scholarly journals Effects of nicardipine on frog skeletal muscle in normal and calcium-free media.

1986 ◽  
Vol 36 (2) ◽  
pp. 339-348 ◽  
Author(s):  
Junna HATAE
Keyword(s):  
Skeletal Muscle ◽  
Frog Skeletal Muscle ◽  
Free Media

Restoration of the Ability of Frog Skeletal Muscle to Develop Potassium Contractures in Calcium-Deficient Media

1973 ◽  
Vol 51 (5) ◽  
pp. 335-343 ◽  
Author(s):  
J. G. Foulks ◽  
J. A. D. Miller ◽  
Florence A. Perry
Keyword(s):  
Skeletal Muscle ◽  
Contractile Function ◽  
Divalent Cations ◽  
Frog Skeletal Muscle ◽  
Free Media ◽  
Dependent Processes

A number of agents were tested for their ability to restore potassium (K) contractures in calcium-free media. Effective agents included caffeine, chloroform, more polar permeant anions (e.g. nitrate and perchlorate) in place of external chloride, as well as divalent cations, e.g. Mg2+. The presence of sufficient EGTA to preclude significant increases in [Ca]0 did not affect the extent of K contracture restoration produced by these agents. The loss of K contracture capacity in calcium-free media, and its restoration by effective agents, appear to be related to the disproportionate effect of these procedures on the relation between log [K]0 and the potential-dependent processes which regulate contractile function.

Subcontracture depolarizations increase sarcoplasmic ionized calcium in frog skeletal muscle

1985 ◽  
Vol 248 (5) ◽  
pp. C520-C526 ◽  
Author(s):  
K. W. Snowdowne
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Ionized Calcium ◽  
Frog Skeletal Muscle ◽  
Extracellular Concentration ◽  
Skeletal Muscle Fibers ◽  
Free Media

The hypothesis that the sarcoplasmic concentration of ionized calcium (Cai) of frog skeletal muscle may control its rate of metabolism was examined by monitoring the changes in Cai due to perturbations that are known, from the work of previous investigators, to alter the rate of metabolism. Cai was measured with aequorin, which was microinjected into isolated fibers in sufficient quantity to detect basal Cai. When these fibers were exposed to 5-18 mM KCl, 75 mM RbCl2, or 100 mM CsCl2, there was an increase in the aequorin signal. The potassium-evoked increase in the aequorin signal was diminished by an increase in the extracellular concentration of Ca or by Ca-free media containing 3.6 mM Mg, Mn, Sr, or Zn but was enhanced by subcontracture concentrations of caffeine or media containing nitrate instead of chloride. These results are consistent with the hypothesis that Cai may control the rate of metabolism in frog skeletal muscle fibers.

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

Electron Probe Analysis of Muscle

1982 ◽  
Vol 40 ◽  
pp. 398-401
Author(s):  
A. V. Somlyo ◽  
H. Shuman ◽  
A. P. Somlyo
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Resting State ◽  
Binding Sites ◽  
Electron Probe ◽  
Frog Skeletal Muscle ◽  
Electron Probe Analysis ◽  
Probe Analysis

Electron probe analysis of frozen dried cryosections of frog skeletal muscle, rabbit vascular smooth muscle and of isolated, hyperpermeab1 e rabbit cardiac myocytes has been used to determine the composition of the cytoplasm and organelles in the resting state as well as during contraction. The concentration of elements within the organelles reflects the permeabilities of the organelle membranes to the cytoplasmic ions as well as binding sites. The measurements of [Ca] in the sarcoplasmic reticulum (SR) and mitochondria at rest and during contraction, have direct bearing on their role as release and/or storage sites for Ca in situ.

Different actions of aconitine and veratrum alkaloids on frog skeletal muscle

1990 ◽  
Vol 21 (6) ◽  
pp. 863-868 ◽  
Author(s):  
Péter P. Nánási ◽  
Tamás Kiss ◽  
Miklós Dankó ◽  
David A. Lathrop
Keyword(s):  
Skeletal Muscle ◽  
Frog Skeletal Muscle ◽  
Veratrum Alkaloids
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