Inositol 1,4,5-trisphosphate enhances Ca2+-sensitivity of the contractile mechanism of chemically skinned rabbit skeletal muscle fibres.
The possibility that inositol 1,4,5-trisphosphate may also act on subcellular structures different from membraneous compartments has been examined using chemically skinned skeletal muscle fibres. At about 1 to 25 microM IP3 reversibly enhanced isometric steady-state force production of these preparations at free Ca2+ concentrations corresponding to submaximum activation in a concentration-dependent manner. The maximum Ca2+-induced tension was not altered by IP3. These results show that IP3 can modulate the apparent Ca2+-sensitivity of the contractile mechanism. They suggest a new modulatory function of IP3 in skeletal muscle.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D011817:Rabbits; D013048:Specimen Handling; D013403:Sugar Phosphates / Q000494:pharmacology*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium