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: Vasodilation of large and small coronary vessels and hypotension induced by cromakalim and pinacidil were not affected by prior combined beta adrenergic and muscarinic receptors blockade but drug - induced tachycardia was abolished .
### Output Text:
Vasodilation of large and small coronary vessels and hypotension induced by <span class="chemical">cromakalim</span> and <span class="chemical">pinacidil</span> were not affected by prior combined <span class="chemical">beta adrenergic and muscarinic receptors blockade</span> but drug - induced tachycardia was abolished . 