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: Acute myocardial ischemic injury was induced in rats by subcutaneous injection of isoproterenol ( 85 mg / kg ) , for two consecutive days .
### Output Text:
Acute myocardial ischemic injury was induced in rats by subcutaneous injection of <span class="chemical">isoproterenol</span> ( 85 mg / kg ) , for two consecutive days . 