Does Thin Filament Compliance Diminish the Cross-Bridge Kinetics?
A Study in Rabbit Psoas Fibers Biophysical Journal, Volume 76, Issue 2, 1 February 1999, Pages 978-984 Gang Wang, Wei Ding and Masataka Kawai Abstract The effect of thin filament compliance on our ability to detect the cross-bridge kinetics was examined. Our experiment is based on the facts that in rabbit psoas the thin filament (1.12m) is longer than half the thick filament length (0.82m) and that the thick filament has a central bare zone (0.16m). Consequently, when sarcomere length is increased from 2.1 to 2.4m, the same number of cross-bridges is involved in force generation but extra series compliance is introduced in the I-band. Three apparent rate constants (2a, 2b, and 2c) were characterized by sinusoidal analysis at pCa 4.66. Our results demonstrate that 2a and 2b increased 13–16% when sarcomere length was increased from 2.0 to 2.5m, and 2c decreased slightly (9%). This slight decrease can be explained by compression of the lattice spacing. These observations are at variance w
