The effect of prostaglandin E1 on ion currents of NG108-15 cells.
The aim of this study was to elucidate the mechanism by which prostaglandin E(1) (PGE(1)) acts on ion currents of whole-cell voltage-clamped NG108-15 neuroblastomaxglioma hybrid cells. Ruptured and perforated patch were used. The holding current at -70 mV, the current-voltage curve produced by ramp pulses from -70 to 0 mV and the T-type and hva (high-voltage-activated) Ca(2+) currents associated with rectangular pulses were recorded. Bath application of PGE(1) (0.2 or 3 microM) reversibly increased the holding current, an effect mimicked by the prostanoid agonist iloprost (5-50 nM). The PGE(1) effect was totally blocked by the cAMP-antagonist Rp-cAMPS whereas H-89, an inhibitor of protein kinase A (PKA), failed to inhibit it, even when applied in the fairly high bath concentration of 30 microM. PGE(1) and iloprost also inhibited the T-type and hva Ca(2+) currents and this effect of PGE(1) was likewise not prevented by H-89. In some of the cells, the PGE(1) effect on holding current could be mimicked by 8-pCPT-2Me-cAMP (100-300 microM), a selective agonist of Epac (exchange protein activated by cAMP), but unlike the PGE(1) effect its action was not abolished by Rp-cAMPS. The effect of PGE(1) on the the holding current and on the T-type Ca(2+) current was diminished when EGTA in the pipette solution was replaced by BAPTA, suggesting that Ca(2+) ions are involved in the PGE(1) effect. It is concluded that the PGE(1) effect is mediated by cAMP and Ca(2+) ions but not by PKA or Epac.
Meves
Hans
H
Physiologisches Institut, Universität des Saarlandes, Homburg-Saar, Germany. phhmev@uniklinik-saarland.de
D000527:Alprostadil / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects*; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D006801:Humans; D011760:Pyrrolidinones / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; D015220:Calcium Channels; D004963:Estrenes; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; D000242:Cyclic AMP; D000527:Alprostadil