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: These results suggest that spasm provocation tests , which use an intracoronary injection of a relatively low dose of methylergonovine , have a high sensitivity in variant angina and the vasoreactivity of the right coronary artery may be greater than that of the other coronary arteries .
### Output Text:
These results suggest that spasm provocation tests , which use an intracoronary injection of a relatively low dose of <span class="chemical">methylergonovine</span> , have a high sensitivity in variant angina and the vasoreactivity of the right coronary artery may be greater than that of the other coronary arteries . 