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 superoxide scavenger tempol ( 30 , 100 , and 300 micromol kg ( - 1 ) , IV ) did not change arterial pressure in control rats but caused a dose - dependent decrease in LNNA rats ( - 18 + / - 8 , - 26 + / - 15 , and - 54 + / - 11 mm Hg ) .
### Output Text:
The <span class="chemical">superoxide</span> scavenger <span class="chemical">tempol</span> ( 30 , 100 , and 300 micromol kg ( - 1 ) , IV ) did not change arterial pressure in control rats but caused a dose - dependent decrease in <span class="chemical">LNNA</span> rats ( - 18 + / - 8 , - 26 + / - 15 , and - 54 + / - 11 mm Hg ) . 