Abstract
2-Methylthio ATP, noradrenaline, adenosine 5′-O-(2-thiodiphosphate) (ADP\S), α,\-methylene ATP, ATP and adenosine caused relaxation of guinea-pig isolated taenia caeci precontracted by carbachol, with potency decreasing in the order indicated. 4,4′-Diisothiocyanatostilbene-2,2′-disulphonate (DIDS) 10, 32 and 100 μM shifted the concentration-response curve of α,\-methylene ATP increasingly to the right, by the factor 141 at DIDS 100 μM. Concentration-response curves of the other agonists were not shifted to the right by DIDS 100 μM, except for the curve of ADP\S which was shifted by the factor 2.4. The relaxation produced by 2-methylthio ATP faded rapidly. When the fade was complete, further addition of 2-methylthio ATP or ATP did not elicit relaxation, whereas the relaxant effect of α, \-methylene ATP was unchanged. The results indicate that there are at least two relaxation-mediating P2-purinoceptors in guinea-pig taenia caeci, the P2Y-purinoceptor which is relatively insensitive to DIDS and a distinct receptor for α,\-methylene ATP which is very sensitive to DIDS.
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Dudeck, O., Bültmann, R. & Starke, K. Two relaxation-mediating P2-purinoceptors in guinea-pig taenia caeci. Naunyn-Schmiedeberg's Arch Pharmacol 351, 107–110 (1995). https://doi.org/10.1007/BF00169071
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DOI: https://doi.org/10.1007/BF00169071