Effects of 5,8,11,14-eicosatetraynoic acid on thapsigargin-induced calcium entry, and intracellular pH in thyroid FRTL-5 cells.
The effect of 5,8,11,14-eicosatetraynoic acid (ETYA), an inhibitor of lipoxygenase and cytochrome P-450 epoxygenase enzymes, on calcium fluxes was investigated in Fura 2 loaded rat thyroid FRTL-5 cells. ETYA per se released sequestered calcium. ETYA also inhibited calcium influx in thapsigargin-stimulated cells in dose-dependent manner. Addition of calcium to cells treated with ETYA and stimulated with thapsigargin in a calcium-free buffer resulted in a blunted increase in intracellular free calcium compared with the response in control cells. In addition, ETYA per se acidified the cytosol in a dose-dependent manner. Acidification of the cytosol with the K+/H+ ionophore nigericin also decreased thapsigargin-induced calcium entry, but not to the same extent as that seen in cells treated with ETYA. The results suggest that ETYA is a potent modulator of calcium entry, and that part of the inhibitory effect of ETYA may be due to the ETYA-induced acidification of the cytosol.
Ekokoski
E
E
Department of Zoology, University of Helsinki, Finland.
Törnquist
K
K
D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D016257:Fura-2; D006863:Hydrogen-Ion Concentration; D051381:Rats; D013729:Terpenes / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D019284:Thapsigargin; D013961:Thyroid Gland / Q000187:drug effects*
D013729:Terpenes; D015117:5,8,11,14-Eicosatetraynoic Acid; D019284:Thapsigargin; D002118:Calcium; D016257:Fura-2