Inositol 1,4,5-trisphosphate-induced calcium release in permeabilized platelets is coupled to hydrolysis of inositol 1,4,5-trisphosphate to inositol 1,4-bisphosphate.
Metabolism of inositol 1,4,5-trisphosphate (IP3) and IP3-induced release of Ca2+ was analyzed in permeabilized human platelets. Both rapid Ca2+ release and hydrolysis of IP3 to inositol 1,4-bisphosphate (IP2) was observed after addition of IP3 to permeabilized, Ca(2+)-loaded platelets. In the absence of ATP or in the presence of inhibitors of the Ca(2+)-ATPase of the endoplasmic reticulum, no release of Ca2+ and little hydrolysis of IP3 occurs, indicating a coupling between the Ca2+ gradient across the membrane of the IP3-sensitive Ca2+ store and conversion of IP3 to IP2. In addition, the rapid recovery of the sensitivity of the IP3-sensitive Ca2+ store after successive additions of IP3 (increment detection) appears to be associated with hydrolysis of IP3.
Eberhard
M
M
Department of Research, Kantonsspital, Basel, Switzerland.
Erne
P
P
D000814:Aniline Compounds; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D002463:Cell Membrane Permeability; D005456:Fluorescent Dyes; D006801:Humans; D006868:Hydrolysis; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000097:blood* / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000097:blood* / Q000302:isolation & purification; D007700:Kinetics; D013050:Spectrometry, Fluorescence; D014966:Xanthenes
D000814:Aniline Compounds; D005456:Fluorescent Dyes; D007295:Inositol Phosphates; D014966:Xanthenes; C059715:Fluo-3; C044259:inositol 1,4-bis(phosphate); D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium