RESUMO
cGMP is generated in endothelial cells after stimulation of soluble guanylyl cyclase (sGC) by nitric oxide (NO) or of particulate guanylyl cyclase (pGC) by natriuretic peptides (NP). We examined whether localized increases in cytosolic cGMP have distinct regulatory roles on the contraction induced by H2O2 treatment in human umbilical vein endothelial cells. cGMP concentrations and temporal dynamics were different upon NO stimulation of sGC or C-type NP (CNP) activation of pGC and did not correlate with their relaxing effects measured as planar cell surface area after H2O2 challenge. cGMP production due to sGC stimulation was always smaller and more brief than that induced by pGC stimulation with CNP, which was greater and remained elevated longer. The NO effects on cell relaxation were cGMP dependent because they were blocked by sGC inhibition with 1H-(1,2,4)Oxadiazolo(4,3-a)quinoxaline-1-one and mimicked by 8-Br-cGMP. An antagonist of the cGMP-dependent protein kinase type-I (PKG-I) also inhibited the NO-induced effects. The cell contraction induced by H2O2 produces myosin light chain (MLC) phosphorylation and NO prevented it completely, whereas CNP only produced a partial inhibition. Transfection with a dominant negative form of PKG type-I alpha completely reversed the NO-induced effects on MLC phosphorylation, whereas it only partially inhibited the effects due to CNP. Taken together, these results demonstrate that the NO/sGC/cGMP pathway induces endothelial cell relaxation in a more efficient manner than does CNP/pGC/cGMP pathway, an effect that might be related to a selective stimulation of PKG-1 alpha by NO-derived cGMP. Consequently, stimulated PKG-I alpha may phosphorylate important protein targets that are necessary to inhibit the endothelial contractile machinery activated by oxidative stress.
Assuntos
Endotélio Vascular/fisiologia , Guanilato Ciclase/metabolismo , Vasodilatação/fisiologia , Células Cultivadas , GMP Cíclico/farmacologia , GMP Cíclico/fisiologia , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Combinação de Medicamentos , Endotélio Vascular/citologia , Ativação Enzimática/fisiologia , Humanos , Peróxido de Hidrogênio/farmacologia , Isoenzimas/metabolismo , Peptídeo Natriurético Tipo C/metabolismo , Peptídeo Natriurético Tipo C/farmacologia , Óxido Nítrico/farmacologia , Óxido Nítrico/fisiologia , Oxidantes/farmacologia , Solubilidade , Vasoconstrição/efeitos dos fármacos , Vasodilatação/efeitos dos fármacosAssuntos
GMP Cíclico/fisiologia , Guanilato Ciclase/fisiologia , Sistemas do Segundo Mensageiro/fisiologia , Adenilil Ciclases/fisiologia , Animais , Fator Natriurético Atrial/fisiologia , AMP Cíclico/fisiologia , GMP Cíclico/biossíntese , Proteínas Quinases Dependentes de GMP Cíclico/fisiologia , Citosol/enzimologia , Proteínas de Ligação ao GTP/fisiologia , Humanos , Transporte de Íons/fisiologia , Isoenzimas/fisiologia , Rim/fisiologia , Mamíferos/metabolismo , Proteínas de Membrana/fisiologia , Modelos Biológicos , Natriurese/fisiologia , Óxido Nítrico/fisiologia , Óxido Nítrico Sintase/fisiologia , Especificidade de Órgãos , Diester Fosfórico Hidrolases/fisiologia , Homologia de Sequência de Aminoácidos , Transdução de Sinais/fisiologiaRESUMO
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