Figure 5. Ca²⁺-sensitivity of active force, and passive force in PDE5-TG and WT cardiac myocytes after chronic pressure overload.

(A) In the Ca²⁺-force relationship, the Ca²⁺-sensitivity of isometric force production represents the [Ca²⁺] (plotted as a function of pCa; pCa = −log₁₀[Ca²⁺]) evoking half-maximal force production (top panel). Ca²⁺-sensitivity did not differ between PDE5-TG and WT cardiac myocytes, and was reduced after pretreatment with PKG (bottom panel). (B) Passive forces were significantly greater in cardiac myocytes from PDE5-TG compared to WT cardiac myocytes. Pretreatment of cardiac myocytes with PKG significantly reduced the passive forces in both genotypes. *P<0.05; ^† P<0.05 vs without PKG.