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

scholarly journals Electrophysiological comparison of insecticide and alkaloid agonists of Na channels.

1987 ◽  
Vol 90 (1) ◽  
pp. 75-93 ◽  
Author(s):  
M D Leibowitz ◽  
J R Schwarz ◽  
G Holan ◽  
B Hille
Keyword(s):  
Skeletal Muscle ◽  
Dependent Manner ◽  
Na Channels ◽  
Frog Skeletal Muscle ◽  
Na Current ◽  
Ionic Selectivity ◽  
Bathing Medium ◽  
Veratrum Alkaloids ◽  
Activation Gating ◽  
Dependent Modification

Macroscopic currents in Na channels were recorded from adult frog skeletal muscle under voltage clamp as various toxins were added to the bathing medium. Veratridine, cevadine, and 3-(4-ethoxybenzoyl)-veracevine modified the Na channels in a use-dependent manner during depolarizations and held them open for 3, 2.4, and 1.2 s, respectively, at -90 mV. The three alkaloids modified channels in the same way. Activation gating was shifted about -100 mV by the modification, and reversible closing of the channels by strong hyperpolarizations slowed reversal of the modification. The synthetic insecticides deltamethrin, EDO, GH739, and GH414 also modified channels during depolarizations that opened channels. The modification lasted 3 s with deltamethrin, but only 3-5 ms with the others. Hyperpolarization speeded the shutting off of current in insecticide-modified channels, but no reversible activation gating could be demonstrated. The ionic selectivity, PNa/PNH4, of channels was decreased by all of the toxins. This ratio was 0.11 in normal channels, 0.26 in insecticide-modified channels, and 0.7-1.6 in veratrum-alkaloid-modified channels. During use-dependent modification, the veratrum alkaloids reduced the total Na current markedly, while deltamethrin did not. Thus, alkaloid and insecticide modifications share many features but differ in how much the conducting properties of the pore are changed and whether the channel can close reversibly while the toxin remains bound.

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.

scholarly journals Permeability of Frog Skeletal Muscle Cells to Choline

1961 ◽  
Vol 44 (6) ◽  
pp. 1159-1164 ◽  
Author(s):  
Eugene M. Renkin
Keyword(s):  
Skeletal Muscle ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Frog Skeletal Muscle

Using choline-methyl-C14 as a tracer, it has been shown that choline+ penetrates into the cells of resting frog skeletal muscle at a rate similar to that of Na+, and that it escapes from these cells much more slowly than does Na+. Some implications of these findings are discussed.

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