Pharmacological and molecular characterization of P2X receptors in rat pelvic ganglion neurons. Br J Pharmacol

Royal Free Academy of PMC, Londinium, England, United Kingdom
British Journal of Pharmacology (Impact Factor: 4.84). 09/1998; 125(4):771 - 781. DOI: 10.1038/sj.bjp.0702118


1The presence and characteristics of P2X receptors on neurons of the rat major pelvic ganglia (MPG) have been studied using whole cell voltage-clamp, in situ hybridization and immunohistochemistry.2Rapid application of ATP (100 μM) to isolated rat MPG neurons induced moderately large inward currents (0.33–5.3 nA) in 39% of cells (108/277). The response to ATP occurred very rapidly, with an increase in membrane conductance, and desensitized slowly.3The concentration-response curve for ATP yielded an EC50 of 58.9 μM. The agonist profile was ATP2MeSATP=ATPS>BzATP, while ,β-MeATP, β,-MeATP, UTP and ADP were all inactive at concentrations up to 100 μM.4The response to ATP was antagonized by suramin (pA2=5.6), reactive blue-2 (IC50=0.7 μM) and pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS).5Lowering the pH from 7.4 to 6.8 produced a marked potentiation (to 339% of control) of the responses to ATP (30 μM), while raising the pH to 8.0 attenuated the responses (to 20% of control). The EC50s for ATP were 28.8, 58.9 and 264 μM at pH 6.8, 7.4 and 8.0, respectively.6Co-application of ATP with Zn2+ produced a marked enhancement of the responses to ATP, with an EC50 of 9.55 μM. In the presence of Zn2+ (30 μM), the EC50 for ATP was decreased to 4.57 μM.7In situ hybridization revealed that the P2X receptor transcripts levels in rat MPG neurons are P2X2>P2X4>P2X1, P2X3, P2X5 and P2X6. The immunohistochemical staining revealed a small number of neurons with strong P2X2 immunoreactivity.8In conclusion, our results indicate that there are P2X receptors present on MPG neurons. The pharmacological characteristics of these receptors, the in situ hybridization and immunohistochemical evidence are consistent with them being of the P2X2 subtype, or heteromultimers, with P2X2 being the dominant component.British Journal of Pharmacology (1998) 125, 771–781; doi:10.1038/sj.bjp.0702118

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    • "eurones A 1 P2X 2 , P2X 3 , P2X 4 , P2Y 1 , P2Y 2 , P2Y 4 , P2Y 11 Neuronal - effector transmission ; pre - and postsynaptic modulation ; Ca 2+ signalling ; control of excitability via opening of ion channels Ginsborg & Hirst ( 1972 ) , Hayashi et al . ( 1978 ) , Horackova et al . ( 1994 ) , Nishimura & Tokimasa ( 1996 ) , Sun & Stanley ( 1996 ) , Zhong et al . ( 1998 , 2000"
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    ABSTRACT: The purinergic signalling system is one of the most ancient and arguably the most widespread intercellular signalling system in living tissues. In this review we present a detailed account of the early developments and current status of purinergic signalling. We summarize the current knowledge on purinoceptors, their distribution and role in signal transduction in various tissues in physiological and pathophysiological conditions.
    Full-text · Article · Mar 2010 · Acta Physiologica
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    • "In rat pelvic neurons, suramin (100 µM) practically abolishes the response to ATP 100 µM (Zhong et al., 1998). Here, in rat OTG neurons, a 2 min pre-incubation with suramin (100 µM) reversibly inhibited the response evoked by αβ-meATP (30 µM) to 8.5 ± 2% (n = 6) of the control, while the response evoked by ATP was reduced to 27 ± 1.2% of the control (Fig. 5A). "
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    ABSTRACT: To elucidate the pharmacological profile of P2X receptors and the probable expression of P2Y receptors in otic ganglion neurons from 17-day-old rats, single neurons were enzymatically isolated and maintained in tissue culture for up to 30 h. Whole-cell voltage-clamp recording was carried out at a holding potential of -60 mV. Most otic ganglion neurons responded to adenosine 5'-triphosphate (ATP), 2-methylthio ATP (2-MeSATP) and alpha,beta-methylene ATP (alphabeta-meATP) with sustained currents and EC(50) values of 19 microM, 47 microM and 94 microM, respectively. 2',3'-O-trinitrophenyl-ATP (TNP-ATP) inhibited the response to alphabeta-meATP and ATP with an IC(50) values of 3.9 nM and 18.3 nM, respectively, which was closed to that observed in nodose neurons. The response to ATP was antagonized by suramin and cibacron blue. The dose-response curve of suramin against ATP response at a pH of 6.5 was shifted to the left compared to that at a pH of 7.4. Diinosine pentaphosphate (Ip(5)I), which blocks P2X(3), but not P2X(2/3)-mediated responses, had no effect on the currents evoked by ATP or alphabeta-meATP. In some neurons, uridine 5'-triphosphate (UTP) induced a tiny, but long-lasting current with a mean amplitude of 0.034+/-0.011 nA. Reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed the expression of mRNAs for P2X(2), P2X(3), P2X(4), P2X(6) and P2X(7), but not for P2X(1) and P2X(5) receptors in otic ganglion. In conclusion, in rat otic ganglion neurons, P2X(2/3) heteromultimer receptors dominate, but P2X(7) and P2Y(2) or P2Y(4) receptors also play roles.
    Full-text · Article · Jul 2008 · Life Sciences
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    • "Single neurones from DRG, nodose, SCG and coeliac ganglia of 6-to 8-month-old mice were enzymatically isolated as previously described (Zhong et al. 1998). Briefly, mice were killed by CO 2 inhalation. "
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    ABSTRACT: Extracellular ATP plays a role in nociceptive signalling and sensory regulation of visceral function through ionotropic receptors variably composed of P2X2 and P2X3 subunits. P2X2 and P2X3 subunits can form homomultimeric P2X2, homomultimeric P2X3, or heteromultimeric P2X2/3 receptors. However, the relative contribution of these receptor subtypes to afferent functions of ATP in vivo is poorly understood. Here we describe null mutant mice lacking the P2X2 receptor subunit (P2X2-/-) and double mutant mice lacking both P2X2 and P2X3 subunits (P2X2/P2X3(Dbl-/-)), and compare these with previously characterized P2X3-/- mice. In patch-clamp studies, nodose, coeliac and superior cervical ganglia (SCG) neurones from wild-type mice responded to ATP with sustained inward currents, while dorsal root ganglia (DRG) neurones gave predominantly transient currents. Sensory neurones from P2X2-/- mice responded to ATP with only transient inward currents, while sympathetic neurones had barely detectable responses. Neurones from P2X2/P2X3(Dbl-/-) mice had minimal to no response to ATP. These data indicate that P2X receptors on sensory and sympathetic ganglion neurones involve almost exclusively P2X2 and P2X3 subunits. P2X2-/- and P2X2/P2X3(Dbl-/-) mice had reduced pain-related behaviours in response to intraplantar injection of formalin. Significantly, P2X3-/-, P2X2-/-, and P2X2/P2X3(Dbl-/-) mice had reduced urinary bladder reflexes and decreased pelvic afferent nerve activity in response to bladder distension. No deficits in a wide variety of CNS behavioural tests were observed in P2X2-/- mice. Taken together, these data extend our findings for P2X3-/- mice, and reveal an important contribution of heteromeric P2X2/3 receptors to nociceptive responses and mechanosensory transduction within the urinary bladder.
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