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: In microdialysis experiments , the lines did not differ in basal release of ACh , and 50 mM KCl increased ACh output in both lines of mice .
### Output Text:
In microdialysis experiments , the lines did not differ in basal release of <span class="chemical">ACh</span> , and 50 mM <span class="chemical">KCl</span> increased <span class="chemical">ACh</span> output in both lines of mice . 