2,5-Di-(tert-butyl)-1,4-benzohydroquinone and cyclopiazonic acid decrease the Ca2+ permeability of endoplasmic reticulum.
Specific inhibitors of the endoplasmic-reticulum Ca2+ pump will deplete intracellular stores and are therefore useful to study the role of store depletion on plasma-membrane Ca2+ permeability. We now report that the Ca(2+)-pump inhibitor 2,5-di-(tert-butyl)-1,4-benzohydroquinone (tBuBHQ) reduces the passive Ca2+ leak from the internal stores in permeabilized A7r5 vascular smooth-muscle cells. This aspecific effect occurred at concentrations that are normally used to empty the stores in intact cells. Cyclopiazonic acid exerted a similar, although less pronounced effect, while thapsigargin did not affect the passive Ca2+ leak. The inositol 1,4,5-trisphosphate-mediated Ca2+ release was not affected. tBuBHQ and cyclopiazonic acid cannot therefore be used as specific tools to probe the mechanism of receptor-mediated Ca2+ entry.
Missiaen
L
L
Laboratorium voor Fysiologie, K.U. Leuven Campus Gasthuisberg, Belgium.
De Smedt
H
H
Droogmans
G
G
Casteels
R
R
D016227:Benzoquinones / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000187:drug effects*; D002273:Carcinogens / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D016227:Benzoquinones; D002273:Carcinogens; D007211:Indoles; D013729:Terpenes; C067344:2,5-di-tert-butylbenzoquinone; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid