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 the presence of coronary artery stenosis , 3 - min periods of intracoronary ISO infusion ( 10 ng / kg / min ) increased heart rate and maximal rate of left ventricular pressure rise , which resulted in a decrease in percentage segmental shortening and ST - segment elevation of the epicardial electrocardiogram .
### Output Text:
In the presence of coronary artery stenosis , 3 - min periods of intracoronary <span class="chemical">ISO</span> infusion ( 10 ng / kg / min ) increased heart rate and maximal rate of left ventricular pressure rise , which resulted in a decrease in percentage segmental shortening and ST - segment elevation of the epicardial electrocardiogram . 