ABSTRACT
The purine nucleotides, adenosine 5'-monophosphate, adenosine 5'-diphosphate, and adenosine 5'-triphosphate (AMP, ADP, and ATP), historically are best known for their roles in cellular energy metabolism and in nucleic acid synthesis. The purine nucleotides are also known to serve as intracellular chemical signals; cyclic AMP and cyclic guanosine monophosphate (cyclic GMP) are particularly important in this respect. Biochemical studies in the laboratory have shown that the aesthetasc sensilla of P. argus also have ectoenzymes that dephosphorylate nucleotides, as well as a specific uptake system that internalizes adenosine. The kinetics of AMP dephosphorylation by sensillar 5'-ectonucleotidase, when coupled with what is known about the temporally discrete nature of olfactory sampling by the lobster, suggested that the conversion of AMP to adenosine could affect the response of AMP-best purinoceptors to this odorant. The inhibition of the sensillar ecto-AMPase activity can enhance the electrophysiological response of AMP-best cells to AMP.
