Figure 5.

Single myocytes exchange with 50% pseudo-phosphorylated TnI exhibit half the phosphorylation mediated sensitivity change. Average normalized force-pCa measurements of Tn exchanged single cardiac myocytes. (A) The decrease in Ca²⁺-sensitive force development of myocytes exchanged with Tn containing 50% WT and 50% Ser-23/24 pseudo-phosphorylated TnI (Tn WT+S23/24D: black square, dashed line; n = 7) is half that of myocytes exchanged with Tn containing Ser-23/24 pseudo-phosphorylated TnI (Tn S23/24D: gray triangle, dashed line; n = 7) compared to WT (Tn WT: black circle, solid line; n = 8) exchange. (B) The increase in Ca²⁺-sensitive force development of myocytes exchanged with Tn containing 50% WT and 50% Ser-150 pseudo-phosphorylated TnI (Tn WT+S150D: black square, dashed line; n = 9) is half that of myocytes exchanged with Tn containing Ser-150 pseudo-phosphorylated TnI (Tn S150D: gray triangle, dashed line; n = 7) compared to Tn WT exchange. (C) Comparison of pCa₅₀. ^*p < 0.05 vs. WT Tn.