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: After a single oral dose of 4 mg / kg indomethacin ( IDM ) to sodium and volume depleted rats plasma renin activity ( PRA ) and systolic blood pressure fell significantly within four hours .
### Output Text:
After a single oral dose of 4 mg / kg <span class="chemical">indomethacin</span> ( <span class="chemical">IDM</span> ) to <span class="chemical">sodium</span> and volume depleted rats plasma renin activity ( PRA ) and systolic blood pressure fell significantly within four hours . 