Mechanical response of the mammalian myocardium to modifications of the action potential

1971 ◽  
Vol 5 (supp1) ◽  
pp. 64-70 ◽  
Author(s):  
R. L. Kaufmann ◽  
H. Antoni ◽  
R. Hennekes ◽  
R. Jacob ◽  
M. Kohlhardt ◽  
...  
Keyword(s):  
Action Potential ◽  
Mechanical Response ◽  
Mammalian Myocardium

Action potential of amphibian single auricular muscle fiber: a dual response

1961 ◽  
Vol 201 (6) ◽  
pp. 1101-1108 ◽  
Author(s):  
Ernest B. Wright ◽  
M. Ogata
Keyword(s):  
Action Potential ◽  
Mechanical Response ◽  
Vagal Stimulation ◽  
Slow Inactivation ◽  
Plateau Phase ◽  
Low Oxygen ◽  
Dual Response ◽  
Carrier Systems ◽  
Prolonged Response ◽  
Slow System

The intracellular recording of a single auricle fiber of frog or toad shows a spike-dip-plateau contour, suggesting two depolarizations are involved and two deflections comprise the action potential contour. Low oxygen reduces the plateau phase. Acetylcholine applied locally by microejection (or by vagal stimulation) acts specifically to cause plateau phase to be diminished or abolished and simultaneously affects the mechanical response in a like manner. The Q10 of the spike exposed alone by the acetylcholine effect is significantly different (1.2) from the Q10 value of the normal prolonged response (2.4) or the mechanogram (2.5). The evidence supports the idea that two ion carrier systems exist in the excitable membrane: one which reacts rapidly, the other more slowly. In cardiac muscle the fast one causes the spike depolarization, which itself is adequate to trigger the slow response. The slow system must react not specifically with potassium but with sodium also and causes the prolonged depolarization or plateau. Recovery is probably due to slow inactivation of this second process.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

How to sample the entire length of a single muscle fiber quick-frozen after electrical point stimulation for high resolution EM

1992 ◽  
Vol 50 (1) ◽  
pp. 776-777
Author(s):  
Joachim R. Sommer ◽  
Teresa High ◽  
Betty Scherer ◽  
Isaiah Taylor ◽  
Rashid Nassar
Keyword(s):  
Skeletal Muscle ◽  
High Resolution ◽  
Action Potential ◽  
Muscle Fiber ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Electrical Field Stimulation ◽  
Skeletal Muscle Fiber ◽  
Freeze Dried ◽  
Quick Freezing

We have developed a model that allows the quick-freezing at known time intervals following electrical field stimulation of a single, intact frog skeletal muscle fiber isolated by sharp dissection. The preparation is used for studying high resolution morphology by freeze-substitution and freeze-fracture and for electron probe x-ray microanlysis of sudden calcium displacement from intracellular stores in freeze-dried cryosections, all in the same fiber. We now show the feasibility and instrumentation of new methodology for stimulating a single, intact skeletal muscle fiber at a point resulting in the propagation of an action potential, followed by quick-freezing with sub-millisecond temporal resolution after electrical stimulation, followed by multiple sampling of the frozen muscle fiber for freeze-substitution, freeze-fracture (not shown) and cryosectionmg. This model, at once serving as its own control and obviating consideration of variances between different fibers, frogs etc., is useful to investigate structural and topochemical alterations occurring in the wake of an action potential.

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