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 trimethaphan - induced hypotension was accompanied by a significant bradycardia in lesioned rats ( - 32 + / - 13 beats per minute ) but a tachycardia in sham rats ( + 33 + / - 12 beats per minute ) 1 day postlesion .
### Output Text:
The <span class="chemical">trimethaphan</span> - induced hypotension was accompanied by a significant bradycardia in lesioned rats ( - 32 + / - 13 beats per minute ) but a tachycardia in sham rats ( + 33 + / - 12 beats per minute ) 1 day postlesion . 