PAGE 2 OF 2 Another potential target is the KCC2 transporter on
spinal-cord neurons. One of the characteristics of chronic pain
is an increased concentration of chloride ions in neurons, which
causes them to fire in a hyperexcited manner. Because a normal-
functioning KCC2 removes chloride from the cells, something
happens in chronic pain that causes the KCC2 to down-regulate
and allow for a rise in chloride concentration. We've shown that
both the activation of P2X4 and the rise in intracellular
chloride concentrations are necessary for maintaining chronic
pain. In addition to finding new approaches to treating chronic
pain, we need better ways of diagnosing it. Individuals with
intractable pain often stop talking about their problem because
few people believe them. It's no surprise, then, that many
patients with this condition become depressed and may even begin
to prefer the thought of death to living with their intense
pain. An objective diagnostic test would allow people with
neuropathic pain to say “my m