Inositol trisphosphate-induced calcium release in brain microsomes.
The effects of different ionic media on Ca2+ uptake and release in isolated brain microsomes were investigated. KCl (100 mM) provided the best medium for Ca2+ uptake in the presence of ATP. The effect of myo-inositol 1,4,5-trisphosphate (IP3) on Ca2+ release was examined and was maximum at 0.2 microM. IP3-induced Ca2+ release was dependent on extramicrosomal free Ca2+ concentration with maximal release at 5.0 microM free Ca2+. Replacement of KCl by sucrose or NaCl did not show any response to IP3. Electron microscopy showed that the microsomal fraction consisted of characteristic endoplasmic reticulum-derived vesicular profiles and were free of mitochondria or plasma membrane contamination. Our results support the concept that the endoplasmic reticulum is the target for IP-3 induced mobilization of Ca2+ in the cell.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002118:Calcium / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D008297:Male; D008854:Microscopy, Electron; D008861:Microsomes / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013403:Sugar Phosphates / Q000494:pharmacology*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium