What is the effect of norepinephrine on the heart?

It increases the heart rate

Explanation:

Norepinephrine or noradrenalin is a neurontransmitter that controls many body functions as part of the sympathetic nervous system. This means that its role is to increase body movement and to prepare organism for "fight and flight" reactions. Its functions are:

Norepinephrine achieves its function by binding to its cell membrane receptors-alpha and beta adrenergic G protein-coupled receptors.

substitution is the answer in this case