system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Nitric oxide is produced in
assistant
The correct answer is  Nitric oxide is formed from Arginine, released from endothelial cells and acts through cGMP to cause vasodilation. 
It is also believed to be involved in gastrointestinal smooth muscle relaxation by acting as a neurotransmitter.