[The contractile heart. Cellular and subcellular aspects].
The excitation-contraction coupling can be defined as the mechanisms involved when the action potential initiates a contraction response of the cardiac muscle cell. The action potential is conducted from cell to cell, resulting in a synchronized contraction of the myocardium. Both the propagation of the action potential and the myofibrillar contraction are dependent on changes in free Ca++ concentrations. Recently, the mediators and the molecular and structural components involved in the subcellular transforming of the action potential into a contraction have been characterized. The opening of voltage-dependent L-type Ca(++)-channels in the cell membrane stimulates a release of Ca++ from the sarcoplasmic reticulum. This Ca(++)-mediated Ca(++)-release appears to be a graded mechanism and is associated with the presence of structural couplings (Ca++ synapses) in the cardiac muscle cell.
Larsen
T H
TH
Institutt for anatomi og cellebiologi, Universitetet i Bergen.
D002118:Calcium / Q000378:metabolism / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology; D005455:Fluorescent Antibody Technique; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure
D015220:Calcium Channels; D002118:Calcium
Det kontraktile hjertet. Cellulaere og subcellulaere aspekter.