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: Mechanisms of myocardial ischemia induced by epinephrine : comparison with exercise - induced ischemia .
### Output Text:
Mechanisms of myocardial ischemia induced by <span class="chemical">epinephrine</span> : comparison with exercise - induced ischemia . 