Purine and pyrimidine mononucleotides depolarise neurones of explanted amphibian sympathetic ganglia

Abstract

ADENINE nucleotides and nucleosides have been proposed as neurotransmitters^1–3, in part based on their ability to inhibit spike activity in several peripheral^1,4,5 and central^2,5,6 sites. Only one preliminary study² has utilised intracellular recording to determine mechanisms of action of the purines in neurones. Because of their large size and simplified input-output relationships, neurones of sympathetic ganglia are a favourable model for intracellular recording. Although several studies have shown effects of ATP on peripheral ganglia^7,8, none utilised intracellular recording nor checked specificity of responses with other purine and pyrimidine nucleic acid components. Therefore, we examined the effects of several purine and pyrimidine derivatives by intracellular recording of bullfrog sympathetic neurones in explant cultures. Our findings show pronounced depolarisations with the di- and triphosphoribo derivatives of several pyrimidine and purine bases, with the uridine nucleotides emerging as the most potent of all the compounds.