Title: Skeletal muscle physiology | BJA Education | Oxford Academic
Headings: Skeletal muscle physiology
Skeletal muscle physiology
Published:
Subject
Issue Section:
Key points
Electrical events in muscle contraction
Excitation-contraction coupling
Contractile structures
Force transmission
Determinants of force of contraction
Summation
Recruitment
Energy for contraction
Muscle fibre-types
Further reading

Content: We now know that, although the t-tubular dihydropyridine receptors show marked amino acid homology with L-type voltage gated Ca 2+ channels of other tissues, they do not function as Ca 2+ channels. Their role in skeletal muscle is that of voltage sensors. When the action potential arrives in the t-tubule, the change in membrane potential leads to a conformational change in the α-subunit of the dihydropyridine receptor. This subunit consists of four transmembrane domains each of six segments ( Fig. 1 ). The first and sixth segments of adjacent domains are linked by alternating extracellular and cytoplasmic loops of amino acids. The voltage-induced conformational change results in the projection of the cytoplasmic loop between