Adaptation of the skeletal muscle calcium-release mechanism to weight-bearing condition
| Autor: | C. W. Ward, Susan C. Kandarian, David G. Peters, Jay H. Williams, Terence G. Favero |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
medicine.medical_specialty
Fura-2 Calcium Channels L-Type Physiology Blotting Western chemistry.chemical_element Alpha (ethology) Muscle Proteins Calcium Weight-Bearing chemistry.chemical_compound Internal medicine medicine Animals Rats Wistar Muscle Skeletal Ryanodine receptor Dihydropyridine Skeletal muscle Ryanodine Receptor Calcium Release Channel Cell Biology Adaptation Physiological Rats Dissociation constant Muscular Atrophy Sarcoplasmic Reticulum Endocrinology medicine.anatomical_structure Muscle Fibers Slow-Twitch chemistry Muscle Fibers Fast-Twitch Female Calcium Channels medicine.symptom medicine.drug Muscle contraction |
| Zdroj: | The American journal of physiology. 270(6 Pt 1) |
| ISSN: | 0002-9513 |
| Popis: | In the present study, we examined whether weight-bearing condition can regulate the sarcoplasmic reticulum (SR) Ca(2+)-release mechanism. Measurements of alpha 1-subunit dihydropyridine (alpha 1-DHP) and ryanodine receptor levels were made in hypertrophied fast-twitch plantaris muscles 5 wk after surgical removal of synergist muscles (increased weight bearing) and in atrophied slowtwitch soleus muscles (14 days of non-weight bearing) of the rat. Rates of AgNO3-induced SR Ca2+ release were measured with fura 2 as the Ca2+ indicator and pyrophosphate as the precipitating ion during vesicular Ca2+ loading. Ca(2+)-release rates were 38, 49, and 58% lower in vesicles from hypertrophied vs. control muscles at AgNO3 concentrations of 0.05, 0.5, and 5 microM, respectively (control = 18.2 +/- 1.4 microM.mg-1. min-1). Western blots showed no differences in the relative expression of alpha 1-DHP or ryanodine receptor when IIID5 (monoclonal) or GP3 (polyclonal) antibodies were used. There was also no difference in ryanodine (10 nM) binding in Ca(2+)-incubated SR vesicles from hypertrophied muscles, suggesting no difference in the number of channels. In contrast, expression of alpha 1-DHP and ryanodine receptors was increased by 144 and 157% in non-weight-bearing soleus muscles, respectively. Scatchard analysis of DHP binding showed a 40% increase in maximum binding capacity and no change in the dissociation constant with non-weight-bearing muscles. The direction of modification of the SR Ca(2+)-release mechanism is opposite with increased and decreased weight bearing, but the mechanism by which this is achieved appears to be different. |
| Databáze: | OpenAIRE |
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