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: Enhanced stimulus - induced neurotransmitter overflow in epinephrine - induced hypertensive rats is not mediated by prejunctional beta - adrenoceptor activation .
### Output Text:
Enhanced stimulus - induced neurotransmitter overflow in <span class="chemical">epinephrine</span> - induced hypertensive rats is not mediated by prejunctional beta - adrenoceptor activation . 