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: Both CD - 832 and diltiazem , but not nifedipine , significantly reduced the increase in heart rate induced by ISO infusion .
### Output Text:
Both <span class="chemical">CD - 832</span> and <span class="chemical">diltiazem</span> , but not <span class="chemical">nifedipine</span> , significantly reduced the increase in heart rate induced by <span class="chemical">ISO</span> infusion . 