Free calcium at rest during "catch" in single smooth muscle cells |
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| Authors: | N Ishii A W Simpson C C Ashley |
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| Institution: | Zoological Institute, Faculty of Science, University of Tokyo, Japan. |
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| Abstract: | Tension and intracellular free calcium concentration ( Ca2+]i) were measured simultaneously in single smooth muscle cells isolated from the anterior byssus retractor muscle (ABRM) of Mytilus edulis that were loaded with the fluorescent Ca2+ indicator fura-2. Electrical stimulation evoked a transient elevation of Ca2+]i associated with a "catch" contraction. During the catch state, however, Ca2+]i was effectively at its resting level and was unaffected by 5-hydroxytryptamine, which induced a rapid relaxation from catch. The results indicate that a maintained high Ca2+]i is not required for the maintenance of catch tension in intact ABRM and that there was no significant change in Ca2+]i upon abolition of catch. |
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