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: Insulin treatment also prevented the increases in contractile responses of bladder body strips from diabetic rats to nerve stimulation , ATP , and bethanechol .
### Output Text:
Insulin treatment also prevented the increases in contractile responses of bladder body strips from diabetic rats to nerve stimulation , <span class="chemical">ATP</span> , and <span class="chemical">bethanechol</span> . 