RESUMO
The potential inhibitory effect of the insulin mimicking agent, vanadium on type 2 diabetes mellitus (T2DM)induced alterations to the aorta ultrastructure associated with the suppression of dyslipedima and biomarkers of inflammation has not been investigated before. Therefore, we tested whether vanadium can protect against aortic injury induced secondary to T2DM possibly via the inhibition of blood lipid and inflammatory biomarkers. T2DM was induced in rats by a high-fat diet and streptozotocin (50 mg/ kg), and the treatment group started vanadium treatment five days post diabetic induction and continued until being sacrificed at week 10. Using light and electron microscopy examinations, we observed in the model group substantial damage to the aorta tissue such as damaged endothelium, degenerative cellular changes with vacuolated cytoplasm and thickened internal elastic lamina that were substantially ameliorated by vanadium. Administration of vanadium to diabetic rats also significantly (p<0.05) reduced blood levels of glucose, hyperlipidemia and biomarkers of inflammation (TNF-a, IL-6). We conclude that vanadium protects against T2DM-induced aortic ultrastructural damage in rats, which is associated with the inhibition of blood sugar and lipid and inflammatory biomarkers.
El potencial efecto inhibidor del agente imitador de la insulina, el vanadio en las alteraciones inducidas por la diabetes mellitus tipo 2 (DM2) en la ultraestructura de la aorta, asociada con la supresión de dislipidemia y los biomarcadores de inflamación no se ha investigado anteriormente. El objetivo fue estudiar las propiedades del vanadio para proteger contra la lesión aórtica inducida a la DM2, a través de la inhibición de los lípidos sanguíneos y los biomarcadores inflamatorios. La DM2 fue inducida en ratas con una dieta alta en grasas y estreptozotocina (50 mg / kg), y el grupo de tratamiento fue sometido a un régimen continuo con vanadio, cinco días después de la inducción diabética hasta ser sacrificadas en la semana 10. Se utilizaron exámenes de luz y microscopía electrónica en el grupo modelo y se observó un daño sustancial al tejido de la aorta, como también en el endotelio; los cambios celulares degenerativos con citoplasma vacuolado y lámina elástica interna engrosada mejoró sustancialmente con vanadio. La administración de vanadio a ratas diabéticas también redujo significativamente (p <0,05) los niveles sanguíneos de la glucosa, hiperlipidemia y los biomarcadores de inflamación (TNFa, IL-6). En conclusión, el vanadio protege contra el daño ultraestructural aórtico inducido por T2DM en ratas, que es asociado con la inhibición del azúcar en la sangre y los biomarcadores de lípidos y de inflamatorios.
Assuntos
Animais , Masculino , Ratos , Aorta/efeitos dos fármacos , Vanádio/administração & dosagem , Diabetes Mellitus Tipo 2/complicações , Aorta/lesões , Aorta/ultraestrutura , Doenças da Aorta/etiologia , Vanádio/farmacologia , Ratos Sprague-Dawley , Microscopia Eletrônica de Transmissão , Modelos Animais de Doenças , Dislipidemias/tratamento farmacológico , Inflamação/tratamento farmacológicoRESUMO
Arterial hypertension is a condition associated with endothelial dysfunction, accompanied by an imbalance in the production of reactive oxygen species (ROS) and NO. The aim of this study was to investigate and elucidate the possible mechanisms of sildenafil, a selective phosphodiesterase-5 inhibitor, actions on endothelial function in aortas from spontaneously hypertensive rats (SHR). SHR treated with sildenafil (40â¯mg/kg/day, p.o., 3â¯weeks) were compared to untreated SHR and Wistar-Kyoto (WKY) rats. Systolic blood pressure (SBP) was measured by tail-cuff plethysmography and vascular reactivity was determined in isolated rat aortic rings. Circulating endothelial progenitor cells and systemic ROS were measured by flow cytometry. Plasmatic total antioxidant capacity, NO production and aorta lipid peroxidation were determined by spectrophotometry. Scanning electron microscopy was used for structural analysis of the endothelial surface. Sildenafil reduced high SBP and partially restored the vasodilator response to acetylcholine and sodium nitroprusside in SHR aortic rings. Using selective inhibitors, our experiments revealed an augmented participation of NO, with a simultaneous decrease of oxidative stress and of cyclooxygenase-1 (COX-1)-derived prostanoids contribution in the endothelium-dependent vasodilation in sildenafil-treated SHR compared to non-treated SHR. Also, the relaxant responses to sildenafil and 8-Br-cGMP were normalized in sildenafil-treated SHR and sildenafil restored the pro-oxidant/antioxidant balance and the endothelial architecture. In conclusion, sildenafil reverses endothelial dysfunction in SHR by improving vascular relaxation to acetylcholine with increased NO bioavailability, reducing the oxidative stress and COX-1 prostanoids, and improving cGMP/PKG signaling. Also, sildenafil reduces structural endothelial damage. Thus, sildenafil is a promising novel pharmacologic strategy to treat endothelial dysfunction in hypertensive states reinforcing its potential role as adjuvant in the pharmacotherapy of cardiovascular diseases.
Assuntos
Anti-Hipertensivos/farmacologia , Aorta/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Ciclo-Oxigenase 1/metabolismo , Endotélio Vascular/efeitos dos fármacos , Hipertensão/tratamento farmacológico , Proteínas de Membrana/metabolismo , NADP/metabolismo , Óxido Nítrico/metabolismo , Citrato de Sildenafila/farmacologia , Vasodilatadores/farmacologia , Animais , Aorta/enzimologia , Aorta/fisiopatologia , Aorta/ultraestrutura , GMP Cíclico/metabolismo , Modelos Animais de Doenças , Células Progenitoras Endoteliais/efeitos dos fármacos , Células Progenitoras Endoteliais/metabolismo , Células Progenitoras Endoteliais/ultraestrutura , Endotélio Vascular/enzimologia , Endotélio Vascular/fisiopatologia , Endotélio Vascular/ultraestrutura , Hipertensão/enzimologia , Hipertensão/patologia , Hipertensão/fisiopatologia , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Estresse Oxidativo/efeitos dos fármacos , Inibidores da Fosfodiesterase 5/farmacologia , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Transdução de Sinais , Vasodilatação/efeitos dos fármacosRESUMO
Excessive consumption of carbohydrate and fat increases the risk of cardiovascular disease. We sought to determine the potential ultrastructural alterations in large blood vessels induced by a high fat and fructose diet (HFD) in a rat model of prediabetes. Rats were either fed with HFD (model group) or a standard laboratory chow (control group) for 15 weeks before being sacrificed. The harvested thoracic aorta tissues were examined using transmission electron microscopy (TEM), and blood samples were assayed for biomarkers of pre-diabetes.TEM images showed that HFD induced profound pathological changes to the aortic wall layers, tunica intima and tunica media ultrastructures in the pre-diabetic rats as shown by apoptotic endothelial cells with pyknotic nuclei, damaged basal lamina, deteriorated smooth muscle cells that have irregular plasma membranes, shrunken nucleus with clumped nuclear chromatin, damaged mitochondria and few cytoplasmic lipid droplets and vacuoles. In addition, HFD significantly (p<0.05) decreased adiponectin and increased biomarkers of lipidemia, glycaemia, inflammation, oxidative stress, vascular injury such as soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion protein 1 (sVCAM-1), endothelin-1 (ET-1), and coagulation and thrombosis such as Von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1), compared to normal levels of these parameters in the control group. Thus, we demonstrated that feeding rats with a HFDisable to develop a pre-diabetic animal model that is useful to study the aortic ultrastructural alterations.
El consumo excesivo de carbohidratos y grasas aumenta el riesgo de enfermedades cardiovasculares. Intentamos determinar las posibles alteraciones ultraestructurales en los grandes vasos sanguíneos, inducidas por una dieta alta en grasas y fructosa (HFD) en un modelo de rata de prediabetes. Las ratas se alimentaron con HFD (grupo modelo) o una comida de laboratorio estándar (grupo de control) durante 15 semanas antes de ser sacrificadas. Los tejidos de la aorta torácica recolectados se examinaron mediante microscopía electrónica de transmisión (TEM) y las muestras de sangre se analizaron para detectar biomarcadores de prediabetes. Las imágenes TEM mostraron que HFD indujo cambios patológicos profundos en las capas de la pared aórtica, túnica íntima y túnica media en la ratas pre-diabéticas como lo muestran las células endoteliales apoptóticas con núcleos picnóticos, lámina basal dañada, células musculares lisas deterioradas que tienen membranas plasmáticas irregulares, núcleo encogido con cromatina nuclear aglomerada, mitocondrias dañadas y pocas gotitas lipídicas citoplásmicas y vacuolas. Además, HFD presentó disminución significativa de adiponectina (p <0,05), y aumento de biomarcadores de lipidemia, glucemia, inflamación, estrés oxidativo, lesión vascular como la molécula de adhesión intercelular soluble 1 (sICAM-1), proteína de adhesión de células vasculares soluble 1 (sVCAM-1), endotelina 1 (ET-1), y la coagulación y la trombosis, como el factor de Von Willebrand (vWF), y el inhibidor del activador del plasminógeno-1 (PAI -1), en comparación con los niveles normales de estos parámetros en el grupo de control. Por tanto, la alimentación de ratas con HFD es capaz de desarrollar un modelo animal prediabético que es útil para estudiar las alteraciones ultraestructurales aórticas.
Assuntos
Animais , Aorta Torácica/patologia , Aorta Torácica/ultraestrutura , Estado Pré-Diabético/patologia , Aorta/patologia , Aorta/ultraestrutura , Estado Pré-Diabético/metabolismo , Gorduras na Dieta/efeitos adversos , Ratos Sprague-Dawley , Microscopia Eletrônica de Transmissão , Modelos Animais de Doenças , Lesões do Sistema Vascular/etiologia , Lesões do Sistema Vascular/patologia , FrutoseRESUMO
Stem cells are characterized by their ability to differentiate into multiple cell lineages and display the paracrine effect. The aim of this work was to evaluate the effect of therapy with bone marrow-derived cells (BMCs) on glucose, lipid metabolism, and aortic wall remodeling in mice through the administration of a high-fat diet and subsequent BMCs transplantation. C57BL/6 mice were fed a control diet (CO group) or an atherogenic diet (AT group). After 16 weeks, the AT group was divided into 4 subgroups: an AT 14 days group and AT 21 days group that were given an injection of vehicle and sacrificed after 14 and 21 days, respectively, and an AT-BMC 14 days group and AT-BMC 21 days group that were given an injection of BMCs and sacrificed after 14 and 21 days, respectively. The BMCs transplant had reduced blood glucose, triglycerides, and total cholesterol. There was no significant difference in relation to body mass between the transplanted groups and non-transplanted groups, and all were different than CO. There was no significant difference in the glycemic curve among AT 14 days, AT-BMC 14 days, and AT 21 days, and these were different than the CO and the AT-BMC 21 days groups. The increased thickness of the aortic wall was observed in all atherogenic groups, but was significantly smaller in group AT-BMC 21 days compared to AT 14 days and AT 21 days. Vacuoles in the media tunic, delamination and the thinning of the elastic lamellae were observed in AT 14 days and AT 21 days. The smallest number of these was displayed on the AT-BMC 14 days and AT-BMC 21 days. Marking to CD105, CD133, and CD68 were observed in AT 14 days and AT 21 days. These markings were not observed in AT-BMC 14 days or in AT-BMC 21 days. Electron micrographs show the beneficial remodeling in AT-BMC 14 days and AT-BMC 21 days, and the structural organization was similar to the CO group. Vesicles of pinocytosis, projection of smooth muscle cells, and delamination of the internal elastic lamina are seen in groups AT 14 days and AT 21 days. Endothelial cells were preserved, and regular and continuous contour in internal elastic lamelae were observed in the CO, the AT-BMC 14 days, and AT-BMC 21 days groups. In conclusion, in an atherosclerotic model using mice and atherogenic diet, the injection of BMCs improves glucose, lipid metabolism, and causes a beneficial remodeling of the aortic wall.
Assuntos
Aorta/patologia , Aterosclerose/terapia , Transplante de Medula Óssea , Animais , Aorta/ultraestrutura , Glicemia/análise , Peso Corporal , Colesterol/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Transmissão , Triglicerídeos/sangueRESUMO
In ascending aorta aneurysms (AscAA) the whole vessel wall dilates, while in aortic dissections (AD) the wall cleaves into two sheets. Both may present fine elastic fragmentation and a decrease in collagen. We analyzed whether alterations in the three-dimensional structure of these fibers could be involved in the pathogenesis of AscAA/AD. Specimens obtained at surgery for these diseases (n = 4 for each) and on coronary artery bypass surgery (controls, n = 4) were submitted to treatments which either preserve collagen or the elastic structure. These samples were examined by scanning electron microscopy. In all groups most of the collagen fibers were packed, forming laminar structures very similar to the elastic lamellae. In AscAA/AD, the fibers showed signs of degradation and/or fragmentation. Elastic tissue was distributed in large sheets with fenestrations, with smaller branches between them. In 1 of the dissection cases and 2 of the aneurysm cases elastic sheet fragmentation, which under light microscopy seems to be located at random, had a pattern of clefts which were irregular but approximately transversal to the main axis of the wall. The recognition of this pattern and the degradation/fragmentation of collagen and elastic fibrils facilitates understanding of why the wall is weak and affected by aneurysms and dissections.
Assuntos
Aorta/ultraestrutura , Aneurisma Aórtico/patologia , Dissecção Aórtica/patologia , Microscopia Eletrônica de Varredura , Idoso , Estudos de Casos e Controles , Dilatação Patológica , Progressão da Doença , Tecido Elástico/ultraestrutura , Colágenos Fibrilares/ultraestrutura , Humanos , Pessoa de Meia-Idade , PrognósticoRESUMO
BACKGROUND: Atherosclerotic cardiovascular disease is a chronic inflammatory condition. Thiazolidinediones (TZDs) are used to enhance sensitivity to insulin and have demonstrated a protective effect over a variety of cardiovascular markers and risk factors. Controversially, the TZDs are associated with the development of heart failure. Thus, lines of research have invested in the search for new molecules in order to obtain more selective and less harmful treatment alternatives for the pathogenesis of atherosclerosis and its risk factors. METHODS: Animals were fed a diet rich in fat for 10 weeks. In the last 2 weeks, animals received either pioglitazone, LPSF/GQ-02, or LPSF/GQ-16 daily through gavage. At the end of the treatment, blood was collected for biochemical analysis and the aortas were dissected for subsequent analyses. RESULTS: No changes in the blood lipid profile were found following the use of the drugs in comparison to the control. However, the new thiazolidine derivatives were more efficient in improving insulin resistance in comparison to pioglitazone and the control group. Morphometric analyses revealed that neither pioglitazone nor LPSF/GQ16 led to satisfactory effects over atherosclerosis. However, LPSF/GQ-02 led to a reduction in area of the atherosclerotic lesions. Ultrastructural analyses revealed extensive degeneration of the endothelium and an increase in apoptotic cells in the subendothelial space following the use of pioglitazone and LPSF/GQ-16. However, LPSF/GQ-02 caused minimal cell alterations in the aortic endothelium. Regarding markers, endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase 9 (MMP-9), LPSF/GQ-16, and pioglitazone exerted similar effects, increasing the expression of MMP-9, and had no effect on the expression of eNOS compared with the control group. On the other hand, LPSF/GQ-02 was effective in reducing the expression of MMP-9 and increased eNOS significantly. CONCLUSIONS: The results suggest that the new thiazolidine derivative LPSF/GQ-02 is a promising candidate for the treatment of atherosclerosis.
Assuntos
Aorta/efeitos dos fármacos , Doenças da Aorta/tratamento farmacológico , Aterosclerose/tratamento farmacológico , Fármacos Cardiovasculares/farmacologia , Receptores de LDL/deficiência , Tiazolidinedionas/farmacologia , Tiazolidinas/farmacologia , Animais , Aorta/metabolismo , Aorta/ultraestrutura , Doenças da Aorta/genética , Doenças da Aorta/patologia , Apoptose/efeitos dos fármacos , Aterosclerose/sangue , Aterosclerose/genética , Aterosclerose/patologia , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Western Blotting , Fármacos Cardiovasculares/toxicidade , Modelos Animais de Doenças , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Imuno-Histoquímica , Insulina/sangue , Resistência à Insulina , Lipídeos/sangue , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Óxido Nítrico Sintase Tipo III/metabolismo , Pioglitazona , Placa Aterosclerótica , Receptores de LDL/genética , Tiazolidinedionas/toxicidade , Tiazolidinas/toxicidade , Fatores de TempoRESUMO
OBJECTIVE: Morphological study that searched to authenticate the presence of sinoaortic baroreceptor inputs within the dorsolateral medullary nucleus under electron microscopy analysis. METHODS: After a 5-day survival period, 9 baroreceptor-denervated rats deeply anaesthetized with equithesin were transcardially perfused and their brains were histologically processed. RESULTS: The neuronal cytoarchitecture of the paratrigeminal nucleus comprehends afferent projections from other nuclei that have a distributive character regarding visceral and nociceptive functions in the cardiovascular reflex integration response. CONCLUSION: The medial portion of the nucleus receives afferent projections of the rostral ventrolateral medulla, as shown by retrograde neurotracing studies. The present results show that the medial extent of the paratrigeminal nucleus contains degenerated axoplasmic cellular components in sinoaortic deafferented rats. The number of degenerated axonal fibers was also larger in this area of the nucleus.
Assuntos
Sistema Nervoso Autônomo/ultraestrutura , Axônios/fisiologia , Degeneração Neural/patologia , Neurônios Aferentes/ultraestrutura , Pressorreceptores/ultraestrutura , Núcleo Espinal do Trigêmeo/ultraestrutura , Animais , Aorta/inervação , Aorta/ultraestrutura , Sistema Nervoso Autônomo/fisiologia , Axônios/ultraestrutura , Masculino , Microscopia Eletrônica de Varredura , Degeneração Neural/fisiopatologia , Neurônios Aferentes/fisiologia , Pressorreceptores/fisiologia , Ratos , Ratos Wistar , Núcleo Espinal do Trigêmeo/fisiologiaRESUMO
BACKGROUND: Vitamin A deficiency induces activation of NF-kB and impairs activities of antioxidant enzymes in aorta. AIM OF THE STUDY: We study the effect of vitamin A deficiency on the aorta histoarchitecture and the possibly contribution of its prooxidant and inflammatory effects to artery alterations. METHODS: Twenty-one-day-old Wistar male rats were fed during 3 months with vitamin A-deficient diet (-A, n = 8) or the same diet containing 8 mg of retinol palmitate/kg of diet (+A, control, n = 8). In aortas, thiobarbituric reactive substances and reduced glutathione levels were measured by spectrophotometry. Expressions of TNF-alpha, NOX-2, VCAM-1, and TGF-beta1 were assessed by RT-PCR and Western Blot. The morphology of aorta was examined by light and transmission electron microscopy. RESULTS: In -A rats, high levels of TBARS in serum and aorta and low levels of GSH in aorta were found. An increased expression of TNF-alpha, NOX-2, VCAM-1, and TGF-beta1 in aorta from -A rats was observed. Examination of the intimal layer by light microscopy indicated the presence of an irregular surface in -A aortas. TEM studies showed large vacuoles and multivesicular bodies along the endothelium and also multivesicular bodies in the subendothelial space of aortas from -A rats. Furthermore, the histological appearance of internal elastic lamina was different from control. Small vesicles in the medial layer were observed in aortas from vitamin A-deficient rats. CONCLUSIONS: Vitamin A deficiency produces histoarchitectural alterations in aorta, which can be associated, at least in part, to the oxidative stress and inflammation induced by vitamin A deficiency.
Assuntos
Aorta/imunologia , Aorta/ultraestrutura , Estresse Oxidativo , Vasculite/etiologia , Deficiência de Vitamina A/patologia , Deficiência de Vitamina A/fisiopatologia , Animais , Aorta/metabolismo , Citocinas/genética , Citocinas/metabolismo , Regulação da Expressão Gênica , Glutationa/metabolismo , Masculino , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Corpos Multivesiculares/ultraestrutura , NADPH Oxidase 2 , NADPH Oxidases/genética , NADPH Oxidases/metabolismo , Oxirredução , RNA Mensageiro/metabolismo , Distribuição Aleatória , Ratos , Ratos Wistar , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Túnica Íntima/ultraestrutura , Vacúolos/ultraestrutura , Molécula 1 de Adesão de Célula Vascular/genética , Molécula 1 de Adesão de Célula Vascular/metabolismo , Deficiência de Vitamina A/imunologia , Deficiência de Vitamina A/metabolismoRESUMO
This work aimed to analyze the effect of low-intensity exercise training on ultrastructural and molecular aortic remodeling. Male Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were allocated into four groups: sedentary WKY (SED-WKY), exercised WKY (EX-WKY, 1 h/day, 5 days/week treadmill exercise training), sedentary SHR (SED-SHR), and exercised SHR (EX-SHR). EX-SHR showed blood pressure reduction of 26% in comparison to SED-SHR after 1 month of exercise (P<0.05). At the 20th week, BP level was not different between EX-SHRs and WKYs. Circumferential wall tension (CWT) was higher by 77% in SED-SHRs than in SED-WKYs (P<0.001). Exercise training reduced CWT by 30% in EX- vs. SED-SHR (P<0.001). In SED-SHRs, endothelial cells showed large and numerous cytoplasmatic vacuoles, fragmented inner elastic lamina and scarce elastin and fibrillin, while exercise training ameliorated it in EX-SHR group. The highest eNOS immunodensity was observed in EX-SHR, which was 50% higher than EX-WKY (P<0.01) and 120% higher than SED-SHR (P<0.0001). In conclusion, present findings indicate beneficial effects of exercise training in hypertensive rats since it increased elastin, fibrillin and eNOS content in the aortic wall.
Assuntos
Aorta/metabolismo , Elastina/metabolismo , Hipertensão/metabolismo , Proteínas dos Microfilamentos/metabolismo , Óxido Nítrico/metabolismo , Condicionamento Físico Animal/fisiologia , Animais , Aorta/química , Aorta/ultraestrutura , Pressão Sanguínea/fisiologia , Elastina/ultraestrutura , Fibrilinas , Hipertensão/reabilitação , Immunoblotting , Imuno-Histoquímica , Masculino , Proteínas dos Microfilamentos/ultraestrutura , Microscopia Eletrônica de Transmissão , Óxido Nítrico Sintase Tipo III/metabolismo , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Resistência à TraçãoRESUMO
The arrangement and interconnections between various components of the aortic wall influence its physicomechanical properties and functional alterations that occur in disease and ageing. The goat is a suitable model for studying cardiovascular disease, but details of the intrinsic organization of its aorta are unknown. This study therefore investigated the histomorphology of aortic tunica media in the goat by transmission electron microscopy. Sixteen healthy juvenile and adult domestic male goats (capra hircus) purchased from livestock farms in the outskirts of Nairobi were used in the study. The animals were euthanized with overdose of sodium pentabarbitone 20mg/kg, and fixed with 3 percent phosphate buffered glutaraldehyde solution by gravimetric perfusion. Specimens obtained from the thoracic aorta (T9) were post fixed in osmium tetroxide, and prepared for durcupan embedding. Ultrathin sections stained with uranyl acetate/lead citrate were examined by EM 201 Phillips © electron microscope. Elastic and collagen fibres were structurally interconnected. Elastic lamellae, collagen and elastic fibres were linked to smooth muscle cells through areas of high electron density while smooth muscle cells were interconnected various inter cellular connections. The physical interlinkages between the components of the tunica media confer plasticity, adaptability and flexibility to the aortic wall enabling it to function as a mechanically homogenous structure. Disruptions of this structure in atherosclerosis and aging may disturb the vascular integrity and predispose to aneurysm formation.
Las relaciones e interconexiones entre los distintos componentes de la pared aórtica influyen en sus propiedades fisicomecánicas y en las alteraciones funcionales que se producen en la enfermedad y el envejecimiento. La cabra es un modelo adecuado para el estudio de las enfermedades cardiovasculares, pero los detalles de la organización propia de la aorta son desconocidos. Por tanto, se investigó la histomorfología de la túnica media aórtica en la cabra mediante microscopía electrónica de transmisión. Fueron utilizadas 16 cabras (Capra hircus) domésticas macho, jóvenes y adultas sanas, adquiridas en las explotaciones ganaderas en las afueras de Nairobi fueron utilizadas. Los animales fueron sacrificados con una sobredosis de 20 mg/kg de pentobarbital sódico, y se fijaron con una solución de fosfato de glutaraldehído al 3 por ciento por perfusión gravimétrica. Las muestras obtenidas de la aorta torácica (T9) fueron puestas en tetróxido de osmio, y se prepararon para inclusión en durcupan. Secciones ultrafinas teñidas con acetato de uranilo y citrato de plomo fueron examinados por microscopio electrónico EM 201 Phillips©. Fibras elásticas y colágenas estaban interconectadas estructuralmente. Láminas elásticas, de colágeno y fibras elásticas estaban conectadas a células de músculo liso a través de áreas de alta densidad de electrones, mientras que, las células musculares lisas estaban interconectados entre diferentes conexiones celulares. Las interconexiones físicas entre los componentes de la túnica media confieren plasticidad, adaptabilidad y flexibilidad a la pared aórtica, lo que le permite funcionar como una estructura mecánica homogénea. Las interrupciones de estas estructuras en la aterosclerosis y el envejecimiento pueden alterar la integridad vascular y predisponer a la formación de aneurismas.