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 effect of isoflurane - induced hypotension on glomerular function and renal blood flow was investigated in 20 human subjects .
### Output Text:
The effect of <span class="chemical">isoflurane</span> - induced hypotension on glomerular function and renal blood flow was investigated in 20 human subjects . 