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Gene Transfer of cGMP-Dependent Protein Kinase I Enhances the Antihypertrophic Effects of Nitric Oxide in Cardiomyocytes

2002; Lippincott Williams & Wilkins; Volume: 39; Issue: 1 Linguagem: Inglês

10.1161/hy1201.097292

1524-4563

Kai C. Wollert, Beate Fiedler, Stepan Gambaryan, Albert Smolenski, Jörg Heineke, Elke Butt, Christian Trautwein, Suzanne M. Lohmann, Helmut Drexler,

Ion channel regulation and function

NO acting through soluble guanylyl cyclase and cGMP formation is a negative regulator of cardiomyocyte hypertrophy. Downstream targets mediating the inhibitory effects of NO/cGMP on cardiomyocyte hypertrophy have not been elucidated. In addition to its antihypertrophic effects, NO promotes apoptosis in cardiomyocytes, presumably through cGMP-independent pathways. We investigated the role of cGMP-dependent protein kinase (PKG) in the antihypertrophic and proapoptotic effects of NO. Incubation of neonatal rat cardiomyocytes with the NO donor S -nitroso- N -acetyl- d , l -penicillamine (SNAP) (250 μmol/L) or the PKG-selective cGMP analog 8-pCPT–cGMP (500 μmol/L) activated endogenous PKG type I, as shown by the site-specific phosphorylation of vasodilator-stimulated phosphoprotein, a well-characterized PKG substrate. SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) modestly attenuated the hypertrophic response to α 1 -adrenergic stimulation with phenylephrine. Although a high concentration of SNAP (1000 μmol/L) promoted apoptosis in cardiomyocytes, as evidenced by the formation of histone-associated DNA fragments, antihypertrophic concentrations of SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) did not promote cell death. Because chronic activation downregulated endogenous PKG I, we explored whether gene transfer of PKG I would enhance the sensitivity of cardiomyocytes to the antihypertrophic effects of NO/cGMP. Indeed, after adenoviral overexpression of PKG Iβ, SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) completely suppressed the hypertrophic response to α 1 -adrenergic stimulation. As observed in noninfected cells, SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) did not promote apoptosis in cardiomyocytes overexpressing PKG Iβ. Moreover, overexpression of PKG Iβ did not enhance the proapoptotic effects of 1000 μmol/L SNAP, implying PKG-independent effects of NO on apoptosis. Endogenous PKG I mediates antihypertrophic but not proapoptotic effects of NO in a cell culture model of cardiomyocyte hypertrophy. Adenoviral gene transfer of PKG I selectively enhances the antihypertrophic effects of NO without increasing the susceptibility to apoptosis.