ADP-ATP Exchange in Internally Dialyzed Squid Giant Axons

Paul de Weer, Gerda E. Breitwieser, H. Gilbert Smith, Brian G. Kennedy

Research output: Contribution to journalArticlepeer-review


This chapter discusses the adenosine triphosphate–adenosine diphosphate (ADP–ATP) exchange in internally dialyzed squid giant axons. Experiments were designed to test whether the sodium pump or Na,K–ATPase of internally dialyzed squid giant axons can catalyze ADP-ATP exchange under conditions where ouabain–sensitive sodium–sodium (Na–Na) exchange is known to take place. Na–Na exchange is electroneutral, requires ADP as well as ATP, but does not hydrolyze the latter. Because one of the reactions catalyzed by membrane–bound Na,K–ATPase is a sodium-dependent ADP-ATP exchange, it has been proposed that Na–Na exchange and ADP-ATP exchange are manifestations of a single molecular operation. The chapter also presents a schematic summary of exchanges between internal perfusion capillary and axoplasm, both containing ATP and ADP in the steady state. Under the experimental conditions, the sodium-carrying enzyme can shuttle Na+ several times across the membrane before ATP is released.

Original languageEnglish (US)
Pages (from-to)665-669
Number of pages5
JournalCurrent Topics in Membranes and Transport
Issue numberC
StatePublished - Jan 1 1983
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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