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: These findings indicate that ischemia produced by epinephrine , as may occur during states of emotional distress , has a mechanism distinct from that due to physical exertion .
### Output Text:
These findings indicate that ischemia produced by <span class="chemical">epinephrine</span> , as may occur during states of emotional distress , has a mechanism distinct from that due to physical exertion . 