Electromechanical coupling

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As electromechanical coupling refers to the relationship between the action potential of a muscle cell and its subsequent contraction . The action potential is an electrical impulse, the contraction the mechanical response to it, hence the term “electromechanical coupling”. The coupling between the electrical stimulus and the mechanical response occurs through calcium ions, which are released into the cytosol from the sarcoplasmic reticulum of a sarcomere . They bind to troponin C , which then changes its conformation in such a way that the binding site between actin and myosin is exposed. In skeletal muscles, the L-type calcium channels (1,4-dihydropyridine receptors) are fundamentally involved in the phenomenon of the excitation-contraction coupling (the transfer of electrical excitation after a nerve impulse) to the release of calcium and activation of the contraction. The CaV1.1 subunits "mechanically" transmit the electrical signal to ryanodine receptors without calcium flowing through the skeletal muscle channels. This explains why blockers of the L-type calcium channels ( calcium antagonists ) have no effects (side effects) on the contraction of the mammalian skeletal muscle, in contrast to the heart muscle or the smooth vascular muscles.

The electromechanical coupling plays especially in the clinical picture electromechanical dissociation (EMD of Engl. Electro mechanical dissociation ) a decisive role. The electrical activity of the myocardium can be observed via an EKG , but due to the disturbed transmission there is no contraction and therefore no pumping power. This condition rarely occurs during resuscitation and can not be remedied with defibrillation . It is also known as Pulusless Electrical Activity (PEA) because of the symptoms observed .

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Individual evidence

  1. ^ RA Bannister, KG Beam: Ca (V) 1.1: The atypical prototypical voltage-gated Ca²⁺ channel. In: Biochim Biophys Acta. Volume 1828, No. 7, Jul 2013, pp. 1587–1597. doi: 10.1016 / j.bbamem.2012.09.007 . Epub 2012 Sep 13.