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: MAP in conscious SHR after chronic prazosin treatment was 14 % lower than in the untreated SHR ( n = 8 ) .
### Output Text:
MAP in conscious SHR after chronic <span class="chemical">prazosin</span> treatment was 14 % lower than in the untreated SHR ( n = 8 ) . 