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: Support for adrenaline - hypertension hypothesis : 18 hour pressor effect after 6 hours adrenaline infusion .
### Output Text:
Support for <span class="chemical">adrenaline</span> - hypertension hypothesis : 18 hour pressor effect after 6 hours <span class="chemical">adrenaline</span> infusion . 