Publication Date:
1978-06-16
Description:
High concentrations (80 to 90 millimolar) of the calcium buffers EGTA and citrate (less than 10(-7) molar free calcium ion) reversibly block excitation-contraction coupling in intact frog skeletal fibers, but do not block caffeine-induced contractures. Solutions containing the same free calcium concentration but lower concentrations of calcium buffer (1 millimolar) do not block excitation-contraction coupling. These results suggest that excitation-contraction coupling requires the presence of calcium in a "protected" extracellular compartment, probably the transverse tubular network, and that calcium is actively transported into this compartment from the muscle cell cytoplasm.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barrett, N -- Barrett, E F -- New York, N.Y. -- Science. 1978 Jun 16;200(4347):1270-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/96524" target="_blank"〉PubMed〈/a〉
Keywords:
Action Potentials/drug effects
;
Animals
;
Anura
;
Biological Transport, Active
;
Calcium/*physiology
;
Citrates/pharmacology
;
Egtazic Acid/pharmacology
;
Extracellular Space/metabolism
;
In Vitro Techniques
;
*Muscle Contraction/drug effects
;
Muscles/*physiology
;
Rana pipiens
;
Sarcoplasmic Reticulum/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
