Autor: | P. M. Orkand, C. Zuazaga, G. Ortiz, J. Monterrubio |
---|---|
Rok vydání: | 2002 |
Předmět: |
Membrane potential
medicine.medical_specialty Voltage-dependent calcium channel Physiology Endoplasmic reticulum Cardiac muscle Skeletal muscle Cardiac action potential Cell Biology Biology Biochemistry Electrophysiology medicine.anatomical_structure Endocrinology Internal medicine medicine Biophysics Myocyte |
Zdroj: | Journal of Muscle Research and Cell Motility. 23:167-174 |
ISSN: | 0142-4319 |
Popis: | Ca2+-induced Ca2+ release (CICR) in the superficial abdominal flexor muscle of the crustacean Atya lanipes appears to be mediated by a local control mechanism similar to that of vertebrate cardiac muscle, but with an unusually high gain. Thus, Ca2+ influx increases sufficiently the local concentration of Ca2+ in the immediate vicinity of the sarcoplasmic reticulum Ca2+ release channels to trigger the highly amplified release of Ca2+ required for contraction, but is too low to generate a macroscopic inward current (i.e., the Ca2+ channels are silent). To determine the localization of the silent Ca2+ channels, the mechanical, electrophysiological and ultrastructural properties of the muscle were examined before and after formamide treatment, a procedure that produces the disruption of transverse tubules of striated muscle. We found that tubular disruption decreased tension generation by about 90%; reduced inward current (measured as V max, the maximum rate of rise of Sr2+ action potentials) by about 80%; and decreased membrane capacitance by about 77%. The results suggest that ca. 80% of the silent Ca2+ channels are located in the tubular system. Thus, these studies provide further evidence to support the local control mechanism of CICR in crustacean skeletal muscle. |
Databáze: | OpenAIRE |
Externí odkaz: |