This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
The following smooth muscle relaxants act by affecting calcium release except 
Select and explain. 
A. Dantrolene, B. Prazosin, C. Metolazone, D. Nifedipine
B: Prazosin
Answer: B: Prazosin 
Explanation: Prazosin is alpha-1 blocker .