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Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Ionic movements mediated by monensin in frog skeletal muscle
1Catedra de Fisiologia con Biofisica, Facultad de Ciencias Medicas, Universidad Nacional de La Plata, Argentina.
Biochimica Et Biophysica Acta
|February 17, 1992
Summary
Monensin induces dose-dependent ion fluxes, including sodium (Na+), potassium (K+), and hydrogen (H+), in frog skeletal muscle fibers. These movements impact cellular ion balance and membrane potential.
Area of Science:
- Muscle Physiology
- Ion Transport Mechanisms
- Biophysical Chemistry
Background:
- Monensin is an ionophore known to transport monovalent cations.
- Understanding its effects on skeletal muscle is crucial for cell physiology.
- Ionic homeostasis is vital for muscle function.
Purpose of the Study:
- To investigate monensin-mediated ionic movements in frog skeletal muscle.
- To quantify the dose-dependent fluxes of Na+, K+, and H+ induced by monensin.
- To elucidate the net ionic exchanges and their contribution to cellular ion balance.
Main Methods:
- Studied ion fluxes in frog skeletal muscle fibers using varying monensin concentrations (2-40 microM).
- Measured unidirectional and net fluxes of Na+, K+, and H+ using radiolabeled tracers or electrochemical methods.
- Analyzed the composition of influx and efflux pathways.
Main Results:
- Monensin induced dose-dependent fluxes of Na+, K+, and H+ across the muscle membrane.
- Maximum ionic exchanges included Nai+/Nao+ (112 pmol cm-2 s-1), Nai+/Ho+ (30.7 pmol cm-2 s-1), Ki+/Nao+ (14.2 pmol cm-2 s-1), and Hi+/Nao+ (49 pmol cm-2 s-1).
- Maximum net fluxes were Na+ (inward) 32.5, K+ (outward) 14.2, and H+ (outward) 18.3 pmol cm-2 s-1.
Conclusions:
- Monensin significantly alters ion transport in skeletal muscle.
- The observed H+ efflux is partially counteracted by passive influx, influencing intracellular pH.
- Monensin-mediated fluxes contribute to changes in cellular ion concentrations and membrane potential.
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