Potent excitatory effect of maitotoxin on Ca channels in the insect skeletal muscle

1984 ◽  
Vol 400 (4) ◽  
pp. 439-441 ◽  
Author(s):  
T. Miyamoto ◽  
Y. Ohizumi ◽  
H. Washio ◽  
Y. Yasumoto
Keyword(s):  
Skeletal Muscle ◽  
Ca Channels ◽  
Excitatory Effect ◽  
Insect Skeletal Muscle

scholarly journals Internal and external effects of dihydropyridines in the calcium channel of skeletal muscle.

1990 ◽  
Vol 95 (1) ◽  
pp. 1-27 ◽  
Author(s):  
H H Valdivia ◽  
R Coronado
Keyword(s):  
Skeletal Muscle ◽  
Lipid Bilayers ◽  
Radioligand Binding ◽  
Quantitative Agreement ◽  
Bay K 8644 ◽  
Single Channels ◽  
Ca Channel ◽  
Ca Channels ◽  
Receptor Sites ◽  
Internal Side

The agonist effect of the dihydropyridine (DHP) (-)Bay K 8644 and the inhibitory effects of nine antagonist DHPs were studied at a constant membrane potential of 0 mV in Ca channels of skeletal muscle transverse tubules incorporated into planar lipid bilayers. Four phenylalkylamines (verapamil, D600, D575, and D890) and d-cis-diltiazem were also tested. In Ca channels activated by 1 microM Bay K 8644, the antagonists nifedipine, nitrendipine, PN200-110, nimodipine, and pure enantiomer antagonists (+)nimodipine, (-)nimodipine, (+)Bay K 8644, inhibited activity in the concentration range of 10 nM to 10 microM. Effective doses (ED50) were 2 to 10 times higher when HDPs were added to the internal side than when added to the external side. This sidedness arises from different structure-activity relationships for DHPs on both sides of the Ca channel since the ranking potency of DHPs is PN200-110 greater than (-)nimodipine greater than nifedipine approximately S207-180 on the external side while PN200-110 greater than S207-180 greater than nifedipine approximately (-)nimodipine on the internal side. A comparison of ED50's for inhibition of single channels by DHPs added to the external side and ED50's for displacement of [3H]PN200-110 bound to the DHP receptor, revealed a good quantitative agreement. However, internal ED50's of channels were consistently higher than radioligand binding affinities by up to two orders of magnitude. Evidently, Ca channels of skeletal muscle are functionally coupled to two DHP receptor sites on opposite sides of the membrane.

NEUROTROPHIC INFLUENCES IN INSECT SKELETAL MUSCLE

Abstracts ◽  
1978 ◽  
pp. 643
Author(s):  
R.B. Clark ◽  
K.A.F. Gration ◽  
P.N.R. Usherwood
Keyword(s):  
Skeletal Muscle ◽  
Insect Skeletal Muscle

A transmission delay and the effect of temperature at the triadic junction of skeletal muscle

1986 ◽  
Vol 229 (1254) ◽  
pp. 97-110 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Effect Of Temperature ◽  
Muscle Fibres ◽  
Time Interval ◽  
Strong Temperature Dependence ◽  
Ca Channels ◽  
T Tubules ◽  
Skeletal Muscle Fibres ◽  
Terminal Cisternae

The coupling process at the triadic junctions in skeletal muscle fibres is characterized by a significant latency between the depolarization of the transverse tubular membrane and the release of Ca from the sarcoplasmic reticulum. This time interval, the triadic delay, is sufficiently long to allow for the participation of a chemical process. The strong temperature dependence of the triadic delay ( Q 10 near 2.7) suggests that a sequence of chemical steps may link the electical signal in the T-tubules to the opening of Ca channels in the terminal cisternae of the sarcoplasmic reticulum.

scholarly journals THE FINE STRUCTURE OF STRIATED MUSCLE

1956 ◽  
Vol 2 (4) ◽  
pp. 131-142 ◽  
Author(s):  
A. J. Hodge
Keyword(s):  
Skeletal Muscle ◽  
Phase Contrast ◽  
Striated Muscle ◽  
General Structure ◽  
Electron Microscopic ◽  
Strong Contraction ◽  
Other Substances ◽  
Microscopic Studies ◽  
Insect Skeletal Muscle ◽  
Band Material

The available evidence from phase contrast, polarization optical, and electron microscopic studies on vertebrate skeletal muscle, insect skeletal muscle, and dipteran flight muscle is interpreted as favoring the following general structure of striated muscle. A continuous array of filaments (actin) runs through all bands of the sarcomere. These are linked by an axially periodic system of transverse filamentous bridges. Myosin (and probably other substances) are localized in the A bands. The system of transverse bridges compensates the birefringence of actin and is thus responsible for the isotropy of the I band. Myosin is responsible for the birefringence of the A bands. On strong contraction, A band material migrates to the Z bands to form contraction bands. It is not yet certain whether this migration involves myosin or another A band component.

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