Role of Ca2+ and cross-bridges in skeletal muscle thin filament activation probed with Ca2+ sensitizers

From: Biophysical Journal | Date: April 1, 1999| Author: | Copyright information

ABSTRACT Thin filament regulation of contraction is thought to involve the binding of two activating ligands: Ca^sup 2+^ and strongly bound cross-bridges. The specific cross-bridge states required to promote thin filament activation have not been identified. This study examines the relationship between cross-bridge cycling and thin filament activation by comparing the results of kinetic experiments using the Ca^sup 2+^ sensitizers caffeine and bepridil. In single skinned rat soleus fibers, 30 mM caffeine produced a leftward shift in the tension-pCa relation from 6.03 +/- 0.03 to 6.51 +/- 0.03 ...

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