Inhibition by ouabain of palytoxin-induced catecholamine secretion and calcium influx into cultured bovine adrenal chromaffin cells.
The effect of ouabain on palytoxin (PTX)-induced catecholamine secretion from cultured bovine adrenal chromaffin cells was examined in relation to its effect on calcium (Ca2+) influx into the cells. Ouabain showed concentration-dependent inhibition of catecholamine secretion induced by PTX. Ouabain also inhibited [45Ca]2+ influx induced by PTX, this inhibition being parallel with that of catecholamine secretion. The inhibitory effects of ouabain on PTX-induced catecholamine secretion and [45Ca]2+ influx were both overcome by increasing the concentrations of PTX, indicating that ouabain inhibited the actions of PTX in a competitive manner. These results suggest that the ouabain-sensitive (or-binding) site on the cell membrane might be the target site of action of PTX, which causes an increase in Ca2+ permeability and initiation of catecholamine secretion.
Yoshizumi
M
M
Department of Pharmacology, Tokushima University School of Medicine, Japan.
Ishimura
Y
Y
Masuda
Y
Y
Houchi
H
H
Kato
I
I
Oka
M
M
D000178:Acrylamides; D000311:Adrenal Glands / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002837:Chromaffin Granules; D003064:Cnidarian Venoms / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D000095702:Polyether Toxins
D000178:Acrylamides; D002118:Calcium; D002395:Catecholamines; D003064:Cnidarian Venoms; D010042:Ouabain; D011188:Potassium; D000254:Sodium-Potassium-Exchanging ATPase; C010272:palytoxin; D000095702:Polyether Toxins