Exocytosis in neutrophils induced by thapsigargin and other inhibitors of calcium ATP-ase.
Inhibitors of the Ca(2+)-ATPase of intracellular calcium stores, such as thapsigargin, cyclopiazonic acid and 2,5-di-(t-butyl)-1,4-benzohydro-quinone, causes exocytosis in rabbit peritoneal neutrophils. In the absence of extracellular Ca2+ no exocytosis takes place. Fluoride, a non-specific inhibitor of Ca(2+)-ATPase, also causes exocytosis. It is known that all agents tested cause both a release of calcium from intracellular stores as well as an influx of extracellular calcium. The results indicate that induction of exocytosis is not due to a release of calcium from intracellular stores, but to the influx of extracellular calcium. Thapsigargin-induced exocytosis is not inhibited by L-type channel antagonists like verapamil, but is strongly inhibited by lanthanum ions, suggesting that the calcium required for induction of exocytosis is not entering via L-type channels, but via La(3+)-sensitive calcium channels.
Elferink
J G
JG
Department of Medical Biochemistry, University of Leiden, The Netherlands.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D005089:Exocytosis / Q000187:drug effects* / Q000502:physiology; D005966:Glucuronidase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007811:Lanthanum / Q000494:pharmacology; D009113:Muramidase / Q000378:metabolism; D009504:Neutrophils / Q000502:physiology*; D010529:Peritoneal Cavity / Q000166:cytology; D011817:Rabbits; D013729:Terpenes / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D019284:Thapsigargin
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D013729:Terpenes; D019284:Thapsigargin; D007811:Lanthanum; D007770:L-Lactate Dehydrogenase; D009113:Muramidase; D005966:Glucuronidase; D000252:Calcium-Transporting ATPases; D002118:Calcium