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: The evoked increases in dural blood flow were also abolished by topical pre - administration of atropine ( 1 mm ) and [ Lys1 , Pro2 , 5 , Arg3 , 4 , Tyr6 ] - VIP ( 0 . 1 mm ) , a vasoactive intestinal polypeptide ( VIP ) antagonist , onto the exposed dura mater .
### Output Text:
The evoked increases in dural blood flow were also abolished by topical pre - administration of <span class="chemical">atropine</span> ( 1 mm ) and [ Lys1 , Pro2 , 5 , Arg3 , 4 , Tyr6 ] - VIP ( 0 . 1 mm ) , a vasoactive intestinal polypeptide ( VIP ) antagonist , onto the exposed dura mater . 