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: Subacute effects of propranolol and B 24 / 76 on isoproterenol - induced rat heart hypertrophy in correlation with blood pressure .
### Output Text:
Subacute effects of <span class="chemical">propranolol</span> and B 24 / 76 on <span class="chemical">isoproterenol</span> - induced rat heart hypertrophy in correlation with blood pressure . 