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: Treatment with Ato improved endothelial function , reduced superoxide production and reduced SBP in Dex - treated SD rats .
### Output Text:
Treatment with <span class="chemical">Ato</span> improved endothelial function , reduced <span class="chemical">superoxide</span> production and reduced SBP in <span class="chemical">Dex</span> - treated SD rats . 