Contraction isometric

Katz, A., Sahlin, K., Henriksson, J. (1986b). Muscle ATP turnover rate during isometric contraction in humans. J. Appl. Physiol. 60, 1839-1842. 

Many activities require both types of muscle contraction. An example is running when one of the legs hits the ground, isometric contraction of the muscles within this limb keep it stiff and help to maintain body support. At the same time, isotonic contractions in the opposite leg move it forward to take the next stride. 

There is probably no biological phenomenon that has excited more interest among biochemists than the movement caused by the contractile fibers of muscles. Unlike the motion of bacterial flagella, the movement of muscle is directly dependent on the hydrolysis of ATP as its source of energy. Several types of muscle exist within our bodies. Striated (striped) skeletal muscles act under voluntary control. Closely related are the involuntary striated heart muscles, while smooth involuntary muscles constitute a third type. Further distinctions are made between fast-twitch and slow-twitch fibers. Fast-twitch fibers have short isometric contraction times, high maximal velocities for shortening, and high rates of ATP hydrolysis. 

Several groups have studied the effects on the muscle low-angle diffraction pattern of applying various mechanical perturbations to steady-state structures, either isometric contractions or rigor muscle at various strain levels. Huxley et al. (1981, 1983) used whole frog muscles and followed the effects of step changes of length of various amplitudes applied at the plateau of an otherwise isometric tetanus. They studied the effects on the M3 intensity as a whole. More recendy, with the two components of the active M3 resolved, Huxley et al. (2003) and Reconditi et al. (2003) have studied the separate behavior of these components. Huxley et al. (2003) found that the intensity ratio of the M30 to M3 varied from an initial value... 

Bordas, J., Diakun, G. P., Diaz, F. G., Harries, J. E., Lewis, R. A., Lowy, J., Mant, G. R., Martin- Fernandez, M. L., and Towns-Andrews, E. (1993). Two-dimensional time-resolved X-ray diffraction studies of live isometrically contracting frog sartorius muscle./. Muscle Res. Cell Motil. 14, 311-324. 

Harford, J. J., Chew, M. W., Squire, J. M., and Towns-Andrews, E. (1991). Crossbridge states in isometrically contracting fish muscle Evidence for swinging of myosin heads on actin. Adv. Biophys. 27, 45-61. 

Juanhuix, J., Bordas, J., Campmany, J., Svensson, A., Bassford, M. L., and Narayan, T. (2001). Axial disposition of myosin heads in isometrically-contracting muscles. Biophys.J. 80, 1429-1441. 

Kraft, T., Mattei, T., Radocaj, A., Piep, B., Nocula, C., Furch, M., and Brenner, B. (2002). Structural features of crossbridges in isometrically contracting skeletal muscle. Biophys.J. 82, 2536-2547. 

Mok, N. S., Knupp, C., and Squire, J. M. (2005). Ultrastructural changes during the development of isometric contraction in plaice fin muscle. 

Piazzesi, G., Reconditi, M., Dobbie, I., Linari, M., Boesecke, P., Diat, O., Irving, M., and Lombardi, V. (1999). Changes in conformation of myosin heads during the development of isometric contraction and rapid shortening in single frog muscle fibers. / Physiol. 514, 305-312. 

Brindle, K.M., Blackledge, M.J., Challiss, R.AJ., Radda, G.K. (1989). 31P NMR magnetization transfer measurements of ATP turnover during steady state isometric contraction in the rat hindlimb in vivo. Biochemistry 28,4887-4893. 

Kolodney MS, Wysolmerski RB. Isometric contraction by fibroblasts and endothelial cells in tissue culture A quantitative study. J Cell Biol. 1992 117 73-82. 

Isometric Contraction. One of the earliest observations of the thermal properties of epidermal protein was made by Rudall when he reported that cow snout epidermis contracted in water when heated (79). This thermally induced contraction was accompanied by a change in structure from alpha to cross-beta as exhibited in x-ray diffraction pat-... 

Figure 29. Isometric contraction of human stratum comeum A, chloroform-methanol extracted B, control (7)...

Baden, H., Cifford, A., Isometric Contraction of Epidermis and Stratum... 

Cohen I, GERRARD JM, White JG. ultrastructure of clots during isometric contraction. JCdl Biol 93 775-787,1982. 

A direct effect of AmB on cell function was suggested by in vitro experiments, which demonstrated a vasoconstrictor action of AmB in perfused afferent arterioles and isometrically contracting rings of rabbit aorta or renal artery, effects which were prevented in Ca -free medium and by Ca" " channel blockers or theophylline [103]. Thus, AmB-induced reductions in RBF or GFR are not secondary to activation of TGF, but due to its direct vasoconstrictor effect. A role for thromboxane A2 has also been suggested based upon partial inhibition of the AmB-induced vasoconstriction and reduction in GFR by pretreatment with ibuprofen or a thromboxane receptor antagonist [104]. 

Patients who have an inadequate response to /S-blockade may respond to verapamil." Doses of verapamil up to 480 mg/day have beneficial effects on symptoms. There are several reasons why CCBs may be of benefit to patients with HCM. Increased calcium concentrations have been shown to play a role in prolonging the ventricular action potential, as well as the duration of isometric contraction and relaxation. Patients with HCM have a hyperdynamic ventricle in systole and delayed relaxation and decreased compliance during diastole. CCBs decrease the myocardial oxygen demand, resulting in an improved balance between oxygen supply and demand therefore, diastolic function may be improved. 

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