Article date: January 2003
By: Helmut Kubista, Stefan G Lechner, Angelika M Wolf, Stefan Boehm in Volume 138, Issue 2, pages 343-350
In PC12 cells, adenine nucleotides inhibit voltage‐activated Ca2+ currents and adenylyl cyclase activity, and the latter effect was reported to involve P2Y12 receptors. To investigate whether these two effects are mediated by one P2Y receptor subtype, we used the antithrombotic agents 2‐methylthio‐AMP (2‐MeSAMP) and N6‐(2‐methyl‐thioethyl)‐2‐(3,3,3‐trifluoropropylthio)‐β,γ‐dichloromethylene‐ATP (AR‐C69931MX).
ADP reduced A2A receptor‐dependent cyclic AMP synthesis with half maximal effects at 0.1–0.17 μM. In the presence of 30 μM 2‐MeSAMP or 100 nM AR‐C69931MX, concentration response curves were shifted to the right by factors of 39 and 30, indicative of pA2 values of 6.1 and 8.5, respectively.
The inhibition of Ca2+ currents by ADP was attenuated by 10–1000 nM AR‐C69931MX and by 3–300 μM 2‐MeSAMP. ADP reinhibited Ca2+ currents after removal of 2‐MeSAMP within less than 15 s, but required 2 min to do so after removal of AR‐C69931MX.
ADP inhibited Ca2+ currents with half maximal effects at 5–20 μM. AR‐C69931MX (10–100 nM) displaced concentration response curves to the right, and the resulting Schild plot showed a slope of 1.09 and an estimated pKB value of 8.7. Similarly, 10–100 μM 2‐MeSAMP also caused rightward shifts resulting in a Schild plot with a slope of 0.95 and an estimated pKB of 5.4.
The inhibition of Ca2+ currents by 2‐methylthio‐ADP and ADPβS was also antagonized by AR‐C69931MX, which (at 30 nM) caused a rightward shift of the concentration response curve for ADPβS by a factor of 3.8, indicative of a pA2 value of 8.1.
These results show that antithrombotic drugs antagonize the inhibition of neuronal Ca2+ channels by adenine nucleotides, which suggests that this effect is mediated by P2Y12 receptors.
In PC12 cells, adenine nucleotides inhibit voltage‐activated Ca2+ currents and adenylyl cyclase activity, and the latter effect was reported to involve P2Y12 receptors. To investigate whether these two effects are mediated by one P2Y receptor subtype, we used the antithrombotic agents 2‐methylthio‐AMP (2‐MeSAMP) and N6‐(2‐methyl‐thioethyl)‐2‐(3,3,3‐trifluoropropylthio)‐β,γ‐dichloromethylene‐ATP (AR‐C69931MX).
ADP reduced A2A receptor‐dependent cyclic AMP synthesis with half maximal effects at 0.1–0.17 μM. In the presence of 30 μM 2‐MeSAMP or 100 nM AR‐C69931MX, concentration response curves were shifted to the right by factors of 39 and 30, indicative of pA2 values of 6.1 and 8.5, respectively.
The inhibition of Ca2+ currents by ADP was attenuated by 10–1000 nM AR‐C69931MX and by 3–300 μM 2‐MeSAMP. ADP reinhibited Ca2+ currents after removal of 2‐MeSAMP within less than 15 s, but required 2 min to do so after removal of AR‐C69931MX.
ADP inhibited Ca2+ currents with half maximal effects at 5–20 μM. AR‐C69931MX (10–100 nM) displaced concentration response curves to the right, and the resulting Schild plot showed a slope of 1.09 and an estimated pKB value of 8.7. Similarly, 10–100 μM 2‐MeSAMP also caused rightward shifts resulting in a Schild plot with a slope of 0.95 and an estimated pKB of 5.4.
The inhibition of Ca2+ currents by 2‐methylthio‐ADP and ADPβS was also antagonized by AR‐C69931MX, which (at 30 nM) caused a rightward shift of the concentration response curve for ADPβS by a factor of 3.8, indicative of a pA2 value of 8.1.
These results show that antithrombotic drugs antagonize the inhibition of neuronal Ca2+ channels by adenine nucleotides, which suggests that this effect is mediated by P2Y12 receptors.
British Journal of Pharmacology (2003) 138, 343–350. doi:10.1038/sj.bjp.0705037
DOI: 10.1038/sj.bjp.0705037
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