Investigating the functional expression of the novel P2Y14 receptor in porcine isolated pancreatic arteries

Mouhamed Alsaqati, Susan L.F. Chan, Vera Ralevic. School of Biomedical Sciences, Nottingham University, Nottingham, UK

The P2Y14 receptor is the most recent member of the P2Y of receptors for adenine and uridine nucleotides and nucleotide sugars. It is activated by UDP, UDP-glucose and its analogues, besides the synthetic analogue MRS 2690 (diphosphoric acid 1-α-D-glucopyranosyl ester 2-[(4\'-methylthio)uridin-5\'\'-yl] ester), which has been shown to be 7-10 fold more potent than UDP-glucose. The aim of this study was to investigate the functional expression of the P2Y14 receptor in porcine isolated pancreatic arteries. Segments of pancreatic arteries were prepared for isometric tension recording in oxygenated Krebs-Henseleit buffer warmed to 37oC. UDP-glucose (1 µM – 1 mM), UDP (1 µM – 1 mM) and MRS 2690 (1 µM – 30 µM) were applied cumulatively after preconstriction with U46619 (10 - 100 nM), a thromboxane A2-mimetic. Agonists were investigated in the absence and presence of compound-2, a P2Y14 receptor selective antagonist (Guay et al., 2011) (kindly donated by Merck Sharp & Dohme). UDP-glucose, UDP and MRS 2690 induced concentration-dependent contraction with a rank order of potency of MRS 2690 (10-fold) > UDP-glucose ≥ UDP. Contraction was significantly reduced in the presence of Compound-2; the contraction to 100 µM UDP-glucose and to 10 µM MRS 2690 was reduced by 55 ± 10% (P < 0.05, n=7) and by 46 ± 9% (P < 0.01, n=9) respectively in the presence of the antagonist. In separate experiments, an enhanced UDP-glucose response, by 930 ± 108% (P < 0.001, n=11), was uncovered if the tissue was precontracted with U46619, and relaxed back to baseline with 1 µM forskolin before the addition of UDP-glucose. The relative potencies of UDP, UDP-glucose and MRS 2690 in eliciting vasoconstriction in pancreatic arteries, together with the inhibition that occurs in the presence of a P2Y14 receptor selective antagonist are consistent with an involvement of P2Y14 receptors in porcine isolated pancreatic arteries. Augmentation of the contractile response to UDP-glucose after contraction with U46619 and relaxation with forskolin suggests that cyclic AMP-dependent mechanisms are involved in the response to UDP-glucose which shows P2Y14 is involved in heterotrimeric Gi-protein-mediated signalling.

Guay D, Beaulieu C, Belley M, Crane SN, DeLuca J, Gareau Y, et al. (2011). Bioorganic & Medicinal Chemistry Letters21(10): 2832-2835.

*Author for correspondence