The effect of the prostaglandin derivative PGBx on calcium uptake and release by skeletal muscle sarcoplasmic reticulum.

The effects of the prostaglandin derivative PGBx on calcium release and uptake by skeletal muscle sarcoplasmic reticulum (SR) and on (Ca2+ + Mg2+)- adenosine triphosphatase (ATPase) activity were studied using skeletal muscle from rabbit hind legs. Both calcium uptake and Ca2+-ATPase activity were significantly inhibited by PGBx. Addition of PGBx to SR vesicles resulted in the release of calcium. It is proposed that this action of PGBx could be effected by the inhibition of ATPase and resulting passive release of calcium. The possibility also exists that PGBx could decrease the capacity of the SR vesicles for calcium in addition to any possible ionophoretic properties.