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: Sensitivity of cardiac component of baroreflex ( CCB ) , expressed as a slope of the regression line was determined from relationships between systolic arterial pressure ( SAP ) and HR period ( HRp ) during phenylephrine ( Phe ) - induced hypertension and sodium nitroprusside ( SN ) - induced hypotension .
### Output Text:
Sensitivity of cardiac component of baroreflex ( CCB ) , expressed as a slope of the regression line was determined from relationships between systolic arterial pressure ( SAP ) and HR period ( HRp ) during <span class="chemical">phenylephrine</span> ( <span class="chemical">Phe</span> ) - induced hypertension and <span class="chemical">sodium nitroprusside</span> ( <span class="chemical">SN</span> ) - induced hypotension . 