Heparin induces Ca2+ release from the terminal cysterns of skeletal muscle sarcoplasmic reticulum

Abstract
Using a Ca2+‐selective electrode and the chlorotetracycline fluorescence technique, the effects of heparin on Ca2+ transport in the sarcoplasmic reticulum (SR) of skeletal muscles in the absence of oxalate were investigated. It was shown that heparin (0.5–10 ) causes a rapid release of 40–50 nmol protein from the terminal cystern SR vesicles bound to 130–150 protein of Ca2+ in the presence of ATP. However, heparin has practically no effect on the longitudinal cystern fraction of SR. The effects of heparin can be prevented by ruthenium red. No influence of heparin is observed in the case of the Ca2+‐induced release of Ca2+ from the terminal cysterns. When the Ca2+ release is induced by heparin, no Ca2+‐induced release of Ca2+ takes place.