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: Preservation of renal blood flow during hypotension induced with fenoldopam in dogs .
### Output Text:
Preservation of renal blood flow during hypotension induced with <span class="chemical">fenoldopam</span> in dogs . 