One of the neurotransmitters sympathetic nervous system that increases heart rate and constricts smooth muscle in blood vessels to raise pressure fight or flight response is?

Epinephrine(Adrenaline) and norepinephrine are the primary neurotransmitters of the sympathetic nervous system

During Fight or Flight Response:

-Epinephrine/Adrenaline: Is mainly secreted during emergency situations (fight and flight). Activates sympathetic system, thus increase heart rate which result in more efficient delivery of oxygen. As blood vessel contracts there will be rapid increase in the blood pressure due to increased force and blood pumped in the veins.