scholarly journals Length dependence of force generation exhibit similarities between rat cardiac myocytes and skeletal muscle fibres

2010 ◽  
Vol 588 (15) ◽  
pp. 2891-2903 ◽  
Author(s):  
Laurin M. Hanft ◽  
Kerry S. McDonald
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Myocytes ◽  
Force Generation ◽  
Muscle Fibres ◽  
Length Dependence ◽  
Skeletal Muscle Fibres ◽  
Rat Cardiac Myocytes

scholarly journals Sarcomere-length dependence of myosin filament structure in skeletal muscle fibres of the frog

2014 ◽  
Vol 592 (5) ◽  
pp. 1119-1137 ◽  
Author(s):  
Massimo Reconditi ◽  
Elisabetta Brunello ◽  
Luca Fusi ◽  
Marco Linari ◽  
Manuel Fernandez Martinez ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcomere Length ◽  
Myosin Filament ◽  
Muscle Fibres ◽  
Length Dependence ◽  
Filament Structure ◽  
Skeletal Muscle Fibres

Excitation—contraction coupling in skeletal and caudal heart muscle of the hagfishEptatretus burgeriGirard

2002 ◽  
Vol 205 (22) ◽  
pp. 3535-3541
Author(s):  
Isao Inoue ◽  
Izuo Tsutsui ◽  
Quentin Bone
Keyword(s):  
Skeletal Muscle ◽  
Heart Muscle ◽  
Force Generation ◽  
Muscle Fibres ◽  
Fast Skeletal Muscle ◽  
K Concentration ◽  
Electrical Stimuli ◽  
Skeletal Muscle Fibres ◽  
Coupling Mechanisms ◽  
External K

SUMMARYHagfishes are regarded as the most primitive living craniates. Excitation—contraction (E—C) coupling mechanisms were studied in skeletal and caudal heart muscle fibres of the hagfish Eptatretus burgeri. In white (fast) skeletal muscle fibres from the musculus tubulatus, force generation in response to electrical stimulation was maintained in nominally Ca2+ free artificial seawater (ASW)(0Ca2+-ASW) containing 10 mmol l-1 Co2+ (a blocker of Ca2+ currents). Similarly, in red (slow) fibres from parietal muscle bathed in 0Ca2+-ASW containing 10 mmol l-1 Co2+, force generation occurred in association with K+ depolarisation when the external K+ concentration was increased to 100 mmol l-1. Therefore, external Ca2+ is not required for muscle contraction. Hence, both white and red fibres possess the function of depolarisation-induced Ca2+-release from intracellular Ca2+ stores. This function is the same as in the skeletal muscle of all other vertebrates. In caudal heart muscle fibres,twitches in response to electrical stimuli were maintained in 0Ca2+-ASW containing 30 mmol l-1 Co2+. In fibres loaded with fluo-3 bathed in 0Ca2+-ASW containing 30 mmol l-1 Co2+, an increase in the intracellular free Ca2+ level associated with K+ depolarisation was observed after the external K+ concentration was increased to 100 mmol l-1. Thus E—C coupling in the caudal heart muscle is also of the vertebrate skeletal muscle type.

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.

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