Failure of inositol 1,4,5-trisphosphate to elicit or potentiate Ca2+ release from isolated skeletal muscle sarcoplasmic reticulum.

This study was conducted to resolve the conflicting reports regarding the ability of inositol 1,4,5-trisphosphate (IP3) to elicit the release of Ca2+ from isolated sarcoplasmic reticulum derived from skeletal muscle. Three different conditions were employed, one of which has been reported to produce an IP3 induced release of Ca2+. Sarcoplasmic reticulum vesicles with and without intact feet structures failed to respond to added IP3. In addition, IP3 had no effect on the Ca2+-induced release of Ca2+. These results suggest that, unlike other tissue, IP3 does not mobilize the release of Ca2+ from skeletal muscle sarcoplasmic reticulum. IP3 is therefore unlikely to be the physiological signal linking transverse-tubule depolarization with Ca2+ release from the sarcoplasmic reticulum.