Different actions of calcium channel blocking agents on resting membrane conductance in developing skeletal muscle

1981 ◽  
Vol 59 (4) ◽  
pp. 335-341 ◽  
Author(s):  
C. M. Thomson ◽  
W. F. Dryden
Keyword(s):  
Skeletal Muscle ◽  
Inhibitory Action ◽  
Membrane Conductance ◽  
Myoblast Fusion ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Calcium Channel Blocking Agents ◽  
Channel Blocking ◽  
Membrane Bound ◽  
Skeletal Muscle Fibres

The effects of Co2+, Mn2+, and La3+ (2 mM) and verapamil (5 × 10−6 M) on membrane conductance (Gm) and resting potential (Em) were studied in chick skeletal muscle fibres developing in culture. Cobalt and manganese had no effect on Gm at any time during myogenesis but verapamil caused a decrease in Gm in immature myotubes. This effect diminished with time and was absent by 3 days after myoblast fusion. Lanthanum caused an increase in Gm at all stages of development. All the agents studied caused a significant depolarization of Em. It is concluded that there is no resting calcium conductance in developing skeletal muscle but that there may be a resting sodium conductance which declines with maturation. Lanthanum may increase Gm by displacing membrane-bound calcium and destabilizing membrane structure. All the agents studied were thought to induce depolarization by an inhibitory action on (Na+ + K+)-ATPase.

CRAYFISH SKELETAL MUSCLE REQUIRES BOTH INFLUX OF EXTERNAL Ca2+ AND Ca2+ RELEASE FROM INTERNAL STORES FOR CONTRACTION

1993 ◽  
Vol 181 (1) ◽  
pp. 95-105 ◽  
Author(s):  
H. Ushio ◽  
S. Watabe ◽  
M. Iino
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Sarcoplasmic Reticulum ◽  
Procambarus Clarkii ◽  
Isometric Tension ◽  
Resting Potential ◽  
Muscle Fibres ◽  
Flexor Muscle ◽  
Caffeine Treatment ◽  
Skeletal Muscle Fibres

The isometric tension and membrane potential of single skeletal muscle fibres from the flexor muscle of the carpopodite in the meropodite of crayfish Procambarus clarkii (Girard) were studied to determine whether crayfish muscle contraction requires Ca2+ release from the sarcoplasmic reticulum. Contraction elicited by brief extracellular electrical stimulation was reduced by the removal of Ca2+ or by the addition of 25 micromolar nicardipine in crayfish Ringer's solution. Addition of 30 micromolar ryanodine with 1 mmol l-1 caffeine induced a transient contracture, the peak tension of which was 10–30 % of that of the high-K+ induced contracture and which declined to the pretreatment level in 20–60 min. After ryanodine-caffeine treatment, 30 mmol l-1 caffeine failed to induce contraction, suggesting that intracellular Ca2+ stores had been exhausted by the treatment. Extracellular electrical stimulation also failed to induce contraction after ryanodine-caffeine treatment, although the resting potential was not changed. These results suggest that Ca2+ release from the sarcoplasmic reticulum, together with Ca2+ influx via nicardipine-sensitive Ca2+ channels, is essential to the contraction of crayfish leg muscle fibres after a brief membrane depolarization.

scholarly journals The cAMP-binding Popdc proteins have a redundant function in the heart

2014 ◽  
Vol 42 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Thomas Brand ◽  
Subreena L. Simrick ◽  
Kar Lai Poon ◽  
Roland F.R. Schindler
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Myocytes ◽  
Structural Integrity ◽  
Effector Proteins ◽  
Pore Channel ◽  
Muscle Fibres ◽  
Interacting Protein ◽  
Membrane Bound ◽  
Skeletal Muscle Fibres ◽  
Camp Levels

Popdc (Popeye-domain-containing) genes encode membrane-bound proteins and are abundantly present in cardiac myocytes and in skeletal muscle fibres. Functional analysis of Popdc1 (Bves) and Popdc2 in mice and of popdc2 in zebrafish revealed an overlapping role for proper electrical conduction in the heart and maintaining structural integrity of skeletal muscle. Popdc proteins mediate cAMP signalling and modulate the biological activity of interacting proteins. The two-pore channel TREK-1 interacts with all three Popdc proteins. In Xenopus oocytes, the presence of Popdc proteins causes an enhanced membrane transport leading to an increase in TREK-1 current, which is blocked when cAMP levels are increased. Another important Popdc-interacting protein is caveolin 3, and the loss of Popdc1 affects caveolar size. Thus a family of membrane-bound cAMP-binding proteins has been identified, which modulate the subcellular localization of effector proteins involved in organizing signalling complexes and assuring proper membrane physiology of cardiac myocytes.

Interferon-gamma-like immunoreactivity and T-cell marker expression in rat skeletal muscle fibres

1989 ◽  
Vol 504 (2) ◽  
pp. 306-310 ◽  
Author(s):  
Inger Nennesmo ◽  
Tomas Olsson ◽  
Åke Ljungdahl ◽  
Krister Kristensson ◽  
Peter H. Van der Meide
Keyword(s):  
Skeletal Muscle ◽  
T Cell ◽  
Interferon Gamma ◽  
Muscle Fibres ◽  
Cell Marker ◽  
Rat Skeletal Muscle ◽  
Marker Expression ◽  
Skeletal Muscle Fibres
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