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: Experiments in vitro showed that acetylcholine - induced catecholamine release from bovine adrenal medulla is depressed as much as 50 % by 0 . 3 mM NH4Ac and KCl - induced contractions of guinea - pig ileum were inhibited 20 % by 5 mM NH4Ac .
### Output Text:
Experiments in vitro showed that <span class="chemical">acetylcholine</span> - induced <span class="chemical">catecholamine</span> release from bovine adrenal medulla is depressed as much as 50 % by 0 . 3 mM <span class="chemical">NH4Ac</span> and <span class="chemical">KCl</span> - induced contractions of guinea - pig ileum were inhibited 20 % by 5 mM <span class="chemical">NH4Ac</span> . 