Table 2.

Stretch Activation Parameters of Skinned Fibers Isolated From WT and cMyBPC^−/− Hearts After Viral Treatment

	k_{df, S}⁻¹	k_{rel, S}⁻¹	P₂	P₃	P_df
WT (5)	23.59±1.23	271±21	0.04±0.01	0.10±0.01	0.06±0.01
cMyBPC^−/− (4)	35.49±1.40^*	470±20^*	−0.03±0.01^†	0.10±0.01	0.13±0.01^†
cMyBPC^−/−+LCMV (3)	34.96±1.92^*	443±32^*	−0.04±0.02^†	0.10±0.02	0.14±0.02^†
cMyBPC^−/−+LcMyBPC (21 days) (5)	24.94±1.79	280±27	0.04±0.02	0.11±0.01	0.07±0.02
cMyBPC^−/−+LcMyBPC (20 weeks) (3)	26.03±2.41	318±36	0.04±0.02	0.11±0.02	0.07±0.02

WT indicates wild-type; cMyBPC, cardiac myosin binding protein C; cMyBPC^−/−+LCMV, vehicle-treated cMyBPC^−/−; cMyBPC^−/−+LcMyBPC, LcMyBPC-treated cMyBPC^−/− 21 days or 20 weeks after gene transfer.

Data are mean±SE. Skinned ventricular fibers (20–25 per group) were isolated from 3 to 5 mice per group (indicated in parentheses). All data presented for each subgroup were collected from the number of mice indicated in the left column. Rate constants were calculated from force transients in response to stretches of 1% of muscle length at approximately half-maximal levels of activation. Stretch activation parameters are described in the online-only Data Supplement.

Significantly different from WT, P<0.001.

^†

Significantly different from WT, P<0.01.