Effect of acute hypoxia on ATP-sensitive potassium currents in substantia gelatinosa neurons of juvenile rats.
Although hypoxia is known to affect membrane excitability of various neurons by various mechanisms, the effects of hypoxia on substantia gelatinosa (SG) neurons have not yet been elucidated. In whole-cell or perforated patch-clamp recordings from SG neurons, we showed that acute hypoxia induces a reversible hyperpolarization of -6.1+/-1.3 mV of the resting membrane potential and an outwards current of 9.48+/-1.71 pA at a holding potential of -60 mV. The reversal potentials of the hypoxia-induced current depended on [K(+)](o). The hypoxia-induced hyperpolarization and outwards current were abolished completely by BaCl(2), but not by CsCl. Glibenclamide, a blocker of K(ATP) channels, blocked the hypoxia-induced hyperpolarization. Pretreatment with cromakalim, an opener of K(ATP) channels, occluded the hypoxia-induced hyperpolarization. Any alteration by hypoxia was not observed in the presence of an internal solution with a high [ATP] (10 mM). The above results suggest that hypoxia-induced hyperpolarization in SG neurons is mediated by activation of K(ATP) channels.
Park
Yun Kyung
YK
Department of Biomedical Science, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Jung
Sung Jun
SJ
Yoo
Ji-Eun
JE
Kwak
Jiyeon
J
Lim
Wonil
W
Kim
Jun
J
D000208:Acute Disease; D000255:Adenosine Triphosphate / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D002586:Cesium / Q000494:pharmacology; D019806:Cromakalim / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010276:Parasympatholytics / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D013376:Substantia Gelatinosa / Q000166:cytology / Q000502:physiology*
D000889:Anti-Arrhythmia Agents; D010276:Parasympatholytics; D015221:Potassium Channels; D019806:Cromakalim; D002586:Cesium; D001464:Barium; D000255:Adenosine Triphosphate; D005905:Glyburide