Fig. 4.

Mechanical properties of sln^−/− atria. (A) Effect of extracellular Ca²⁺ and ISO on the isometric force generation in isolated left atria from WT and sln^−/− mice. #, isometric force generation in sln^−/− atria (at 2 mM Ca²⁺) was significantly different from WT atria at all Ca²⁺ concentrations; *, isometric force generation in WT atria at 6 mM Ca²⁺ and ISO stimulation was significantly different from the basal contraction at 2 mM Ca²⁺ (P < 0.05). NS, not significant. Time taken for 50% relaxation (RT₅₀) (B) and 90% relaxation (RT₉₀) (C) was significantly faster in the sln^−/− atria. *, P < 0.05 (significant difference between WT and sln^−/− groups). n = 5.