A Single Resistance Exercise Session Improves Aortic Endothelial Function in Hypertensive Rats / Uma Única Sessão de Exercício Resistido Melhora a Função Endotelial Aórtica em Ratos Hipertensos

Abstract Background: Physical exercise is an important tool for the improvement of endothelial function. Objective: To assess the effects of acute dynamic resistance exercise on the endothelial function of spontaneously hypertensive rats (SHR). Methods: Ten minutes after exercise, the aorta was removed to evaluate the expression of endothelial nitric oxide synthase (eNOS), phosphorylated endothelial nitric oxide synthase (p-eNOS1177) and inducible nitric oxide synthase (iNOS) and to generate concentration-response curves to acetylcholine (ACh) and to phenylephrine (PHE). The PHE protocol was also performed with damaged endothelium and before and after NG-nitro-L-arginine methyl ester (L-NAME) and indomethacin administration. The maximal response (Emax) and the sensitivity (EC50) to these drugs were evaluated. Results: ACh-induced relaxation increased in the aortic rings of exercised (Ex) rats (Emax= -80 ± 4.6%, p < 0.05) when compared to those of controls (Ct) (Emax = -50 ± 6.8%). The Emax to PHE was decreased following exercise conditions (95 ± 7.9%, p < 0.05) when compared to control conditions (120 ± 4.2%). This response was abolished after L-NAME administration or endothelial damage. In the presence of indomethacin, the aortic rings' reactivity to PHE was decreased in both groups (EC50= Ex -5.9 ± 0.14 vs. Ct -6.6 ± 0.33 log µM, p < 0.05 / Emax = Ex 9.5 ± 2.9 vs. Ct 17 ± 6.2%, p < 0.05). Exercise did not alter the expression of eNOS and iNOS, but increased the level of p-eNOS. Conclusion: A single resistance exercise session improves endothelial function in hypertensive rats. This response seems to be mediated by increased NO production through eNOS activation.

Resumo Fundamento: O exercício físico é uma importante ferramenta para o aprimoramento da função endotelial. Objetivo: Avaliar os efeitos do exercício dinâmico resistido agudo na função endotelial de ratos espontaneamente hipertensos (SHR). Métodos: Após 10 minutos de exercício, a aorta foi removida para avaliação da expressão de óxido nítrico sintase endotelial (eNOS), óxido nítrico sintase endotelial fosforilada (p-eNOS1177) e óxido nítrico sintase endotelial induzível (iNOS), e para a construção de curvas concentração-resposta de acetilcolina (ACT) e fenilefrina (FEN). O protocolo FEN foi também realizado com lesão endotelial e antes e depois da administração de N-nitro-L-arginina metil éster (L-NAME) e indometacina. A resposta máxima (Emax) e a sensibilidade (EC50) a esses fármacos foram avaliadas. Resultados: Houve aumento do relaxamento induzido por ACT nos anéis aórticos dos ratos exercitados (Ex) (Emax = -80 ± 4,6%; p < 0,05) quando comparado àquele dos controles (Ct) (Emax = -50 ± 6,8%). A Emax à FEN diminuiu após exercício (95 ± 7,9%; p < 0,05) quando comparada àquela dos controles (120 ± 4,2%). Tal resposta foi abolida após administração de L-NAME ou lesão endotelial. Na presença de indometacina, a reatividade dos anéis aórticos à FEN diminuiu nos dois grupos (EC50= Ex -5,9 ± 0,14 vs. Ct -6,6 ± 0,33 log µM; p < 0,05/ Emax = Ex 9,5 ± 2,9 vs. Ct 17 ± 6,2%; p < 0,05). O exercício não alterou a expressão de eNOS e de iNOS, mas aumentou o nível de p-eNOS. Conclusão: Uma única sessão de exercício resistido melhora a função endotelial em ratos hipertensos. Essa resposta parece ser mediada por elevação da produção de NO através de ativação de eNOS.

Presentation of an experimental method to induce in vitro ("organ chambers") respiratory acidosis and its effect on vascular reactivity

PURPOSE: To create in vitro a model to generate acidosis by CO2 bubbling "organ chambers", which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity. METHODS: Eighteen male Wistar rats (230-280g) were housed, before the experiments, under standard laboratory conditions (12h light/dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO2) and pure CO2. RESULTS: 1) 100% CO2, pH variation very fast, pH minimum 6.0; 2) 90%CO2 pH variation bit slower, pH minimum6.31; 3) 70%CO2, pH variation slower, pH minimum 6.32; 4) 50% CO2, pH variation slower, pH minimum 6:42; 5) 40 %CO2, Adequate record, pH minimum 6.61, and; 6) 30 %CO2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO2 40%) was adopted, CONCLUSION: This gas mixture (O2 60% + CO2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force. .

Importancia médica del glucocáliz endotelial: Parte 2: su papel en enfermedades vasculares y complicaciones de la diabetes mellitus / Medical significance of endothelial glycocalyx: Part 2: Its role in vascular diseases and in diabetic complications

El glucocáliz endotelial es una capa constituida por glucosaminoglicanos, proteoglicanos y glucoproteínas que cubre al endotelio en su cara luminal. La participación del deterioro del glucocáliz endotelial parece esencial en los pasos iniciales de la fisiopatología de la aterosclerosis, de las complicaciones microangiopáticas de la diabetes mellitus y de la enfermedad venosa crónica. Los factores de riesgo de la aterosclerosis como la hipercolesterolemia, la hiperglucemia, la inflamación, el exceso de sodio y las fuerzas de tensión alteradas causan deterioro del glucocáliz. Esto provoca disfunción endotelial y permite la filtración de lipoproteínas (LDL) y de leucocitos al espacio subendotelial, iniciando la formación de la placa de ateroma. En la diabetes el glucocáliz adelgazado, principalmente por estrés oxidativo, posibilita la filtración de proteínas (albuminuria) y el trastorno endotelial de la microangiopatía. La hipertensión venosa crónica altera las fuerzas de tensión y daña el glucocáliz, lo que permite la filtración de leucocitos a las partes más profundas de la pared venosa, iniciando la inflamación y el deterioro morfológico y funcional de las venas que lleva a la enfermedad venosa crónica. El tratamiento con glucosaminoglicanos (sulodexida) logra prevenir o revertir el daño al glucocáliz endotelial y algunas de sus consecuencias; es eficaz en la enfermedad venosa crónica, especialmente con úlceras venosas. También ha sido útil en aterosclerosis obliterante de miembros inferiores y en la nefropatía diabética con albuminuria.

Endothelial glycocalyx is a layer composed by glycosaminoglycans, proteoglycans and glycoproteins attached to the vascular endothelial luminal surface. Shredding of glycocalyx appears as an essential initial step in the pathophysiology of atherosclerosis and microangiopathic complications of diabetes mellitus, as well as in chronic venous disease. Atherosclerosis risk factors, as hypercholesterolemia (LDL), hyperglycemia, inflammation, salt excess and altered shear stress can damage glycocalyx. This lead to endothelial dysfunction and allows LDL and leukocytes to filtrate to the subendothelial space initiating atheroma plaque formation. Degradation of glycocalyx in diabetes mellitus is mainly due to oxidative stress and enables protein filtration (albuminuria) and endothelial disorder of microangiopathy. Chronic venous hypertension brings to altered shears stress which results in shredded glycocalyx, this allows leukocytes to migrate into venous wall and initiate inflammation leading to morphologic and functional venous changes of the chronic venous disease. Treatment with glycosaminoglycans (sulodexide) prevents or recovers the damaged glycocalyx and several of its consequences. This drug improves chronic venous disease and promotes healing of chronic venous ulcers. It has also been useful in peripheral arterial obstructive disease and in diabetic nephropathy with albuminuria.

La dimetilarginina asimétrica, estructura e implicaciones patológicas / Asymmetric dimethylarginine, structure and pathological implications

La ateroesclerosis, es una enfermedad crónica, sistémica, inmuno-inflamatoria que afecta a la íntima arterial. La disfunción endotelial es la primera fase en la ateroesclerosis La disfunción endotelial está caracterizada por un daño y pérdida de la monocapa celular que cubre el interior de los vasos sanguíneos, denominada endotelio. Uno de los principales mediadores ara el mentenimieno de la integridad del endotelio, es el óxido nítrico (ON). La Dimetilarginina asimétrica (DMMA), es un inhibidor endógeno de la enzima sintasa del Óxido Nítrico (SON); se ha sugerido que DMAA sirve como un marcador de disfunción endotelial en enfermedades cardiovasculares. Asimismo, la DMAA representa un factor de riesgo para mortalidad cardiovascular, progresión de enfermedad crónica renal. Se ha encontrado valores elevados de DMAA en diferentes condiciones como hipercolesterolemia, aterosclerosis, hipertensión, insuficiencia renal crónica, insuficiencia crónica del corazón, diabetes y disfunsión eréctil.

Atherosclerosis is an immune inflammatory systemic, arterial disease. Endothelial dysfunction is the first stage in aterosclerosis. Atherosclerosis develops because of reactions occurring in vessel wall beginning with response to enothelial injury. Endothelial dysfunction is characterized with impairment and loss of monolayer cells covering the inside of the vessels, which is enothelium. One of the main mediators for the maintenance of the integrity of endothelium is Nitric Oxide (NO). The asymmtric Dimethilarginine (ADMA), is an endogenous inhibitor of the enzyme Nitric Oxide Synthase (NOS). ADMA has been suggested to serve as a biomarker of endothelial dysfunction in cardiovascular diseases. ADMA is a risk factor for endothelial dysfunction, cardiovascular mortality, and progression of chronic kidney disease. Elevated values of ADMA have been found in hypercholesterolemia, atherosclerosis, hypertension, chronic renal insufficiency, heart chronic failure, diabetes and erectile dysfunction.

Surface and total tissue factor activity of endothelial cells.

With a technic that was developed by us, we found that normal human umbilical vein endothelial cells (HUVEC) in culture characteristically had very little tissue factor (TF) activity either on the surface or in the cells which had been disrupted. In the presence of endotoxin (E. coli O26:B6), a trigger for thrombosis in septicemic patients, we could not detect an increased TF activity of HUVEC on its surface. However, an increase in TF (total TF) was detected after disruption of the cells. The increase in total TF was dose-dependent. Endotoxin at the concentration of 10 micrograms/ml caused around 5 fold increase in total TF activity compared to that of HUVEC in the absence of endotoxin.

Lack of interaction of angiotensin converting enzyme inhibitors with muscarinic and neuropeptide Y receptors

In studies conducted in patients undergoing cardiac catheterizations, some hemodynamic changes were observed after the acute sublingual administration of the angiotensin converting enzyme inhibitors (ACEI) captopril, enalapril, and lisinopril. These changes consisted of an increase in pulmonary artery pressure, pulmonary vascular resistance (PVR) and induction of hypoxia. The pressure changes were transitory and disappeared after 25 min. The possible mechanisms involved in these changes may relate to interactions of the ACEI with peripheral receptor systems for hormones and neurotransmitters. We have thus undertaken the task of evaluating the potential effect of ACEI on biological receptor molecules. We have begun with studies on muscarinic receptors, and the recently characterized neuropeptide Y (NPY) receptors of endothelial cells. Equilibrium binding assays with 3H-QNB have been conducted for muscarinic receptors using rat brain synaptosomes, due to its expression of multiple muscarinic receptors subtypes. In addition 125BH-NPY binding assays were conducted on intact adrenal medullary endothelial cells. Enalapril and captopril, 10(-7) to 10(-3) M, were not able to produce significant inhibition of either muscarinic or NPY receptor probes. The paradoxical changes elicited by sublingual ACEI seems not to involve interaction with muscarinic or NPY receptors

Barrera hematoencefálica y pasaje de drogas al sistema nervioso central: parte I: consideraciones generales, histológicas, bioquímicas y farmacológicas / Hematoencephalic barrier and passage of drugs into the central nervous system

El sitio anatómico de la barrera hematoencefálica es la capa de células del endotelio capilar cerebral con sus uniones estrechas ("tight junctions") intercelulares. Entonces, la capacidad de pasaje de las drogas hacia el compartimento cerebral está regida principalmente por su facilidad de atravesar la interfase lipídica de las membranas plasmáticas de dichas células, es decir su liposolubilidad. Los antibióticos, al no utilizar mecanismos especiales de transporte hematoencefálico, no escapan a esta regla. Algunos antibióticos, cuya utilización es necesaria en casos de infecciones del sistema nerviosos central -como los aminoglucósidos-, no presentan transporte adecuado a través de la barrera, y en esto se basa el desarrollo de técnicas para hacer llegar estas drogas al compartimiento cerebral, de las cuales la más difundida es la administración directa en el líquido cefalorraquídeo. De todos modos, sería interesante realizar estudios comparativos tendientes a definir la verdadera utilidad de drogas de reciente aparición, con espectro similar y mayor liposolubilidad -como las cefalosporinas modernas-, con el fin de evitar los inconvenientes derivados de la práctica de esas técnicas de soslayo de la barrera hematoencefálica