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: Cardiac functions depressed by pentobarbital ( 118 + / - 28 mg ; mean value + / - SD ) such that cardiac output and maximum rate of rise of left ventricular pressure ( LV dP / dt max ) had been reduced by about 35 % and 26 % of the respective controls were improved by denopamine ( 10 - 300 micrograms ) in a dose - dependent manner .
### Output Text:
Cardiac functions depressed by <span class="chemical">pentobarbital</span> ( 118 + / - 28 mg ; mean value + / - SD ) such that cardiac output and maximum rate of rise of left ventricular pressure ( LV dP / dt max ) had been reduced by about 35 % and 26 % of the respective controls were improved by <span class="chemical">denopamine</span> ( 10 - 300 micrograms ) in a dose - dependent manner . 