<Li> The unphosphorylated form of the pump has a higher affinity for Na ions than K ions, so the two bound K ions are released . ATP binds, and the process starts again . </Li> <P> The Na / K - ATPase is upregulated by cAMP . Thus, substances causing an increase in cAMP upregulate the Na / K - ATPase . These include the ligands of the G - coupled GPCRs . In contrast, substances causing a decrease in cAMP downregulate the Na / K - ATPase . These include the ligands of the G - coupled GPCRs . </P> <P> Note: Early studies indicated the opposite effect, but these were later found to be inaccurate due to additional complicating factors . </P> <P> The Na - K - ATPase can be pharmacologically modified by administrating drugs exogenously . </P>

The movement of sodium and potassium maintained by the na k pump