Inconstant Association of Aequorin Luminescence with Tension during Calcium Release in Skinned Muscle Fibres

IT is now generally accepted that the release of calcium ions from intracellular stores (presumably the sarcoplasmic reticulum (SR)) is a key step in excitation-contraction coupling in skeletal muscle1-4. One of the most useful preparations for studying the mechanism of release is the mechanically skinned muscle fibre preparation, originally devised by Natori5, and subsequently modified for use in aqueous solutions 6-9. The skinned fibre has the advantage that the cell membrane is removed, allowing free access of substances placed in the bathing medium to intracellular structures, but at the same time causing minimal disruption of these structures. The partially skinned (split) fibre has the further advantage that the patency of the T tubules is maintained13.