In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.

[EX Q]: Synaptotagmin 1 is required for vesicular Ca(2+) /H(+) -antiport activity.
[EX A]: Ca(2+)

[EX Q]: The atypical antidepressant mianserin exhibits agonist activity at kappa-opioid receptors.
[EX A]: mianserin

[EX Q]: Clinical assessment of norepinephrine transporter blockade through biochemical and pharmacological profiles.
[EX A]:
norepinephrine