TY - JOUR T1 - Endothelin (ET)-1-Induced Inhibition of ATP Release from PC-12 Cells Is Mediated by the ET<sub>B</sub> Receptor: Differential Response to ET-1 on ATP, Neuropeptide Y, and Dopamine Levels JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 1109 LP - 1117 DO - 10.1124/jpet.104.081075 VL - 313 IS - 3 AU - A. Gardner AU - T. C. Westfall AU - H. Macarthur Y1 - 2005/06/01 UR - http://jpet.aspetjournals.org/content/313/3/1109.abstract N2 - During sympathetic neurotransmitter release, there is evidence for differential modulation of cotransmitter release by endothelin (ET)-1. Using nerve growth factor (NGF)-differentiated PC12 cells, the effects of ET-1 on K+-stimulated release of ATP, dopamine (DA), and neuropeptide Y (NPY) were quantified using high-pressure liquid chromatography or radioimmunoassay. ET-1, in a concentration-dependent manner, inhibited the release of ATP, but not DA and NPY. Preincubation with the ETA/B antagonist, PD 142893 (N-acetyl-β-phenyl-d-Phe-Leu-Asp-Ile-Ile-Trp), reversed the inhibitory effect of ET-1 on ATP release, which remained unaffected in the presence of the ETA-specific antagonist BQ123 [cyclo(d-Asp-Pro-d-Val-Leu-d-Trp)]. The ETB agonists, sarafotoxin 6c (Cys-Thr-Cys-Asn-Asp-Met-Thr-Asp-Glu-Glu-Cys-Leu-Asn-Phe-Cys-His-Gln-Asp-Val-Ile-Trp), BQ 3020 (N-acetyl-[Ala11,15]-endothelin 1 fragment 6-21Ac-Leu-Met-Asp-Lys-Glu-Ala-Val-Tyr-Phe-Ala-His-Leu-Asp-IIe-IIe-Trp), and IRL 1620 (N-succinyl-[Glu9, Ala11,15]-endothelin 1 fragment 8-21Suc-Asp-Glu-Glu-Ala-Val-Tyr-Phe-Ala-His-Leu-Asp-Ile-Ile-Trp), decreased K+-stimulated release of ATP in a dose-dependent manner, and this effect was reversed by the ETB antagonists RES 701-1 [cyclic (Gly1-Asp9) (Gly-Asn-Trp-His-Gly-Thr-Ala-Pro-Asp-Trp-Phe-Phe-Asn-Tyr-Tyr-Trp)] and BQ 788 (N-[N-[N-[(2,6-dimethyl-1-piperidinyl)carbonyl]-4-methyl-l-leucyl]-1-(methoxycarbonyl)-d-tryptophyl]-d-norleucine sodium salt). Preincubation of PC12 cells with pertussis toxin reversed the ET-1-induced inhibition of the K+-evoked ATP release. Real-time intracellular calcium level recordings were performed on PC-12 cell suspensions, and ET-1 induced a dose-dependent decrease in the K+-evoked calcium levels. Nifedipine, the L-type voltage-dependent Ca2+ channel antagonist, caused inhibition of the K+-stimulated ATP release, but the N-type Ca2+ channel antagonist, ω-conotoxin GVIA, did not reverse the effect on ATP release. These data suggest that ET-1 modulates the release of ATP via the ETB receptor and its associated Gi/o G-protein through attenuation of the influx of extracellular Ca2+ through L-type channels. The American Society for Pharmacology and Experimental Therapeutics ER -