Antagonistic properties of four suramin-related compounds at vascular purine P2X receptors in the pithed rat.

The dose-response curve for the vasopressor effect of alpha, beta-methylene ATP in pithed rats was influenced by four suramin-related drugs (each at 100 mumol/kg). The curve was shifted to the right by a factor of 8 by 'compound 3' and by a factor of 2 by two other derivatives, but was not affected by the fourth analogue. Compound 3 had no effect on the vasopressor response to noradrenaline or neuropeptide Y. In conclusion, compound 3 is a purine P2X receptor antagonist which is approximately as potent as suramin, and which, like suramin, does not exhibit antagonistic properties at alpha-adrenoceptors and neuropeptide y receptors.