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: Pimozide did not affect the actions of L - dopa on blood pressure and heart rate but completely blocked the enhancement of reflexes .
### Output Text:
<span class="chemical">Pimozide</span> did not affect the actions of <span class="chemical">L - dopa</span> on blood pressure and heart rate but completely blocked the enhancement of reflexes . 