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 ethacrynic acid - induced convulsions , these neurotransmitter systems may be differentially modulated , probably through activation of glutaminergic neurons in the brain .
### Output Text:
In <span class="chemical">ethacrynic acid</span> - induced convulsions , these neurotransmitter systems may be differentially modulated , probably through activation of glutaminergic neurons in the brain . 