cGMP analogues reduced force of contraction in cardiac muscle from wild-type mice but not from cGKI-null mutants, demonstrating that cGKI mediates the negative inotropic effect of cGMP.
To study the role of cGMP-dependent protein kinase I (cGKI) for cardiac contractility, force of contraction (F(c)) was studied in electrically driven heart muscle from wild-type (WT) mice and from conventional and conditional cGKI knockout mice. Both 8-Br-cGMP and 8-pCPT-cGMP reduced Fc in cardiac muscle from juvenile WT but not from juvenile cGKI-null mutants. Similarly, the cGMP analogues reduced F(c) in forskolin-stimulated ventricular muscle from WT mice but not from cGKI-null mutants. In contrast, carbachol reduced F(c) in both groups of animals. 8-Br-cGMP reduced F(c) also in heart muscle from adult WT mice but not from adult cardiomyocyte-specific cGKI-knockout mice. These results demonstrate that cGKI mediates the negative inotropic effect of cGMP in the myocardium of juvenile and adult mice.
Wegener et al. (Fri,) conducted a other in Cardiac contractility. cGMP analogues (8-Br-cGMP and 8-pCPT-cGMP) vs. cGKI-null mutants was evaluated on Force of contraction (F(c)). cGMP analogues reduced force of contraction in cardiac muscle from wild-type mice but not from cGKI-null mutants, demonstrating that cGKI mediates the negative inotropic effect of cGMP.