TY - JOUR A1 - Frantz, Stefan A1 - Klaiber, Michael A1 - Baba, Hideo A. A1 - Oberwinkler, Heinz A1 - Völker, Katharina A1 - Gaßner, Birgit A1 - Bayer, Barbara A1 - Abeßer, Marco A1 - Schuh, Kai A1 - Feil, Robert A1 - Hofmann, Franz A1 - Kuhn, Michaela T1 - Stress-dependent dilated cardiomyopathy in mice with cardiomyocyte-restricted inactivation of cyclic GMP-dependent protein kinase I JF - European Heart Journal N2 - Aims: Cardiac hypertrophy is a common and often lethal complication of arterial hypertension. Elevation of myocyte cyclic GMP levels by local actions of endogenous atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) or by pharmacological inhibition of phosphodiesterase-5 was shown to counter-regulate pathological hypertrophy. It was suggested that cGMP-dependent protein kinase I (cGKI) mediates this protective effect, although the role in vivo is under debate. Here, we investigated whether cGKI modulates myocyte growth and/or function in the intact organism. Methods and results: To circumvent the systemic phenotype associated with germline ablation of cGKI, we inactivated the murine cGKI gene selectively in cardiomyocytes by Cre/loxP-mediated recombination. Mice with cardiomyocyte-restricted cGKI deletion exhibited unaltered cardiac morphology and function under resting conditions. Also, cardiac hypertrophic and contractile responses to β-adrenoreceptor stimulation by isoprenaline (at 40 mg/kg/day during 1 week) were unaltered. However, angiotensin II (Ang II, at 1000 ng/kg/min for 2 weeks) or transverse aortic constriction (for 3 weeks) provoked dilated cardiomyopathy with marked deterioration of cardiac function. This was accompanied by diminished expression of the \([Ca^{2+}]_i\)-regulating proteins SERCA2a and phospholamban (PLB) and a reduction in PLB phosphorylation at Ser16, the specific target site for cGKI, resulting in altered myocyte \(Ca^{2+}_i\) homeostasis. In isolated adult myocytes, CNP, but not ANP, stimulated PLB phosphorylation, \(Ca^{2+}_i\)-handling, and contractility via cGKI. Conclusion: These results indicate that the loss of cGKI in cardiac myocytes compromises the hypertrophic program to pathological stimulation, rendering the heart more susceptible to dysfunction. In particular, cGKI mediates stimulatory effects of CNP on myocyte \(Ca^{2+}_i\) handling and contractility. KW - cyclic KW - GMPcGMP-dependent protein kinase I KW - cardiac hypertrophy KW - natriuretic peptide KW - Ca2+i handling Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134693 VL - 34 ER -