for the transmission of nerve impulses and for the contractile properties of muscle. It is also concerned in the coagulation of blood. In blood, the element occurs in the plasma the plasma of mammals usually contains 80-120 mg calcium/1, but that of laying hens contains more (300-400 mg/1). 

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