Activation of atrial muscarinic K+ channels by low concentrations of beta gamma subunits of rat brain G protein.
Effects of G protein beta gamma subunits from rat brain on cardiac K+ channel was examined in single atrial cells of guinea-pig, using patch clamp techniques. We found that 10 pM concentration of rat brain beta gamma subunits preparation could activate the atrial muscarine receptor-gated K+ channel (IK.ACh). Neither the detergent, CHAPS, used to suspend beta gamma nor the boiled beta gamma preparation activated IK.ACh. Furthermore, preincubation of beta gamma subunits preparation in Mg2+-free solution, which easily inactivated alpha-GTP-gamma S, did not affect beta gamma-activation of IK.ACh. We concluded, therefore, that beta gamma subunits themselves can activate IK.ACh.
Kurachi
Y
Y
2nd Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Ito
H
H
Sugimoto
T
T
Katada
T
T
Ui
M
M
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D019204:GTP-Binding Proteins / Q000494:pharmacology*; D006168:Guinea Pigs; D006325:Heart Atria / Q000166:cytology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*
D015221:Potassium Channels; D011976:Receptors, Muscarinic; D019204:GTP-Binding Proteins; D000109:Acetylcholine