Most of released norepinephrine is?

The process of neurotransmitter release and subsequent fate of norepinephrine involves multiple pathways, and the majority of released norepinephrine is indeed taken back into the nerve terminal through reuptake. This reuptake mechanism is primarily facilitated by the norepinephrine transporter (NET), which actively transports norepinephrine back into the presynaptic neuron from the synaptic cleft. This process is crucial for terminating the action of norepinephrine and recycling it for future neurotransmission.

The other options represent alternative fates of norepinephrine but occur to a lesser extent compared to reuptake. While monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) are enzymes that metabolize norepinephrine, they play a more minor role in the immediate fate of released norepinephrine compared to reuptake. Similarly, while some norepinephrine may diffuse into the plasma, this is not the primary mechanism for handling released norepinephrine in the synaptic space. Thus, the prominence of reuptake into the nerve terminal solidifies it as the most significant pathway following norepinephrine release.