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: Changes of sodium and ATP affinities of the cardiac ( Na , K ) - ATPase during and after nitric oxide deficient hypertension .
### Output Text:
Changes of <span class="chemical">sodium</span> and <span class="chemical">ATP</span> affinities of the cardiac ( <span class="chemical">Na</span> , <span class="chemical">K</span> ) - ATPase during and after <span class="chemical">nitric oxide</span> deficient hypertension . 