Physiologic Basis and Pathophysiologic Implications of the Diastolic Properties of the Cardiac Muscle

Figure 2

Progressive increase in myocardial (a) and collagen-based stiffness (b) during physiologic cardiac growth as well as HF or HF-associated pathological conditions. The increase in myocardial stiffness can be paralleled by a concordant increase in the expression of the stiff titin isoform N2B (c) or by a compensatory increase in the expression of the compliant titin isoform N2BA (d). Relative hypophosphorylation of the stiff N2B titin also accounts for an increase in myocardial stiffness in HF, especially in HFNEF (e) (P-N2B: phosphorylated N2B; P-N2BA: phosphorylated N2BA).