Long-term depolarization regulates the alpha1s, subunit of skeletal muscle Ca2+ channels and the amplitude of L-type Ca2+ currents
| Autor: | Jorge A. Sánchez, María C. García, José M. Farías, Rubén García, Juan Escamilla |
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| Rok vydání: | 2001 |
| Předmět: |
Patch-Clamp Techniques
Calcium Channels L-Type Nifedipine Ranidae Physiology Protein subunit Clinical Biochemistry Blotting Western Membrane Potentials Western blot Physiology (medical) medicine Animals Channel blocker Muscle Skeletal Fluorescent Dyes Aniline Compounds medicine.diagnostic_test Chemistry Electric Conductivity Skeletal muscle Depolarization Hyperpolarization (biology) Calcium Channel Blockers Electrophysiology Kinetics medicine.anatomical_structure Spectrometry Fluorescence Biochemistry Xanthenes Biophysics Calcium medicine.drug |
| Zdroj: | Pflugers Archiv : European journal of physiology. 442(6) |
| ISSN: | 0031-6768 |
| Popis: | The effects of long-term depolarization on the level of alpha1s and on L-type Ca2+ currents of skeletal muscle were investigated. Long-term depolarization (14 h) caused a 50% decrease of alpha1s, revealed with the Western blot technique. This decline was prevented by preincubation with the Ca2+ channel blocker nifedipine. Electrophysiological experiments using the voltage-clamp technique were performed to measure the actions of long-term depolarization on Ca2+ currents and charge movement. A progressive decline in the amplitude of the Ca2+ currents by depolarizations lasting 0.5-14 h was observed. Similar to Western blot results, the fall in current amplitude was prevented by nifedipine, and it depended on external Ca2+. The nonlinear charge mobilized by step pulses was also significantly reduced (50%) by long-term depolarization. It is suggested that alpha1s subunit is down-regulated by long-term depolarization by a very stringent mechanism and that, in this process, Ca2+ ions permeating through L-type channels play a key role. A new role for the L-type Ca2+ current in skeletal muscle fibers in which the channels are self-regulated is proposed. |
| Databáze: | OpenAIRE |
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