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: Renal blood flow ( RBF ) increased during fenoldopam - induced hypotension 11 + / - 7 per cent and decreased 21 + / - 8 per cent during sodium nitroprusside - induced hypotension ( P less than 0 . 01 ) .
### Output Text:
Renal blood flow ( RBF ) increased during <span class="chemical">fenoldopam</span> - induced hypotension 11 + / - 7 per cent and decreased 21 + / - 8 per cent during <span class="chemical">sodium</span> <span class="chemical">nitroprusside</span> - induced hypotension ( P less than 0 . 01 ) . 