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MECHANISM OF POTENTIATION OF CONTRACTION BY DEPOLARIZATION DURING ACTION POTENTIALS IN GUINEA‐PIG VENTRICULAR MUSCLE
Author(s) -
Terrar D. A.,
White E.
Publication year - 1989
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1989.sp003277
Subject(s) - long term potentiation , contraction (grammar) , caffeine , guinea pig , depolarization , calcium , biophysics , chemistry , muscle contraction , medicine , biology , biochemistry , receptor
Action potentials were recorded from guinea‐pig ventricular cells and contraction recorded by an optical technique. When the plateau of a single action potential was depolarized (by 70–120 pA applied 100 ms after the upstroke for 100 ms), contraction associated with the following normal action potential was potentiated. This potentiation was not seen in cells exposed to 10 mM‐caffeine. The observations are consistent with potentiation of subsequent contraction by increased loading of caffeine‐sensitive calcium stores, as a consequence of reduced Ca 2+ extrusion or possibly Ca 2+ entry via Na + −Ca 2+ exchange during a depolarized plateau.