Papel de las especies reactivas de oxígeno en la función endotelial renal y en la disfunción endotelial asociada a la obesidad

Además de su papel en la patogénesis de la enfermedad vascular, las especies reactivas de oxígeno (ROS) pueden actuar como moléculas de señalización fisiológica en la pared vascular, y ROS como el H2O2 están implicadas en las respuestas relajantes mediadas por la hiperpolarización derivada del endotelio (EDH) de arteriolas coronarias y mesentéricas, donde se libera en respuesta al flujo o a agonistas (Matoba et al., 2000; Matoba et al., 2003). El papel de las ROS en la función vascular renal ha sido investigado en el contexto perjudicial de la generación de ROS derivadas de NADPH oxidasa y mitocondria en diabetes y enfermedad renal asociada a obesidad (Sharma, 2015). Una fracción sustancial de la vasodilatación dependiente del endotelio de arterias renales está mediada por el factor relajante no-óxido nítrico (NO), no-prostanoide liberado por el endotelio (Büssemaker et al., 2003), cuya naturaleza aún se desconoce. La obesidad es un problema mundial de salud pública cuya prevalencia continúa aumentando en la actualidad, asociada con el desarrollo de la resistencia a la insulina, hipertensión, dislipidemia y diabetes tipo 2, conocidos en su conjunto como síndrome metabólico. La obesidad y el síndrome metabólico aumentan el riesgo de complicaciones diabéticas como la nefropatía y la enfermedad renal crónica (ERC). Sin embargo, estudios epidemiológicos recientes sugieren que la ERC puede desarrollarse en individuos obesos no diabéticos, y la obesidad representa un factor de riesgo de ERC independiente de la diabetes, la hipertensión y otras comorbilidades (De Vries et al., 2014)..

Implementación de un sistema b-learning en la enseñanza práctica de Fisiopatología

Fac. de FarmaciaFALSEsubmitte

Differential contribution of renal cytochrome P450 enzymes to kidney endothelial dysfunction and vascular oxidative stress in obesity

Arachidonic acid (AA)-derived cytochrome P450 (CYP) derivatives, epoxyeicosatrienoic acids (EETs) and 20-hidroxyeicosatetranoic acid (20-HETE), play a key role in kidney tubular and vascular functions and blood pressure. Altered metabolism of CYP epoxygenases and CYP hydroxylases has differentially been involved in the pathogenesis of metabolic disease-associated vascular complications, although the mechanisms responsible for the vascular injury are unclear. The present study aimed to assess whether obesity-induced changes in CYP enzymes may contribute to oxidative stress and endothelial dysfunction in kidney preglomerular arteries. Endothelial function and reactive oxygen species (ROS) production were assessed in interlobar arteries of obese Zucker rats (OZR) and their lean counterparts lean Zucker rats (LZR) and the effects of CYP2C and CYP4A inhibitors sulfaphenazole and HET0016, respectively, were examined on the endothelium-dependent relaxations and O2 − and H2O2 levels of preglomerular arteries. Non-nitric oxide (NO) non-prostanoid endothelium-derived hyperpolarization (EDH)-type responses were preserved but resistant to the CYP epoxygenase blocker sulfaphenazole in OZR in contrast to those in LZR. Sulfaphenazole did not further inhibit reduced arterial H2O2 levels, and CYP2C11/CYP2C23 enzymes were downregulated in intrarenal arteries from OZR. Renal EDH-mediated relaxations were preserved in obese rats by the enhanced activity and expression of endothelial calcium-activated potassium channels (KCa). CYP4A blockade restored impaired NO-mediated dilatation and inhibited augmented O2 − production in kidney arteries from OZR. The current data demonstrate that both decreased endothelial CYP2C11/ CYP2C23-derived vasodilator H2O2 and augmented CYP4A-derived 20-HETE contribute to endothelial dysfunction and vascular oxidative stress in obesity. CYP4A inhibitors ameliorate arterial oxidative stress and restore endothelial function which suggests its therapeutic potential for the vascular complications of obesity-associated kidney injury

Activation of AMP kinase ameliorates kidney vascular dysfunction, oxidative stress and inflammation in rodent models of obesity

Background and Purpose Obesity is a risk factor for the development of chronic kidney disease independent of diabetes, hypertension and other co-morbidities. Obesity-associated nephropathy is linked to dysregulation of the cell energy sensor AMP-activated protein kinase (AMPK). We aimed here to assess whether impairment of AMPK activity may cause renal arterial dysfunction in obesity and to evaluate the therapeutic potential of activating renal AMPK. Experimental Approach Effects of the AMPK activator A769662 were assessed on intrarenal arteries isolated from ob/ob mice and obese Zucker rats and then mounted in microvascular myographs. Superoxide and hydrogen peroxide production were measured by chemiluminescence and fluorescence, respectively, and protein expression was analysed by western blotting. Key Results Endothelium-dependent vasodilation and PI3K/Akt/eNOS pathway were impaired in preglomerular arteries from genetically obese rats and mice, along with impaired arterial AMPK activity and blunted relaxations induced by the AMPK activator A769662. Acute ex vivo exposure to A769662 restored endothelial function and enhanced activity of PI3K/Akt/eNOS pathway in obese rats, whereas in vivo treatment with A769662 improved metabolic state and ameliorated endothelial dysfunction, reduced inflammatory markers and vascular oxidative stress in renal arteries and restored redox balance in renal cortex of obese mice. Conclusion and Implications These results demonstrate that AMPK dysregulation underlies obesity-associated kidney vascular dysfunction and activation of AMPK improves metabolic state, protects renal endothelial function and exerts potent vascular antioxidant and anti-inflammatory effects. The beneficial effects of vascular AMPK activation might represent a promising therapeutic approach to the treatment of obesity-related kidney injury

Impacto de la implementación del aprendizaje basado en problemas en combinación con las prácticas de laboratorio clínico y virtual de Fisiopatología para el desarrollo de competencias profesionales

Sección Deptal. de Fisiología (Farmacia)Fac. de FarmaciaFALSEsubmitte

Implementación del aprendizaje basado en problemas (ABP) en la enseñanza práctica de la fisiología del sistema digestivo

Sección Deptal. de Fisiología (Farmacia)Fac. de FarmaciaFALSEsubmitte

Adaptación a un entorno semipresencial de una nueva herramienta mixta del aprendizaje basado en problemas en combinación con las prácticas de laboratorio clínico a la nueva asignatura Bases Anatómicas y Fisiología del Cuerpo Humano

Sección Deptal. de Fisiología (Farmacia)Fac. de FarmaciaFALSEsubmitte

Hydrogen peroxide activates store-operated Ca2+ entry in coronary arteries.

BACKGROUND AND PURPOSE Abnormal Ca2+ metabolism has been involved in the pathogenesis of vascular dysfunction associated with oxidative stress. Here, we have investigated the actions of H2O2 on store-operated Ca2+ (SOC) entry in coronary arteries and assessed whether it is impaired in arteries from a rat model of metabolic syndrome. EXPERIMENTAL APPROACH Simultaneous measurements of intracellular Ca2+ concentration and contractile responses were made in coronary arteries from Wistar and obese Zucker rats, mounted in microvascular myographs, and the effects of H2O2 were assessed. KEY RESULTS H2O2 raised intracellular Ca2+ concentrations, accompanied by simultaneous vasoconstriction that was markedly reduced in a Ca2+-free medium. Upon Ca2+ re-addition, a nifedipine-resistant sustained Ca2+ entry, not coupled to contraction, was obtained in endothelium-denuded coronary arteries. The effect of H2O2 on this voltage-independent Ca2+ influx was concentration dependent, and high micromolar H2O2 concentrations were inhibitory and reduced SOC entry evoked by inhibition of the sarcoplasmic reticulum ATPase (SERCA). H2O2-induced increases in Fura signals were mimicked by Ba2+ and reduced by heparin, Gd3+ ions and by Pyr6, a selective inhibitor of the Orai1-mediated Ca2+ entry. In coronary arteries from obese Zucker rats, intracellular Ca2+ mobilization and SOC entry activated by acute exposure to H2O2 were augmented and associated with local oxidative stress. CONCLUSION AND IMPLICATIONS H2O2 exerted dual concentration-dependent stimulatory/inhibitory effects on store-operated, IP3 receptor-mediated and Orai1-mediated Ca2+ entry, not coupled to vasoconstriction in coronary vascular smooth muscle. SOC entry activated by H2O2 was enhanced and associated with vascular oxidative stress in coronary arteries in metabolic syndrome.MINECODepto. de FisiologíaFac. de FarmaciaTRUEpu

COX-2 is involved in vascular oxidative stress and endothelial dysfunction of renal interlobar arteries from obese Zucker rats

Obesity is related to vascular dysfunction through inflammation and oxidative stress and it has been identified as a risk factor for chronic renal disease. In the present study, we assessed the specific relationships among reactive oxygen species (ROS), cyclooxygenase2 (COX-2), and endothelial dysfunction in renal interlobar arteries from a genetic model of obesity/insulin resistance, the obese Zucker rats (OZR). Relaxations to acetylcholine(ACh) were significantly reduced in renal arteries from OZR compared to their counterpart, the lean Zucker rat (LZR), suggesting endothelial dysfunction. Blockade of COX with indomethacin and with the selective blocker of COX-2 restored the relaxations to ACh in obese rats. Selective blockade of the TXA2/PGH2 (TP) receptor enhanced ACh relaxations only in OZR, while inhibition of the prostacyclin (PGI2) receptor (IP) enhanced basal tone and inhibited ACh vasodilator responses only in LZR. Basal production of superoxide was increased in arteries of OZR and involved NADPH and xanthine oxidase activation and NOS uncoupling. Under conditions of NOS blockade, ACh induced vasoconstriction and increased ROS generation that were augmented in arteries from OZRandbluntedbyCOX-2 inhibition and by the ROS scavenger tempol. Hydrogen peroxide (H2O2) evoked both endothelium-and vascular smooth muscle (VSM)-dependent contractions, as well as ROS generation that was reduced by COX-2 inhibition.In addition, COX-2 expression was enhanced in both VSM and endothelium of renal arteries from OZR. These results suggest that increased COX-2-dependent vasoconstriction contributes to renal endothelial dysfunction through enhanced (ROS) generation in obesity.COX-2 activity is in turn upregulated by ROS.Ministerio de Economía, Comercio y Empresa (MINECO)Depto. de FisiologíaDepto. de Anatomía y EmbriologíaFac. de FarmaciaFac. de VeterinariaTRUEpu