Extraction of MyBP-C for 4 hours from rat cardiac trabeculae decreased maximum Ca-activated force and disordered myosin heads, which was reversible upon re-incubation with MyBP-C.
Does extraction of MyBP-C alter force production and thick filament structure in rat cardiac trabeculae?
Prolonged extraction of MyBP-C reversibly decreases maximum calcium-activated force and alters myosin head orientation, highlighting its role in cardiac contractility.
Human hearts with reduced or mutant myosin binding protein C (MyBP-C) undergo hypertrophy and dilation, suggesting that reduction or alteration of MyBP-C interferes with normal contraction. Extraction of 60-70% of MyBP-C over 1 h from a mechanically disrupted cardiac myocyte has been shown to increase Ca sensitivity but does not appear to impair development of maximum Ca-activated force (Fmax). To determine whether loss of MyBP-C over a longer period of time will decrease force development in a reversible manner, MyBP-C has been extracted from chemically skinned rat cardiac trabeculae for 1-4 h, and force production, Ca sensitivity, and thick filament structure were measured. Although extraction of MyBP-C for 1 h did not alter Fmax, after 4 h, myosin heads became disordered and Fmax decreased. At this point, incubation of the trabeculae with rat cardiac MyBP-C in a relaxing solution reversed the decline in Fmax and most of the change in order of myosin heads. Extraction of MyBP-C appears to produce a change in the orientation of myosin heads that is associated with a decreased ability of the contractile system to develop force.
Kulikovskaya et al. (Fri,) conducted a other in MyBP-C extraction in rat cardiac trabeculae. Extraction of MyBP-C vs. Baseline / Re-incubation with rat cardiac MyBP-C was evaluated on Force production (Fmax), Ca sensitivity, and thick filament structure. Extraction of MyBP-C for 4 hours from rat cardiac trabeculae decreased maximum Ca-activated force and disordered myosin heads, which was reversible upon re-incubation with MyBP-C.