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: ATP ( 10 dogs ) or SNP ( 10 dogs ) was administered to reduce mean arterial pressure by 30 % to 70 % of control .
### Output Text:
<span class="chemical">ATP</span> ( 10 dogs ) or <span class="chemical">SNP</span> ( 10 dogs ) was administered to reduce mean arterial pressure by 30 % to 70 % of control . 