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: We hypothesized that increased venous smooth muscle ( venomotor ) tone plays a role in Nomega - nitro - L - arginine ( LNNA ) hypertension through these mechanisms .
### Output Text:
We hypothesized that increased venous smooth muscle ( venomotor ) tone plays a role in <span class="chemical">Nomega - nitro - L - arginine</span> ( <span class="chemical">LNNA</span> ) hypertension through these mechanisms . 