The P2Y1 purinergic receptor expressed by enteric neurones in guinea‐pig intestine

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Abstract
Electrophysiological recording methods provided evidence for presynaptic release of ATP from enteric neurones and postganglionic sympathetic fibres in the enteric nervous system (ENS) of guinea‐pig intestine (J Physiol Lond 2003; 550: 493–504). The released ATP acted at postsynaptic P2Y1 receptors to evoke slow synaptic excitation in neurones in the submucosal division of the ENS. Here, we report the cloning and characterization of the P2Y1 receptor, which was found in the guinea‐pig submucosal layer. A 1178 bp cDNA clone was isolated from guinea‐pig submucosal RNA by reverse transcription polymerase chain reaction (RT–PCR). The cDNA contained an open‐reading frame of 1119 bp, encoding a 373 amino acid polypeptide of the same length and with 95% identity to the human P2Y1 receptor. Stable expression of the guinea‐pig cDNA in human embryonic kidney (HEK)293 cells was accompanied by a marked increase in sensitivity for elevation of free intracellular calcium evoked by ATP or related nucleotides. The potency order for ATP and its analogues was: 2‐methio‐adenosine diphosphate > 2‐methio‐adenosine triphosphate > ADP > ATP‐γ‐S > ATP. The selective P2Y1 receptor antagonist, MRS2179, was a competitive antagonist for the receptor with a pA2 value of 6.5. The results add to existing evidence for expression of a functional P2Y1 purinergic receptor in neurones of the submucosal division of the ENS.

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