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: We therefore examined whether bupivacaine alters the dysrhythmogenicity of subsequent administration of epinephrine in conscious , healthy dogs and in anesthetized dogs with myocardial infarction .
### Output Text:
We therefore examined whether <span class="chemical">bupivacaine</span> alters the dysrhythmogenicity of subsequent administration of <span class="chemical">epinephrine</span> in conscious , healthy dogs and in anesthetized dogs with myocardial infarction . 