A method for studying the depolarization-induced calcium ion release from fragmented sarcoplasmic reticulum

An optical method of studying the ‘depolarization’-induced Ca²⁺ release from isolated sarcoplasmic reticulum was presented. The method, which involves the use of metallochromic indicators, has the advantage of being able to perform the rapid kinetic measurement of the release. It was suggested that the velocity of the ‘depolarization’-induced Ca²⁺ release was rapid enough to account for the velocity of muscle contraction if the phenomenon is involved in the contraction mechanism. The change of membrane potential was also measured optically using a potential-sensitive dye. The possibility that this type of release is caused by osmotic effects is discussed.