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: Intrarenal infusion of noradrenaline caused hypertension at doses which did not do so when infused intravenously .
### Output Text:
Intrarenal infusion of <span class="chemical">noradrenaline</span> caused hypertension at doses which did not do so when infused intravenously . 