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: However , the increase in release of ACh produced by the first application of KCl was 2 - fold higher in WSP versus WSR mice .
### Output Text:
However , the increase in release of <span class="chemical">ACh</span> produced by the first application of <span class="chemical">KCl</span> was 2 - fold higher in WSP versus WSR mice . 