Dantrolene Sodium: Effects on Crustacean Muscle

1974 ◽  
Vol 52 (4) ◽  
pp. 887-890 ◽  
Author(s):  
L. L. Odette ◽  
H. L. Atwood
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Neuromuscular Transmission ◽  
Contractile Response ◽  
Callinectes Sapidus ◽  
Muscle Membrane ◽  
Dantrolene Sodium ◽  
Muscle Contractile ◽  
Indirect Stimulation ◽  
Vertebrate Skeletal Muscle

The effect of dantrolene sodium, a muscle relaxant effective on vertebrate skeletal muscle, has been studied on the stretcher muscle of a crab (Callinectes sapidus). The drug rapidly and reversibly attenuates the muscle contractile response to direct and indirect stimulation. Neuromuscular transmission is unaffected, as are the electrical properties of the muscle membrane. It is concluded that dantrolene sodium uncouples excitation–contraction mechanisms in crustacean tonic muscle.

Association of increased pHi with calcium ion release in skeletal muscle

1978 ◽  
Vol 234 (3) ◽  
pp. C110-C114 ◽  
Author(s):  
R. J. Connett
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ion ◽  
Calcium Release ◽  
Muscle Membrane ◽  
Sartorius Muscle ◽  
Ion Release ◽  
Extracellular Medium ◽  
Dantrolene Sodium ◽  
External Potassium ◽  
Frog Sartorius

The pH difference across the cell membrane of frog sartorius muscle cells was measured with the distribution of 5,5-dimethyl-2,4-oxazolidine-dione (DMO) as the marker. Depolarization of the muscles to values at or below the contraction threshold caused by elevating external potassium up to approximately 20 mM resulted in an internal alkalinization. The change was smaller with superthreshold depolarization (20--30 mM [K+]). The alkalinization was blocked by agents that block calcium release from the sarcoplasmic reticulum (procaine and dantrolene sodium). Other agents that cause calcium release (caffeine, theophylline, and quinine) were found to give alkalinization when tested at concentrations just below the contracture threshold. Increased acidification of the extracellular medium was associated with the internal alkalinization. The data were interpreted as indicating the presence of a calcium-stimulated H+ and/or OH- ion transport system in the muscle membrane.

scholarly journals An analysis of the relationships between subthreshold electrical properties and excitability in skeletal muscle

2011 ◽  
Vol 138 (1) ◽  
pp. 73-93 ◽  
Author(s):  
Thomas H. Pedersen ◽  
Christopher L.-H. Huang ◽  
James A. Fraser
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Muscle Activity ◽  
Neuromuscular Transmission ◽  
Muscle Fibers ◽  
Low Frequency ◽  
Mammalian Muscle ◽  
Fast Twitch ◽  
T System

Skeletal muscle activation requires action potential (AP) initiation followed by its sarcolemmal propagation and tubular excitation to trigger Ca2+ release and contraction. Recent studies demonstrate that ion channels underlying the resting membrane conductance (GM) of fast-twitch mammalian muscle fibers are highly regulated during muscle activity. Thus, onset of activity reduces GM, whereas prolonged activity can markedly elevate GM. Although these observations implicate GM regulation in control of muscle excitability, classical theoretical studies in un-myelinated axons predict little influence of GM on membrane excitability. However, surface membrane morphologies differ markedly between un-myelinated axons and muscle fibers, predominantly because of the tubular (t)-system of muscle fibers. This study develops a linear circuit model of mammalian muscle fiber and uses this to assess the role of subthreshold electrical properties, including GM changes during muscle activity, for AP initiation, AP propagation, and t-system excitation. Experimental observations of frequency-dependent length constant and membrane-phase properties in fast-twitch rat fibers could only be replicated by models that included t-system luminal resistances. Having quantified these resistances, the resulting models showed enhanced conduction velocity of passive current flow also implicating elevated AP propagation velocity. Furthermore, the resistances filter passive currents such that higher frequency current components would determine sarcolemma AP conduction velocity, whereas lower frequency components excite t-system APs. Because GM modulation affects only the low-frequency membrane impedance, the GM changes in active muscle would predominantly affect neuromuscular transmission and low-frequency t-system excitation while exerting little influence on the high-frequency process of sarcolemmal AP propagation. This physiological role of GM regulation was increased by high Cl− permeability, as in muscle endplate regions, and by increased extracellular [K+], as observed in working muscle. Thus, reduced GM at the onset of exercise would enhance t-system excitation and neuromuscular transmission, whereas elevated GM after sustained activity would inhibit these processes and thereby accentuate muscle fatigue.

scholarly journals Temperature Effects on Membrane Chloride Conductance and Electrical Excitability of Lizard Skeletal Muscle Fibres

1989 ◽  
Vol 144 (1) ◽  
pp. 551-563 ◽  
Author(s):  
BRETT A. ADAMS
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Transmission ◽  
Threshold Current ◽  
Chloride Ions ◽  
Muscle Membrane ◽  
Muscle Fibres ◽  
Electrical Excitability ◽  
Ringer’S Solution ◽  
Single Nerve ◽  
Skeletal Muscle Fibres

1. Intracellular recording techniques were used to study the effects of temperature on resting membrane conductances, electrical excitability and synaptic efficacy in fast-glycolytic (FG) skeletal muscle fibres from the lizard Dipsosaurus dorsalis. 2. The conductance of the resting muscle membrane to chloride ions (gCl) increased from 488μS cm−2 at 15°C (pH7.8) to 730μS cm−2 at 45°C (pH7.4), yielding a temperature coefficient (thermal ratio, R10) of 1.14. Resting potassium conductance (gK) increased from 84μS cm−2 at 15°C to 236μScm−2 at 45 °C (R10=1.41). 3. Fibres bathed in Cl− -free Ringer's solution were hyperexcitable, and produced repetitive action potentials both during and following intracellular current injection. At the preferred body temperature of Dipsosaurus (near 40°C) the fibres also fired repetitively in response to single nerve shock. 4. The electrical excitability of Dipsosaurus fibres decreased with increasing temperature. Threshold current, measured at endplate regions of fibres bathed in normal Ringer's solution, was 146 nA at 15°C and 353 nA at 45°C (R10= 1.34). 5. Despite the temperature-dependent change in threshold current, at both 15 and 45°C all fibres examined had suprathreshold neuromuscular transmission response to single nerve shock. 6. The relative thermal independence of gCl in Dipsosaurus fibres may be an adaptation that contributes to a large safety factor for neuromuscular transmission at the high body temperatures preferred by this lizard species.

scholarly journals The molecular basis for sarcomere organization in vertebrate skeletal muscle

Cell ◽  
2021 ◽  
Vol 184 (8) ◽  
pp. 2135-2150.e13
Author(s):  
Zhexin Wang ◽  
Michael Grange ◽  
Thorsten Wagner ◽  
Ay Lin Kho ◽  
Mathias Gautel ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Basis ◽  
Vertebrate Skeletal Muscle
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