Interaction of acetylcholine with Kir6.1 channels heterologously expressed in human embryonic kidney cells.
Kir6.1 subunit is one of the pore-forming components of K(ATP) channel complex. The endogenous modulation of Kir6.1 subunit function has been largely unknown. Whether acetylcholine modulated the function of Kir6.1 subunit stably expressed in human embryonic kidney (HEK-293) cells was examined in the present study using the whole-cell patch-clamp technique. Acetylcholine from 1-100 microM concentration-dependently stimulated the heteologously expressed and PNU-37883A sensitive Kir6.1 channels (p<0.05). Co-expression of sulphonylurea receptor 1 subunit with Kir6.1 significantly inhibited the stimulatory effect of acetylcholine on K(ATP) currents. Pretreatment of the transfected HEK-293 cells with atropine, alpha-bungarotoxin, mecamylamine, prazocine, propranolol, or dihydro-beta-erythroidine hydrobromide did not alter the stimulatory effect of acetylcholine on Kir6.1 currents. When intracellular ATP was increased from 0.3 mM to 5 mM, acetylcholine at 10 microM still exhibited its stimulatory effect (-16.4+/-2.3 to -25.5+/-3.8 pA/pF, n=8, p<0.05). In conclusion, we have demonstrated an excitatory effect of acetylcholine on Kir6.1 channels, which is mediated neither by an acetylcholine receptor-dependent mechanism, nor by alteration in ATP metabolism.
Hanna
Salma Toma
ST
Department of Physiology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
Cao
Kun
K
Wang
Rui
R
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology*; D000109:Acetylcholine / Q000494:pharmacology*; D000218:Adamantane / Q000031:analogs & derivatives* / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D002038:Bungarotoxins / Q000494:pharmacology; D002460:Cell Line; D004079:Dihydro-beta-Erythroidine / Q000494:pharmacology; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D006801:Humans; D054086:KATP Channels; D008464:Mecamylamine / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009025:Morpholines / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000502:physiology; D014162:Transfection
D018528:ATP-Binding Cassette Transporters; D002038:Bungarotoxins; D054086:KATP Channels; D009025:Morpholines; D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists; D024661:Potassium Channels, Inwardly Rectifying; D011978:Receptors, Nicotinic; C092520:uK-ATP-1 potassium channel; D004079:Dihydro-beta-Erythroidine; D001464:Barium; D004246:Dimethylphenylpiperazinium Iodide; C082658:U 37883A; D008464:Mecamylamine; D001285:Atropine; D000255:Adenosine Triphosphate; D000109:Acetylcholine; D000218:Adamantane