QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

Help viewing high resolution images Return to article

Fig. 4. Ca²⁺ sensitivity of steady-state force development in transgenic papillary muscle fibers. A bundle of approximately three to five fibers isolated from glycerinated mouse papillary muscle fibers was attached by tweezer clips to a force transducer and placed in a 1 ml cuvette. After the initial steady-state force was measured in pCa 4 solution, the fiber bundles were exposed to solutions of increasing Ca²⁺ concentrations (from pCa 8 to pCa 4). Measurements were performed for control, Non-Tg fibers as well as for Tg-WT, Tg-E22K L2 and Tg-E22K L 4 fibers. (A) The force-pCa relationship for Non-Tg, Tg-WT, Tg-E22K L2 and Tg-E22K L4 mouse papillary muscle fibers. Significant differences in the pCa₅₀ values of the Ca²⁺ sensitivity of steady-state force were observed between Non-Tg (n=14) or Tg-WT (n=10) and two lines of Tg-E22K, line 2 (L2) (n=7) and line 4 (L4) (n=12) (P0.001). The largest difference of the pCa₅₀=0.12 was observed between Tg-WT and Tg-E22K L4 fibers (P<0.001). The steepness of the curves was lower for the mutant fibers and the respective n_H values were: 2.23±0.06, 2.44±0.08, 1.95±0.09 and 2.07±0.06 for Non-Tg, Tg-WT, Tg-E22K L2 and Tg-E22K L4 fibers. (B) The pCa₅₀ values for the force-pCa relationships of Non-Tg, Tg-WT, Tg-E22K L2 and Tg-E22K L4 mouse papillary muscle fibers. The Ca²⁺ sensitivity in Tg-E22K L2 (pCa₅₀=5.62±0.02, n=7) and L4 (pCa₅₀=5.65±0.01, n=12) fibers was increased compared with Non-Tg (pCa₅₀=5.54±0.01, n=14) or Tg-WT (pCa₅₀=5.53±0.01, n=10) fibers. As indicated, the differences were statistically significant (P0.001). Data are expressed as the average of n experiments ± s.e.m.

Return to article