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: These rats also showed declines in left ventricular systolic pressure , maximum and minimum rate of developed left ventricular pressure , and elevation of left ventricular end - diastolic pressure and ST - segment .
### Output Text:
These rats also showed declines in left ventricular systolic pressure , maximum and minimum rate of developed left ventricular pressure , and elevation of left ventricular end - diastolic pressure and ST - segment . 