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: Testosterone contributes to the development of hypertension and renal injury in male DS rats on HS diet possibly through upregulation of the intrarenal renin - angiotensin system .
### Output Text:
<span class="chemical">Testosterone</span> contributes to the development of hypertension and renal injury in male DS rats on HS diet possibly through upregulation of the intrarenal renin - <span class="chemical">angiotensin</span> system . 