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: In these dogs , the prodysrhythmic response to epinephrine was also mitigated by preceding bupivacaine .
### Output Text:
In these dogs , the prodysrhythmic response to <span class="chemical">epinephrine</span> was also mitigated by preceding <span class="chemical">bupivacaine</span> . 