Suramin selectively inhibits the non-adrenergic non-cholinergic inhibitory junction potential in the guinea-pig stomach.

In smooth muscle cells of the guinea-pig stomach fundus, transmural nerve stimulation evoked a cholinergic excitatory junction potential (e.j.p.) and, in the presence of atropine, a non-adrenergic non-cholinergic (NANC) inhibitory junction potential (i.j.p.). Suramin (> 10(-5) M), a putative inhibitor of the P2 purinoceptor, enhanced the e.j.p. amplitude and inhibited the i.j.p., with no significant effect on the membrane potential. Thus, a possible involvement of ATP in the generation of the NANC i.j.p. has to be considered.