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Depolarization accelerates the decay of K + contractures in rat skeletal muscle fibers
Author(s) -
Patterson Michael F.,
Mould Jorgen,
Dulhunty Angela F.
Publication year - 1996
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199608)19:8<1025::aid-mus10>3.0.co;2-w
Subject(s) - muscle contracture , contracture , depolarization , chemistry , extensor digitorum muscle , soleus muscle , contraction (grammar) , anatomy , biophysics , muscle contraction , skeletal muscle , medicine , surgery , biology
The experiments examine the effects of membrane potential on the time course of K + contractures in small bundles of rat soleus and extensor digitorum longus (EDL) muscle fibers. Control K + contractures were induced by exposure to a 200 mmol/L K + solution in polarized fibers with a resting membrane potential of −83 mV (3.5 mmol/L K + ), while test contractures were evoked with 200 mmol/L K + from −46 mV, after 5, 10, and 30 min in a 30 mmol/L K + conditioning solution. The decay times of the test K + contracture in depolarized fibers were faster than those of the control K + contracture in both soleus and EDL. A maximum reduction of 60% in the time for the contracture to decay from 90% to 10% was seen in soleus fibers after depolarizations lasting 10 min, while a reduction of 45% was seen in the decay time of EDL fibers after a 5‐min depolarizations. The amplitudes of the test contractures were 30% less than control after 5‐min and 10‐min depolarization and 50% less than control after 30 min. Analysis of the results suggests that the kinetics of excitation‐contraction coupling may be altered in damaged muscle fibers. © 1996 John Wiley & Sons, Inc.