PDE5A and cardiac hypertrophy: And, PKGI “β-rescue” mice with whole-body deletion of PKGI, in which the Iβ isoform was selectively reexpressed only in smooth muscle tissue, were reported to have no differences in cardiac hypertrophy in response to isopreterenol or to TAC, at a single duration after surgery.40 Conversely, pharmacologic approaches that limit cardiac remodeling, such as PDE5 inhibition,1 activate PKGI indirectly but lack specificity for PKGI activation, making interpretation of the specific role of PKGI difficult.