Substance P is a neuropeptide that is involved in the natural regulation of many aspects of your cardiovascular system. Under normal circumstances it helps control vascular relaxation and thus blood pressure by enhancing the formation of nitric oxide. It also promotes the normal movement of fluids out of blood vessels for a variety of reasons. The main receptor for Substance P is called neurokinnin 1, NK1, which is located in many places throughout the body including the circulatory system and the heart itself. This means that substance P is a common regulatory compound used by your nervous system.

As it turns out, substance P is ...