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: The percentage of vasoconstriction of the right coronary artery was significantly higher than that of the left coronary artery .
### Output Text:
The percentage of vasoconstriction of the right coronary artery was significantly higher than that of the left coronary artery . 