The inhibitor of volume-regulated anion channels DCPIB activates TREK potassium channels in cultured astrocytes.
OBJECTIVE
The ethacrynic acid derivative, 4-(2-butyl-6,7-dichlor-2-cyclopentylindan-1-on-5-yl) oxobutyric acid (DCPIB) is considered to be a specific and potent inhibitor of volume-regulated anion channels (VRACs). In the CNS, DCPIB was shown to be neuroprotective through mechanisms principally associated to its action on VRACs. We hypothesized that DCPIB could also regulate the activity of other astroglial channels involved in cell volume homeostasis.


METHODS
Experiments were performed in rat cortical astrocytes in primary culture and in hippocampal astrocytes in situ. The effect of DCPIB was evaluated by patch-clamp electrophysiology and immunocytochemical techniques. Results were verified by comparative analysis with recombinant channels expressed in COS-7 cells.


RESULTS
In cultured astrocytes, DCPIB promoted the activation of a K(+)  conductance mediated by two-pore-domain K(+)  (K(2P) ) channels. The DCPIB effect occluded that of arachidonic acid, which activates K(2P)  channels K(2P)  2.1 (TREK-1) and K(2P)  10.1 (TREK-2) in cultured astrocytes. Immunocytochemical analysis suggests that cultured astrocytes express K(2P)  2.1 and K(2P)  10.1 proteins. Moreover, DCPIB opened recombinant K(2P)  2.1 and K(2P)  10.1 expressed in heterologous system. In brain slices, DCPIB did not augment the large background K(+)  conductance in hippocampal astrocytes, but caused an increment in basal K(+)  current of neurons.


CONCLUSIONS
Our results indicate that the neuroprotective effect of DCPIB could be due, at least in part, to activation of TREK channels. DCPIB could be used as template to build new pharmacological tools able to increase background K(+)  conductance in astroglia and neuronal cells.
Department of Human and General Physiology, University of Bologna, Bologna, Italy.
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L
Minieri
H
H
Pivonkova
M
M
Caprini
L
L
Harantova
M
M
Anderova
S
S
Ferroni
D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000502:physiology; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003517:Cyclopentanes / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007189:Indans / Q000494:pharmacology*; D007473:Ion Channels / Q000037:antagonists & inhibitors; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D024683:Potassium Channels, Tandem Pore Domain / Q000819:agonists* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
C443139:4-(2-butyl-6,7-dichlor-2-cyclopentyl-indan-1-one-5-yl)oxybutyric acid; D003517:Cyclopentanes; D007189:Indans; D007473:Ion Channels; D018696:Neuroprotective Agents; D024683:Potassium Channels, Tandem Pore Domain; C103742:potassium channel protein TREK-1