Role of calcium in thromboxane B2-mediated injury to rabbit gastric mucosal cells.
A sustained increase in cytosolic Ca2+ can damage gastric mucosal cells. The present study has examined the role of Ca2+ in thromboxane B2 (TXB2)-mediated damage of rabbit isolated gastric mucosal cells. Cells were isolated from rabbit oxyntic mucosa by collagenase-EDTA digestion. Cell metabolic activity and cell damage were estimated by alamar blue dye absorbance and trypan blue uptake, respectively. Cellular Ca2+ was monitored by indo-1 dye fluorescence. Addition of TXB2 (10(-6) and 10(-8) M) to the cell suspension resulted in a decrease in metabolic activity, and this effect was reduced when Ca2+ was removed from the incubation medium. TXB2 addition to the incubation medium resulted in an increase in cytosolic Ca2+ and incubation of cells with the intracellular Ca2+ chelator, BAPTA-AM (20 microM), reduced cell injury in response to TXB2. Incubation of cells with the Ca2+ ionophore A23187 (1-25 microM) resulted in a dose-dependent increase in trypan blue uptake and a reduction in cell metabolism. Cell injury in response to A23187 were exacerbated by addition of TXB2 (10(-8) M) to the cell suspension. TXB2 treatment reduced cellular content of reduced glutathione (GSH), while exogenous GSH addition (10 mM) reduced TXB2-mediated cell injury. These data demonstrate that TXB2 can directly injure gastric mucosal cells. Gastric mucosal cellular damage in response to TXB2 is mediated in part by a disruption of Ca2+ homeostasis as well as a reduction in cellular GSH content.
Wong
H M
HM
Department of Physiology, University of Western Ontario, London, Canada.
Soper
B D
BD
Tepperman
B L
BL
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D005753:Gastric Mucosa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D011817:Rabbits; D013929:Thromboxane B2 / Q000494:pharmacology*
D002614:Chelating Agents; D007476:Ionophores; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D000001:Calcimycin; D004533:Egtazic Acid; D013929:Thromboxane B2; D005978:Glutathione; D002118:Calcium