Mechanical Transients
Mostrando 13-24 de 34 artigos, teses e dissertações.
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13. Influence of deuterium oxide on calcium transients and myofibrillar responses of frog skeletal muscle.
The influence of substituting D2O for H2O on calcium transients and on contraction was studied in intact single skeletal muscle fibres injected with aequorin and in mechanically skinned fibres from frogs. Most experiments were carried out at 10 degrees C. Experiments performed in vitro established that the calcium concentration-effect curve for aequorin is d
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14. Epinephrine enhances Ca2+ current-regulated Ca2+ release and Ca2+ reuptake in rat ventricular myocytes.
The voltage dependence of the intracellular Ca2+ transients was measured in single rat ventricular myocytes with the fluorescent Ca2+ indicator dye fura-2. The whole-cell voltage clamp technique was used to measure the membrane current, and 0.9 mM fura-2 was loaded into the cell by including it in the dialyzing solution of the patch electrode. A mechanical l
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15. Kinetics of contractile activation in voltage clamped frog skeletal muscle fibers.
Excitation-contraction coupling events leading to the onset of contraction were studied in single skeletal frog muscle fibers. This entailed the simultaneous measurement of the changes in intracellular calcium concentration using antipyrylazo III and fura-2, isometric force, and clamp voltage in a modified single vaseline gap chamber for the first time. The
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16. Intracellular calcium transients underlying the short-term force-interval relationship in ferret ventricular myocardium.
The influence of short-term changes in stimulation pattern, both on the strength of contraction and on the amplitude of intracellular free-Ca2+ transients, was investigated in ferret papillary muscles. Intracellular free-Ca2+ concentration ([Ca2+]) was assessed from the luminescence emitted from muscles microinjected with the Ca2+-sensitive photoprotein aequ
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17. Simultaneous electrical and optical measurements show that membrane fusion precedes secretory granule swelling during exocytosis of beige mouse mast cells.
Mast cells show dramatic morphological changes when undergoing exocytosis. We have investigated whether the first of those morphological changes, swelling of the secretory granule, precedes--and therefore possibly initiates--secretion or whether it occurs after fusion of the granule and plasma membranes. We used cell membrane capacitance to detect the moment
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18. Regulation of Actin Tension in Plant Cells by Kinases and Phosphatases1
Changes in the organization and mechanical properties of the actin network within plant and animal cells are primary responses to cell signaling. These changes are suggested to be mediated through the regulation of G/F-actin equilibria, alterations in the amount and/or type of actin-binding proteins, the binding of myosin to F-actin, and the formation of myo
American Society of Plant Physiologists.
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19. Force responses following stepwise length changes of rat skeletal muscle fibre types.
1. Force responses following stepwise length changes of Ca(2+)-activated skinned leg muscle fibres (6 degrees C) of the rat were correlated with their myosin heavy chain (HC) isoforms (myosin HC I, fibre type I; myosin HC IIA, type IIA; myosin HC IID (HC IIX), type IID (type IIX); myosin HC IIB, type IIB) in order to study the mechanical properties of these
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20. Relaxation of rabbit psoas muscle fibres from rigor by photochemical generation of adenosine-5'-triphosphate.
Correlations have been made between the mechanical and biochemical descriptions of muscle relaxation. Skinned muscle fibres in the rigor state were incubated in a solution containing P3-1-(2-nitro)phenylethyladenosine-5'-triphosphate, 'caged ATP', an inert photolabile precursor of ATP, and free Ca2+ concentration less than 10(-8) M. The mechanical response o
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21. GAP43 stimulates inositol trisphosphate-mediated calcium release in response to hypotonicity
The identification of osmo/mechanosensory proteins in mammalian sensory neurons is still elusive. We have used an expression cloning approach to screen a human dorsal root ganglion cDNA library to look for proteins that respond to hypotonicity by raising the intracellular Ca2+ concentration ([Ca2+]i). We report the unexpected identification of GAP43 (also kn
Oxford University Press.
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22. The differential effects of twitch potentiators on charge movements in frog skeletal muscle.
The effects of twitch potentiators at physiologically effective concentrations on intramembrane charge movements were examined in voltage-clamped frog skeletal muscle in the presence and absence of tetracaine. Caffeine, even at high concentrations (2.5 mM) did not alter the potential dependence of either tetracaine-sensitive or tetracaine-resistant portions
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23. Alterations in intracellular calcium and tension of activated ferret papillary muscle in response to step length changes.
1. To study the effects of mechanical constraints on the calcium (Ca2+) affinity of cardiac troponin C, we analysed the tension and aequorin light (AL, intracellular Ca2+) transients in response to a step length change in aequorin-injected ferret right ventricular papillary muscles. The muscle preparations were continuously activated with ouabain (10(-4) M)
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24. Millisecond time-resolved changes in x-ray reflections from contracting muscle during rapid mechanical transients, recorded using synchrotron radiation.
Low-angle x-ray diffraction diagrams have been recorded from frog sartorius muscles by using synchrotron radiation as a high-intensity x-ray source. This has enabled changes in some of the principal reflections of interest to be followed with a time resolution of 1 ms, during small but very rapid length changes imposed on a contracting muscle. The 143-A meri