Action of TMB-8 (8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate) on cytoplasmic free calcium in adrenal glomerulosa cell.
To clarify the action of 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) on cellular calcium handling, changes in cytoplasmic free calcium concentration ([Ca2+]c) were studied in adrenal glomerulosa cell with a calcium-sensitive photoprotein, aequorin. Results of our previous study demonstrate that 100 microM TMB-8 almost completely blocks aldosterone response to angiotensin II (Biochem. J. 232 (1985) 87-92). At 50 or 100 microM, TMB-8 decreased basal [Ca2+]c significantly; however, these doses of TMB-8 had little effect on an angiotensin-induced increase in [Ca2+]c. When angiotensin-induced calcium release from an intracellular pool(s) was assessed by measuring changes in [Ca2+]c in the presence of 1 microM extracellular Ca2+, 100 microM TMB-8 had little inhibitory effect on angiotensin-induced calcium release. A higher dose of TMB-8 (250 microM) slightly inhibited calcium release. Additionally, TMB-8 did not affect exogenous arachidonic acid-induced calcium release. In contrast, 50 microM TMB-8 markedly inhibited 8 mM potassium-induced increase in [Ca2+]c. These results indicate that a major action of TMB-8 on cellular calcium is an inhibition of calcium influx but not of calcium release. We suggest that TMB-8 should not be used as an 'inhibitor of calcium release'.
D000311:Adrenal Glands; D000331:Aequorin; D000804:Angiotensin II / Q000494:pharmacology; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D011188:Potassium / Q000494:pharmacology
D001095:Arachidonic Acids; D000804:Angiotensin II; D016718:Arachidonic Acid; D000331:Aequorin; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D011188:Potassium; D002118:Calcium