title: Characterization of an ATP-sensitive K(+) channel in rat carotid body glomus cells.
abstract: Carotid body glomus (CB) cells express different types of K(+) channels such as TASK, BK, and Kv channels, and hypoxia has been shown to inhibit these channels. Here we report the presence of a ∼72-pS channel that has not been described previously in CB cells. In cell-attached patches with 150 mM K(+) in the pipette and bath solutions, TASK-like channels were present (∼15 and ∼36-pS). After formation of inside-out patches, a 72-pS channel became transiently active in ∼18% of patches. The 72-pS channel was K(+)-selective, inhibited by 2-4 mM ATP and 10-100 μM glybenclamide. The 72-pS channel was observed in CB cells isolated from newborn, 2-3 week and 10-12 week-old rats. Reverse transcriptase-PCR and immunocytochemistry showed that Kir6.1, Kir6.2, SUR1 and SUR2 were expressed in CB glomus cells as well as in non-glomus cells. Acute hypoxia (∼15 mmHg O(2)) inhibited TASK-like channels but failed to activate the 72-pS channel in cell-attached CB cells. K(+) channel openers (diazoxide, pinacidil, levcromakalim), sodium cyanide and removal of extracellular glucose also did not activate the 72-pS channel in the cell-attached state. The hypoxia-induced elevation of intracellular [Ca(2+)] was unchanged by glybenclamide or diazoxide. NaCN-induced increase in [Ca(2+)] was not affected by 10 μM glybenclamide but inhibited by 100 μM glybenclamide. Acute glucose deprivation did not elevate [Ca(2+)] in the presence or absence of glybenclamide. These results show that an ATP-sensitive K(+) channel is expressed in the plasma membrane of CB cells, but is not activated by short-term metabolic inhibition. The functional relevance of the 72-pS channel remains to be determined.
authors.affiliation: Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, United States. donghee.kim@rosalindfranklin.edu
authors.forename: Donghee
authors.initials: D
authors.lastname: Kim
authors.forename: Insook
authors.initials: I
authors.lastname: Kim
authors.forename: Justin R
authors.initials: JR
authors.lastname: Papreck
authors.forename: David F
authors.initials: DF
authors.lastname: Donnelly
authors.forename: John L
authors.initials: JL
authors.lastname: Carroll
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002344:Carotid Body / Q000166:cytology*; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000378:metabolism*; D003486:Cyanides / Q000494:pharmacology; D003981:Diazoxide / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D054086:KATP Channels / Q000235:genetics / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism; D064233:Sulfonylurea Receptors; D013549:Sweetening Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; C577509:Abcc8 protein, rat; C577512:Abcc9 protein, rat; D003486:Cyanides; D007004:Hypoglycemic Agents; D054086:KATP Channels; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D013549:Sweetening Agents; D014665:Vasodilator Agents; C092520:uK-ATP-1 potassium channel; D000255:Adenosine Triphosphate; D005947:Glucose; D003981:Diazoxide; D005905:Glyburide; D002118:Calcium