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: Bupivacaine antagonizes epinephrine dysrhythmogenicity in conscious dogs susceptible to VT and in anesthetized dogs with spontaneous postinfarct dysrhythmias .
### Output Text:
<span class="chemical">Bupivacaine</span> antagonizes <span class="chemical">epinephrine</span> dysrhythmogenicity in conscious dogs susceptible to VT and in anesthetized dogs with spontaneous postinfarct dysrhythmias . 