Involvement of ryanodine receptors in sphingosylphosphorylcholine-induced calcium release from brain microsomes.
Sphingosylphosphorylcholine (SPC) releases Ca2+ from brain microsomes. SPC-induced CA2+ release differs from IP3-induced Ca2+ release in that it is more extensive in the cerebrum than in the cerebellum. SPC has little effect on [3H] IP3 binding but enhances [3H] ryanodine binding, as expected for an activator of ryanodine receptors. SPC-induced Ca2+ release is inhibited by ryanodine receptor blockers but not by selective blockers of IP3 receptors. We conclude that SPC releases Ca2+ from brain microsomes by activating ryanodine receptors rather than IP3 receptors. Activation of an additional SPC-sensitive pathway for releasing Ca2+ is not precluded.
Dettbarn
C
C
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77555-0641.
Betto
R
R
Salviati
G
G
Sabbadini
R
R
Palade
P
P
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D002417:Cattle; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D009124:Muscle Proteins / Q000502:physiology*; D010171:Palmitoyl Coenzyme A / Q000494:pharmacology; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
D015220:Calcium Channels; D009124:Muscle Proteins; D000644:Quaternary Ammonium Compounds; D019837:Ryanodine Receptor Calcium Release Channel; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; D010171:Palmitoyl Coenzyme A; C027435:tetrapentylammonium; D013110:Sphingosine; D002118:Calcium