P sub(2)-purinoceptor-activated membrane currents and inositol tetrakisphosphate formation are blocked by suramin

The effect of suramin on the ATP-induced response in vas deferens DDT sub(1) MF-2 smooth muscle cells was studied. Stimulation of P sub(2)-purinoceptors by ATP caused a change in membrane currents, measured by using the whole-cell patch-clamp configuration, and enhanced the formation of inositol phosphates, as analysed by high performance liquid chromatography. The ATP-induced membrane current consisted of a triphasic response, carried by a fast inward current, followed by a transient outward current and a sustained inward current. Inositol tetrakisphosphate (InsP sub(4)) formation increased in the presence of ATP. The results indicate that suramin inhibits ATP-activated cellular processes in DDT sub(1) MF-2 vas deferens cells, most likely by acting on P sub(2)-purinoceptors.