Localization and function of ATP-sensitive potassium channels in human skeletal muscle.
The present study investigated the localization of ATP-sensitive K+ (KATP) channels in human skeletal muscle and the functional importance of these channels for human muscle K+ distribution at rest and during muscle activity. Membrane fractionation based on the giant vesicle technique or the sucrose-gradient technique in combination with Western blotting demonstrated that the KATP channels are mainly located in the sarcolemma. This localization was confirmed by immunohistochemical measurements. With the microdialysis technique, it was demonstrated that local application of the KATP channel inhibitor glibenclamide reduced (P < 0.05) interstitial K+ at rest from approximately 4.5 to 4.0 mM, whereas the concentration in the control leg remained constant. Glibenclamide had no effect on the interstitial K+ accumulation during knee-extensor exercise at a power output of 60 W. In contrast to in vitro conditions, the present study demonstrated that under in vivo conditions the KATP channels are active at rest and contribute to the accumulation of interstitial K+.
Nielsen
Jens Jung
JJ
Copenhagen Muscle Research Centre, August Krogh Institute, and Institute of Exercise and Sports Sciences, Copenhagen, Denmark.
Kristensen
Michael
M
Hellsten
Ylva
Y
Bangsbo
Jens
J
Juel
Carsten
C
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000328:Adult; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D015640:Ion Channel Gating / Q000187:drug effects; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D015221:Potassium Channels; D000255:Adenosine Triphosphate; D011188:Potassium; D005905:Glyburide