In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The decreased abundance of NHE3 , BSC - 1 , TSC , and Na - K - ATPase may play a compensatory role to promote sodium excretion .
### Output Text:
The decreased abundance of NHE3 , BSC - 1 , TSC , and <span class="chemical">Na</span> - <span class="chemical">K</span> - ATPase may play a compensatory role to promote <span class="chemical">sodium</span> excretion . 