Gentamicin-induced preconditioning of proximal tubular LLC-PK1 cells stimulates nitric oxide production but not the synthesis of heat shock protein

Nephrotoxicity is the main side effect of antibiotics such as gentamicin. Preconditioning has been reported to protect against injuries as ischemia/reperfusion. The objective of the present study was to determine the effect of preconditioning with gentamicin on LLC-PK1 cells. Preconditioning was induced in LLC-PK1 cells by 24-h exposure to 2.0 mM gentamicin (G/IU). After 4 or 15 days of preconditioning, cells were again exposed to gentamicin (2.0 mM) and compared to untreated control or G/IU cells. Necrosis and apoptosis were assessed by acridine orange and HOESCHT 33346. Nitric oxide (NO) and endothelin-1 were assessed by the Griess method and available kit. Heat shock proteins were analyzed by Western blotting. After 15 days of preconditioning, LLC-PK1 cells exhibited a significant decrease in necrosis (23.5 ± 4.3 to 6.5 ± 0.3%) and apoptosis (23.5 ± 4.3 to 6.5 ± 2.1%) and an increase in cell proliferation compared to G/IU. NO (0.177 ± 0.05 to 0.368 ± 0.073 ìg/mg protein) and endothelin-1 (1.88 ± 0.47 to 2.75 ± 0.53 pg/mL) production significantly increased after 15 days of preconditioning compared toG/IU. No difference in inducible HSP 70, constitutive HSC 70 or HSP 90 synthesis in tubular cells was observed afterpreconditioning with gentamicin. The present data suggest that preconditioning with gentamicin has protective effects on proximal tubular cells, that involved NO synthesis but not reduction of endothelin-1 or production of HSP 70, HSC 70, or HSP 90. We conclude that preconditioning could be a useful tool to prevent the nephrotoxicity induced by gentamicin.

Transforming growth factor-beta Does Not Induce Endothelin-1 Secretion in Primary Cultured Human Tenon's Fibroblasts

No abstract available.

Acciones de endotelina 1 y angiotensina II en embarazos complicados con preeclampsia / Endothelin 1 and angiotensin II in preeeclampsia

Introduction. It is generally thought that development of hypertension in preeclampsia (PE) is due to generalized endothelial dysfunction and/or results from an imbalance in the production and/or action of vasoactive factors, resulting in higher citosolic Ca2+ concentration which in turn leads to vasoconstriction and decreased blood pressure perfusion in organs, including the fetoplacental unit. Among vasoactive factors involved in blood pressure regulation, endothelin 1 (ET-1) and angiotensin II (Ang II) regulate citosolic Ca2+ concentrations and therefore are considered in this review. PE is associated with higher circulating and placental ET-1 levels, observation that explains, at least in part, vasoconstriction and oxidative stress. Higher and lower Ang II sensitivity seen in PE and normal pregnancy, respectively, could not be explained by changes in renin-angiotensin system components, including Ang II receptors (ATI). During normal pregnancy, ATI receptors are found as monomers and are inactivated by reactive oxygen species (ROS) leading to lower Ang II sensitivity. In contrast, PE is associated with increased ATl/bradicinin receptors (B2) heterodimers which are resistant to inactivation by ROS, maintaining increased ATI-receptor stimulated signaling in PE. In adittion, AT-1 agonistic antibodies (AT1-AA) obtained from PE women increases intracellular Ca2+, NADPH oxidase components and ROS, effects not observed with normal pregnancy AT1-AA. Conclusion. High ET-1 levels, the presence of AT1/B2 receptor heterodimers and increased AT1-AA are involved, at least in part, in the hypertensive and oxidative stress states in PE.

Introducción. Se reconoce que el desarrollo de la hipertensión en la preeclampsia (PE) resulta del daño endotelial generalizado y/o de la falta de equilibrio en la producción y/o acción de agentes vasoactivos, lo que conlleva al incremento en la concentración citosólica de Ca2+ que resulta en vasoconstricción y disminución de la perfusión sanguínea en los órganos, incluyendo la unidad fetoplacentaria. Dentro de los factores vaso-activos que regulan la presión arterial, en la presente revisión se consideró a la endotelina 1 (ET-1) y a la angiotensina II (Ang II), factores que regulan la concentración citosólica de Ca2+. En comparación con el embarazo normal, la PE se asocia con mayor concentración en suero y placenta de ET-1, lo que explica en parte la vasoconstricción y el estado de estrés oxidativo. La respuesta exagerada en la PE y el estado de refractariedad en el embarazo normal a la Ang II no pueden explicarse por componentes del sistema renina-angiotensina, incluyendo a los receptores de Ang II (ATI). Durante el embarazo normal los receptores AT-1 se encuentran en forma de monómeros y son inactivados por las especies reactivas de oxígeno (ROS), lo que se asocia con menor respuesta a Ang II. En cambio, la respuesta exagerada a la Ang II durante la PE puede deberse a la heterodimerizacion de los receptores ATI con los de bradicinina (B2), estado que les confiere resistencia a la inactivación por las especies reactivas de oxígeno (ROS), lo que explica el incremento en la concentración del Ca2+ intracelular. Además, los anticuerpos agonistas del receptor ATI (AT1-AA) de mujeres PE aumenta la concentración de Ca2+ intracelular, de la NADPH oxidasa y de ROS, efectos que no se presentan al utilizar AT1-AA de embarazadas normotensas. Conclusión. Las altas concentraciones de ET-1, la presencia de receptores ATI en forma de heterodimeros ATI/ B2 y el aumento en los AT1-AA explican en parte, el estado de hipertensión y de estrés oxidativo de la PE.

Estrogen and Enalapril attenuate the Development of Right Ventricular Hypertrophy induced by Monocrotaline in Ovariectomized Rats

The present study evaluated the importance of ovarian functions and the renin-angiotensin system in the progression of the right ventricular (RV) hypertrophy. Female Sprague-Dawley rats were bilaterally ovariectomized (Ovx) and injected with monocrotaline (MCT, 60 mg/kg, sc). Four weeks after MCT-treatment, only the male and Ovx female rats showed marked RV hypertrophy. The hypertrophied RV of the male-MCT and Ovx-MCT rats exhibited remarkably elevated renin mRNA levels. Gene expression levels of angiotensinogen, TGF-beta1, and endothelin-1 in the hypertrophied RV also increased, but to the less degree than did the renin mRNA. To investigate beneficial effects of estrogen or enalapril on progression of the pulmonary hypertension and RV hypertrophy, histological changes of the lung and heart were examined. Sham-MCT female rats showed histological changes indicating pulmonary hypertension without RV hypertrophy. In contrast, Ovx-MCT rats showed marked RV hypertrophy with pathological changes, denoting severe pulmonary and myocardial injuries. Estrogen-or enalapril-treated Ovx-MCT rats did not show RV hypertrophy, and showed remarkably ameliorated ultrastructural changes in the lung and RV. These results from this rat model suggest that both estrogen and inhibition of the renin-angiotensin system have protective functions against the development of the pulmonary hypertension and cardiac remodeling.

Endothelin-1 and nitric oxide in normal pregnancy and pre-eclampsia

Nitric oxide [NO] is a vasorelaxant agent, while endothelin-1 [Et-1] is a potent vasoconstrictor peptide. In this study, maternal venous plasma nitrite [N02] + nitrate [N03], stable metabolites of NO and ET-1 were measured in 20 non-pregnant cases, 20 normal pregnancy and 20 preeclamptic pregnancy. There was a significant increase in N02 + N03 and a significant decrease in ET-1 in normal pregnancy. In preeclampsia, N02 + N03 was significantly lower, while ET-1 was significantly higher than in normal pregnancy. There was a significant negative correlation between N02 + N03 and ET-1 in preeclamptic cases. Neither NO nor ET-1 correlated with mean arterial pressure. These data indicated that preeclampsia may reflect a state of impaired NO syntheses and increased ET-1 production. The pathophysiologic mechanism is a failure of vasodilatation and decreased vascular reactivity characteristic of normal pregnancy together with enhancement of vasoconstriction. Although the changes in NO and ET-1 are related to hypertension in preeclampsia, other mechanisms are probably activated