Cyclopiazonic acid depletes intracellular Ca2+ stores and activates an influx pathway for divalent cations in HL-60 cells.
The filling state of intracellular Ca2+ stores has been proposed to regulate Ca2+ influx across the plasma membrane in a variety of tissues. To test this hypothesis, we have used three structurally unrelated inhibitors of the Ca(2+)-ATPase of intracellular Ca2+ stores and investigated their effect on Ca2+ homeostasis in HL-60 cells. Without increasing cellular inositol (1,4,5)trisphosphate levels, all three inhibitors (cyclopiazonic acid, thapsigargin, and 2,5-Di-tert-butylhydroquinone) released Ca2+ from intracellular stores, resulting in total depletion of agonist-sensitive Ca2+ stores. The Ca2+ release was relatively slow with a lag time of 5 s and a time to peak of 60 s. After a lag time of approximately 15 s, all three Ca(2+)-ATPase inhibitors activated a pathway for divalent cation influx across the plasma membrane. At a given concentration of an inhibitor, the plasma membrane permeability for divalent cations closely correlated with the extent of depletion of Ca2+ stores. The influx pathway activated by Ca(2+)-ATPase inhibitors conducted Ca2+, Mn2+, Co2+, Zn2+, and Ba2+ and was blocked, at similar concentrations, by La3+, Ni2+, Cd2+, as well as by the imidazole derivate SK&F 96365. The divalent cation influx in response to the chemotactic peptide fMLP had the same characteristics, suggesting a common pathway for Ca2+ entry. Our results support the idea that the filling state of intracellular Ca2+ stores regulates Ca2+ influx in HL-60 cells.
Demaurex
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Infectious Diseases Division, University Hospital, Geneva, Switzerland.
Lew
D P
DP
Krause
K H
KH
D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002413:Cations, Divalent / Q000378:metabolism; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D016257:Fura-2; D006873:Hydroquinones / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology*; D009183:Mycotoxins / Q000633:toxicity; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D002413:Cations, Divalent; D006873:Hydroquinones; D007093:Imidazoles; D007211:Indoles; D009183:Mycotoxins; D013729:Terpenes; C019359:2,5-di-tert-butylhydroquinone; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium; D016257:Fura-2; C000543:cyclopiazonic acid