What We Know and Do Not Know about Sex and Cardiac Disease

Figure 1

Relationship between Ca²⁺-sensitivity, length, and tension to the pressure-volume relationship. The sensitivity of cardiac myofilaments to Ca²⁺ indicates the contractile state of the cardiac muscle cell. The relationship between Ca²⁺ and tension is illustrated in the bottom panel labeled Ca²⁺-sensitivity of tension. There exists a unique Ca²⁺-sensitivity of tension relationship at each length (SL: sarcomere length) and these relationships can be used to create the Length-tension relationship (upper left panel) as indicated by the arrows. The Length-tension relationship can alternatively be called the end-systolic tension-length relationship (ESTLR) and is the underlying cellular mechanism of the end-systolic pressure-volume relationship (ESPVR; upper right panel).