TY - JOUR
T1 - Role of calcium in the regulation of acetylcholine receptor synthesis in cultured muscle cells
AU - Birnbaum, Miriam
AU - Reis, Moshe A.
AU - Shainberg, Asher
PY - 1980/5
Y1 - 1980/5
N2 - 1. Embryonic muscles differentiated in vitro were used to study the effects of intracellular Ca2+ ([Ca2+]i) variations on the amount of acetylcholine receptors ([AChR]) in the cell membrane. 2. Increased Ca2+ concentration in the growth medium ([Ca2+]o) caused a marked elevation of AChR levels, apparently through de novo synthesis. 3. Agents known to increase [Ca2+]i and its accumulation in the sarcoplasmic reticulum (SR), such as ionophore A23187, sodium dantrolene (DaNa), or high [Mg2+]o all enhanced α-bungarotoxin (α-BGT) binding after 48 h of treatment. 4. Electrical stimulation or caffeine, both affectors of SR calcium release, brought about a decrease in [AChR] probably by suppressing its synthesis. 5. The effects of simultaneous treatment with two AChR-inducing agents, namely, high [Ca2+]o in the presence of tetrodotoxin (TTX) or high [Mg2+]o were not additive, thus suggesting action via a common saturable mediator. 6. Intermediate AChR levels obtained following simultaneous treatments with opposing effects, e. g., electrical stimulation in the presence of high [Ca2+]o or DaNa, suggest contradictory actions on a common mediator. 7. All these observations indicate a strong correlation between SR calcium levels and [AChR] on myotubes; while calcium accumulation in the SR was followed by increased AChR synthesis, calcium release was accompanied by suppression of receptor synthesis.
AB - 1. Embryonic muscles differentiated in vitro were used to study the effects of intracellular Ca2+ ([Ca2+]i) variations on the amount of acetylcholine receptors ([AChR]) in the cell membrane. 2. Increased Ca2+ concentration in the growth medium ([Ca2+]o) caused a marked elevation of AChR levels, apparently through de novo synthesis. 3. Agents known to increase [Ca2+]i and its accumulation in the sarcoplasmic reticulum (SR), such as ionophore A23187, sodium dantrolene (DaNa), or high [Mg2+]o all enhanced α-bungarotoxin (α-BGT) binding after 48 h of treatment. 4. Electrical stimulation or caffeine, both affectors of SR calcium release, brought about a decrease in [AChR] probably by suppressing its synthesis. 5. The effects of simultaneous treatment with two AChR-inducing agents, namely, high [Ca2+]o in the presence of tetrodotoxin (TTX) or high [Mg2+]o were not additive, thus suggesting action via a common saturable mediator. 6. Intermediate AChR levels obtained following simultaneous treatments with opposing effects, e. g., electrical stimulation in the presence of high [Ca2+]o or DaNa, suggest contradictory actions on a common mediator. 7. All these observations indicate a strong correlation between SR calcium levels and [AChR] on myotubes; while calcium accumulation in the SR was followed by increased AChR synthesis, calcium release was accompanied by suppression of receptor synthesis.
KW - Acetylcholine receptor synthesis
KW - Intracellular calcium concentration
KW - Sarcoplasmic reticulum
KW - Skeletal muscle cultures
UR - http://www.scopus.com/inward/record.url?scp=0018829395&partnerID=8YFLogxK
U2 - 10.1007/bf00583913
DO - 10.1007/bf00583913
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C2 - 7191096
AN - SCOPUS:0018829395
SN - 0031-6768
VL - 385
SP - 37
EP - 43
JO - Pflugers Archiv European Journal of Physiology
JF - Pflugers Archiv European Journal of Physiology
IS - 1
ER -