title: Sarcolemmal ATP-sensitive potassium channels modulate skeletal muscle function under low-intensity workloads.
abstract: ATP-sensitive potassium (KATP) channels have the unique ability to adjust membrane excitability and functions in accordance with the metabolic status of the cell. Skeletal muscles are primary sites of activity-related energy consumption and have KATP channels expressed in very high density. Previously, we demonstrated that transgenic mice with skeletal muscle-specific disruption of KATP channel function consume more energy than wild-type littermates. However, how KATP channel activation modulates skeletal muscle resting and action potentials under physiological conditions, particularly low-intensity workloads, and how this can be translated to muscle energy expenditure are yet to be determined. Here, we developed a technique that allows evaluation of skeletal muscle excitability in situ, with minimal disruption of the physiological environment. Isometric twitching of the tibialis anterior muscle at 1 Hz was used as a model of low-intensity physical activity in mice with normal and genetically disrupted KATP channel function. This workload was sufficient to induce KATP channel opening, resulting in membrane hyperpolarization as well as reduction in action potential overshoot and duration. Loss of KATP channel function resulted in increased calcium release and aggravated activity-induced heat production. Thus, this study identifies low-intensity workload as a trigger for opening skeletal muscle KATP channels and establishes that this coupling is important for regulation of myocyte function and thermogenesis. These mechanisms may provide a foundation for novel strategies to combat metabolic derangements when energy conservation or dissipation is required.
authors.affiliation: Department of Internal Medicine and 2 Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhu
authors.forename: Ana
authors.initials: A
authors.lastname: Sierra
authors.forename: Colin M-L
authors.initials: CM
authors.lastname: Burnett
authors.forename: Biyi
authors.initials: B
authors.lastname: Chen
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Subbotina
authors.forename: Siva Rama Krishna
authors.initials: SR
authors.lastname: Koganti
authors.forename: Zhan
authors.initials: Z
authors.lastname: Gao
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Wu
authors.forename: Mark E
authors.initials: ME
authors.lastname: Anderson
authors.forename: Long-Sheng
authors.initials: LS
authors.lastname: Song
authors.forename: David J
authors.initials: DJ
authors.lastname: Goldhamer
authors.forename: William A
authors.initials: WA
authors.lastname: Coetzee
authors.forename: Denice M
authors.initials: DM
authors.lastname: Hodgson-Zingman
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Zingman
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D007537:Isometric Contraction; D054086:KATP Channels / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D009213:Myography / Q000295:instrumentation / Q000379:methods; D005082:Physical Exertion; D012508:Sarcolemma / Q000378:metabolism / Q000502:physiology
chemical_list: D054086:KATP Channels; C092520:uK-ATP-1 potassium channel; D002118:Calcium