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: Isoproterenol - treated rats showed significant increases in the levels of lactate dehydrogenase , aspartate transaminase , creatine kinase and malondialdehyde and significant decreases in the activities of superoxide dismutase , catalase and glutathione peroxidase in serum and heart .
### Output Text:
<span class="chemical">Isoproterenol</span> - treated rats showed significant increases in the levels of <span class="chemical">lactate</span> dehydrogenase , <span class="chemical">aspartate</span> transaminase , <span class="chemical">creatine</span> kinase and <span class="chemical">malondialdehyde</span> and significant decreases in the activities of <span class="chemical">superoxide</span> dismutase , catalase and <span class="chemical">glutathione</span> peroxidase in serum and heart . 