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: Clentiazem also did not prevent the enhanced responses to calcium seen in the epinephrine - treated animals , although the high dose of clentiazem partially attenuated the maximal response to calcium compared to epinephrine - treated animals .
### Output Text:
<span class="chemical">Clentiazem</span> also did not prevent the enhanced responses to <span class="chemical">calcium</span> seen in the <span class="chemical">epinephrine</span> - treated animals , although the high dose of <span class="chemical">clentiazem</span> partially attenuated the maximal response to <span class="chemical">calcium</span> compared to <span class="chemical">epinephrine</span> - treated animals . 