title: Quantal release of calcium in permeabilized A7r5 cells is not caused by intrinsic inactivation of the inositol trisphosphate receptor.
abstract: Since the role of intrinsic inactivation of the receptor for inositol 1,4,5-trisphosphate (InsP3) in the phenomenon of quantal release of Ca2+ is still a point of debate, we investigated whether inactivation of the InsP3 receptor can be responsible for quantal release in permeabilized A7r5 cells. A crucial experiment was that a second challenge of the cells with a low dose of InsP3, after washing out the first challenge, was unable to produce a renewed phasic response under conditions where the Ca2+ pumps were blocked. A new phasic response was however obtained with either addition of a higher dose of InsP3 or after allowing the refilling of the Ca2+ stores. We conclude therefore that quantal Ca2+ release in A7r5 cells is not due to InsP3 receptor inactivation.
authors.affiliation: Laboratorium voor Fysiologie, K.U.Leuven Campus Gasthuisberg O/N, Belgium.
authors.forename: J B
authors.initials: JB
authors.lastname: Parys
authors.forename: L
authors.initials: L
authors.lastname: Missiaen
authors.forename: H
authors.initials: H
authors.lastname: De Smedt
authors.forename: I
authors.initials: I
authors.lastname: Sienaert
authors.forename: R H
authors.initials: RH
authors.lastname: Henning
authors.forename: R
authors.initials: R
authors.lastname: Casteels
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D015220:Calcium Channels / Q000378:metabolism*; D002451:Cell Compartmentation / Q000187:drug effects; D002460:Cell Line; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009130:Muscle, Smooth / Q000502:physiology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D013729:Terpenes; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium