SHOX Duplication and Tall Stature in a Patient with Xq Deletion and Vascular Disease.

The anomalies of X chromosome are classified as numerical or structural. Concomitant structural anomalies in this chromosome that associate partial loss of its long arm with duplications in its short arm are uncommon. Only a few cases have been published and in most of them the reported patients present ovarian dysfunction, tall stature, and overdosage of the SHOX gene with locus Xp22.33. Considering these reports, we evaluated the case of a woman with a deletion in the long arm of the X chromosome, premature ovarian failure, tall stature, and multiple arterial vascular disease. With the aim to find a relationship between karyotype and phenotype, we explored associated anomalies in Xp and certified the overdosage of the SHOX gene in this case by MLPA. Also, taking into account the fact that the gene locus of the angiotensin-converting enzyme type 2 (ACE2) is located in Xp, our goal was to investigate the influence of this gene in the development of cardiovascular disease. The detection of the gene product of ACE2 by ELISA was undetectable. We have proposed that cytogenetic anomalies in X chromosome could contribute to decrease this protein synthesis in this gender.

Tempol attenuates atherosclerosis associated with metabolic syndrome via decreased vascular inflammation and NADPH-2 oxidase expression.

Oxidative stress is an important factor in the generation of vascular injury in atherosclerosis. Chronic administration of fructose in rodents is able to facilitate oxidative damage. In the present study we evaluated the role of Tempol, a superoxide dismutase mimetic, on the effect of high fructose intake in apolipoprotein E-deficient (ApoE-KO) mice. Rodents were fed with fructose overload (FF, 10% w/v) for 8 weeks and treated with Tempol 1 mg/kg/day the latest 4 weeks. Tempol revert the pro-oxidant effects caused by FF, diminished lipid peroxidation and impaired vascular NADPH oxidase system through the downregulation of p47phox expression in the vascular wall. Tempol inhibited the expression of vascular adhesion molecule 1 (VCAM-1) in aorta and reduced the development of atheroma plaques. Our results indicate that tempol attenuates oxidative stress by interfering with the correct assembly of Nox2 oxidase complex in the vascular wall and is able to reduce atherosclerosis. Thus tempol represents a potential therapeutic target for preventing risk factors associated with metabolic syndrome.

Role of Renin-Angiotensin system and oxidative stress on vascular inflammation in insulin resistence model.

(1) This study aims to demonstrate the causal involvement of renin angiotensin system (RAS) and oxidative stress (OS) on vascular inflammation in an experimental model of metabolic syndrome (MS) achieved by fructose administration to spontaneously hypertensive rats (FFHR) during 12 weeks. (2) Chronic treatment with candesartan (C) (10 mg/kg per day for the last 6 weeks) or 4OH-Tempol (T) (10(-3) mmol/L in drinking water for the last 6 weeks) reversed the increment in metabolic variables and systolic blood pressure. In addition, chronic C treatment reverted cardiovascular remodeling but not T. (3) Furthermore, chronic treatment with C was able to completely reverse the expression of NF-κB and VCAM-1, but T only reduced the expression. C reduced the expression of proatherogenic cytokines as CINC2, CINC3, VEGF, Leptin, TNF-alpha, and MCP-1 and also significantly reduced MIP-3, beta-NGF, and INF-gamma in vascular tissue in this experimental model. T was not able to substantially modify the expression of these cytokines. (4) The data suggest the involvement of RAS in the expression of inflammatory proteins at different vascular levels, allowing the creation of a microenvironment suitable for the creation, perpetuation, growth, and destabilization of vascular injury.

Effect of nebivolol on cardiovascular changes associated with a rat model of insulin-resistance.

Nebivolol is a vasodilator that combines beta-adrenergic blocking activity with a relaxant effect on vascular smooth muscle cells (VSMC) mediated by the endothelial nitric oxide (NO) pathway. FFR provide a model of dietary-induced insulin-resistance syndrome, which has been used to study the pathophysiological mechanisms associated with this syndrome. Our main objective was to examine the effect of long-term administration of nebivolol on metabolic and cardiovascular variables in fructose-fed rats (FFR), a model in which an altered bioavailability of NO has been already described. Male Wistar rats were randomly assigned to 4 groups (n = 8 each): I. Control (C); II. Control + nebivolol (C+N): 1 mg/kg(-1) x day(-1) in drinking water during the last 4 weeks. III. FFR: rats receiving fructose in drinking water as a 10% (w/v) solution during 8 weeks, and IV. FFR+N: idem II plus III. During the 8 weeks experimental period, variations in systolic blood pressure (SBP), glucose tolerance test (GTT) and plasma thiobarbituric acid-reactive substances (TBARS) were assessed. At the end of this experimental period, rats were killed and heart and kidneys were excised for calculation of relative heart weight (RHW) and histological evaluation of lumen to media ratio (L/M) in renal arteries. Rats from FFR group increased their SBP and RHW, showed glucose intolerance and an increment in lipid peroxidation. Moreover, FFR showed vascular remodeling in renal arteries evidenced by changes in L/M. Although the metabolic changes were not reverted by the administration of nebivolol, this drug successfully decreased SBP, TBARS levels and reverted structural changes such as cardiac hypertrophy and renal arterial remodeling. Data demonstrate that nebivolol administration could participate in the reversion of cardiovascular structural changes associated with the insulin-resistance syndrome.

Chronic administration of losartan reverses cardiovascular changes in hypertensive fructose-fed rats.

The cluster of risk factors including hyperinsulinemia, insulin resistance, hypertriglyceridemia and hypertension has been called syndrome X. Several evidences link the insulin resistance syndrome with endothelial dysfunction. Since the participation of the renin-angiotensin system (RAS) in this pathology is still unclear, the present study examined the effect of chronic administration of an angiotensin AT1 receptor antagonist, losartan (L), on endothelial nitric oxide synthase (eNOS) activity in aortic endothelium and cardiac tissue, and on the proliferation of primary cultured aortic smooth muscle cells (SMC), obtained from fructose-fed rats (FFR), an experimental model of syndrome X Male Wistar rats were used: Control, FFR and FFR+L (n = 8 in each group). After 8 weeks, tissue samples were obtained and 10% fetal calf serum (FCS) proliferative effect was examined in SMC by 3H-thymidine incorporation and cell counting. The eNOS activity was estimated in aortic endothelial lining and cardiac homogenates by conversion of 3H-arginine into 3H-citrulline. FFR aortic SMC showed a significantly increased 10% FCS-induced 3H-thymidine incorporation and cell number compared to controls. FFR aortic and cardiac eNOS activities were significantly decreased. Chronic treatment with L decreased systolic blood pressure,reverted cardiac hypertrophy, abolished the increased SMC proliferation and restoredeNOS activity. These data confirm that changes in SMC proliferation and endothelial dysfunction at different levels of the cardiovascular system are involved in syndrome "X", and that AT1 receptor blocking can revert those changes, suggesting an important role of the RAS, possibly mediated by AT2 receptors and kinins, in the physiopathological mechanisms of this model.

Proteoglycans production by aortic vascular smooth muscle cells from hypertensive rats

Remodeling of large and small arteries contributes to the development and complications of hypertension. Artery structural changes in chronic sustained hypertension include vascular smooth muscle cells (VSMC) proliferation and extracellular matrix (ECM) modifications. Extracellular constituents such as proteoglycans (PGs), may modulate vascular stiffness and VSMC growth and differentiation. We examined the effect of growth factors on secreted and membrane-bound PGs synthesis by cultured aortic smooth muscle cells (SMC) from 12- to 14- week-old spontaneously hypertensive rats (SHR) and age-matched Wistar rats. After stimulation with platelet-derived growth factor (PDGF-BB), 10% fetal calf serum (FCS) or 0.1% FCS as control, PGs synthesis (dpm/ng DNA) was evaluated in the medium (M-ECM) and in the cell layer (P-ECM) by a double-isotopic label method using both [3H]-glucosamine and [35S]-sodium sulfate which are incorporated into all complex carbohydrates or only into sulfated dysaccharides, respectively. Data are presented as percent of the control (0.1% FCS). SHR VSMC displayed a significantly greater synthesis of M-ECM [3H]-PGs than Wistar rat cells, with both treatments, but no differences in M-ECM [35S] uptake were found in any case. In the P-ECM, both PDGF-BB and 10% FCS produced a greater effect on [3H]-PGs and sulfated PGs synthesis in VSMC from SHR. An important change seen in SHR cells was a significant decreased sulfation, assessed by [35S]/[3H] ratio, in basal and stimulation conditions. Present results indicate the existence of changes in PGS synthesis and modulation in VSMC from a conduit-artery of SHR and support the pathophysiological role proposed for matrix proteoglycans in the vascular wall changes associated to hypertension and related vascular diseases as atherosclerosis.

Proteoglycans production by aortic vascular smooth muscle cells from hypertensive rats

Remodeling of large and small arteries contributes to the development and complications of hypertension. Artery structural changes in chronic sustained hypertension include vascular smooth muscle cells (VSMC) proliferation and extracellular matrix (ECM) modifications. Extracellular constituents such as proteoglycans (PGs), may modulate vascular stiffness and VSMC growth and differentiation. We examined the effect of growth factors on secreted and membrane-bound PGs synthesis by cultured aortic smooth muscle cells (SMC) from 12- to 14- week-old spontaneously hypertensive rats (SHR) and age-matched Wistar rats. After stimulation with platelet-derived growth factor (PDGF-BB), 10% fetal calf serum (FCS) or 0.1% FCS as control, PGs synthesis (dpm/ng DNA) was evaluated in the medium (M-ECM) and in the cell layer (P-ECM) by a double-isotopic label method using both [3H]-glucosamine and [35S]-sodium sulfate which are incorporated into all complex carbohydrates or only into sulfated dysaccharides, respectively. Data are presented as percent of the control (0.1% FCS). SHR VSMC displayed a significantly greater synthesis of M-ECM [3H]-PGs than Wistar rat cells, with both treatments, but no differences in M-ECM [35S] uptake were found in any case. In the P-ECM, both PDGF-BB and 10% FCS produced a greater effect on [3H]-PGs and sulfated PGs synthesis in VSMC from SHR. An important change seen in SHR cells was a significant decreased sulfation, assessed by [35S]/[3H] ratio, in basal and stimulation conditions. Present results indicate the existence of changes in PGS synthesis and modulation in VSMC from a conduit-artery of SHR and support the pathophysiological role proposed for matrix proteoglycans in the vascular wall changes associated to hypertension and related vascular diseases as atherosclerosis. (AU)

Aortic smooth muscle cell proliferation and endothelial nitric oxide synthase activity in fructose-fed rats.

The aim of this study was to evaluate the proliferative behavior of vascular smooth muscle cells in primary culture (pC-SMC) and the endothelial nitric oxide synthase (eNOS) activity in the endothelial lining of the aorta of fructose-fed rats (FFR). This is an experimental model of syndrome X, a cluster of cardiovascular risk factors including hyperinsulinemia, insulin resistance, and hypertension that has been suggested to be of pathophysiologic importance for the development of atherosclerosis. Male Wistar rats were used: Control (n = 12) and FFR (n = 12). After receiving fructose in drinking water (10% w/v) during 8 weeks, biochemical parameters, systolic blood pressure (SBP) and relative heart weight (RHW) were determined. The proliferative effect of 10% fetal calf serum (FCS) was examined in aortic pC-SMC by [3H]thymidine incorporation and by cell counting. Ca2+/calmodulin-dependent NOS activity was estimated in aortic endothelial lining and in heart tissue homogenates by conversion of [3H]arginine into [3H]citrulline. Fructose-fed rats showed hyperinsulinemia (P = .0263), altered glucose tolerance test (P < .001), higher SBP (P < .0001), and RHW (P = .0145), compared to control rats. These animals also showed an increase of 10% FCS-induced [3H]thymidine incorporation (P < .0001) and cell number of aortic pC-SMC (P = .0049) and decreased eNOS activity in both aortic endothelium (P = .0147) and cardiac tissue (P < .0001). These data support the hypothesis that syndrome X is associated to changes in SMC proliferation and endothelial dysfunction, which could be involved in the onset or progression of the atherogenic process.

Proteoglycan production by vascular smooth muscle cells from resistance arteries of hypertensive rats.

Extracellular matrix (ECM) modifications in the vascular wall contribute to the narrowing of arteries in hypertension. Because direct evidence for the role of proteoglycans (PGs) in the pathological process of resistance-sized arteries has not already been demonstrated, we examined the effect of growth factors on secreted and membrane-bound PG synthesis by cultured mesenteric vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) and Wistar rats. After 48 hours of stimulation with angiotensin II (Ang II), platelet-derived growth factor (PDGF-BB), and 10% fetal calf serum (FCS) or 0.1% FCS as control, PG synthesis (in dpm/ng DNA) was evaluated in the medium (M-ECM) and in the cell layer (P-ECM) by a double-isotopic label method with both [(3)H]-glucosamine and [(35)S]-sodium sulfate, which are incorporated into all complex carbohydrates or only into sulfated disaccharides, respectively. VSMC from SHR displayed a significantly lower level of synthesis of M-ECM [(3)H]-PGs than those of Wistar rats in all the experimental groups, including the control group (0. 1% FCS), but no differences in M-ECM [(35)S] uptake were found in any case. In the P-ECM, Ang II was the only factor that produced a lesser effect on [(3)H]-glucosamine and a greater effect on [(35)S]-sodium sulfate uptakes in VSMC from SHR than from Wistar rats. The most prominent change seen in VSMC from SHR was an increased sulfation, assessed by [(35)S]/[(3)H] ratio, in nonstimulated cells and in response to 10% FCS and Ang II but not to PDGF-BB compared with VSMC from Wistar rats. These data indicate the existence of changes in PG modulation in the resistance vessels of SHR, which suggests that PGs may contribute to the development of structural and functional modifications in hypertensive states.

Cardiovascular kinin-generating capability in hypertensive fructose-fed rats.

OBJECTIVE: The hypertensive state is often associated with metabolic abnormalities, including glucose intolerance. Tissue kallikrein, a potent kinin-generating enzyme, is present in the vascular wall and heart tissue. High dietary fructose consumption is reported to induce hyperinsulinemia, hypertriglyceridemia and hypertension. The objective of the present study was to examine the status of kallikrein in vascular and cardiac tissue from highly fructose-fed rats and to delineate the effect of kinins and the angiotensin converting enzyme inhibitor ramipril in this animal model of glucose intolerance. DESIGN AND METHODS: Male Wistar rats (350 g body weight) were divided into four groups of 10 rats each: (1) controls; (2) oral ramipril at 500 microg/kg per day for the last 2 study weeks; (3) fructose in drinking water as a 10% (w/v) solution for 4 weeks; and (4) fructose + ramipril, with fructose administered as in group 3 plus the administration of ramipril for the last 2 study weeks. Systolic blood pressure (tail-cuff method), glucose tolerance (2 g/kg body weight intraperitoneally) and metabolic parameters were recorded. Kallikrein activity in tail artery and heart tissue homogenates was estimated at the end of the 4th study week from measurements of kininogenase activity and kinins generated by a radioimmunoassay. RESULTS: The area under the curve for the glucose tolerance test increased from 1265 +/- 103 mmol/l after 120 min in the control and 1152 +/- 36 mmol/l in the ramipril group (NS) to 2628 +/- 143 mmol/l in the fructose group (P<0.01). The administration of ramipril to fructose-treated rats in group 4 improved glucose tolerance (2160 +/- 100 mmol/l; P<0.05 versus group 3). Blood pressure increased significantly in fructose-fed rats but fell markedly in fructose-fed rats treated with ramipril (P<0.01). Kallikrein activity measured in the heart and vessels increased as a consequence of fructose administration (P<0.05), but the administration of ramipril increased this parameter to a much greater extent (P<0.01 versus control group), which correlated closely with the decrease in blood pressure and the improvement in glucose tolerance observed in the fructose + ramipril group. CONCLUSIONS: The administration of fructose as a solution in the drinking water induced glucose intolerance and increased blood pressure. Treatment with the angiotensin converting enzyme inhibitor ramipril improved glucose tolerance and significantly diminished blood pressure. Cardiovascular kinin-generating capability increased in treated animals and this increase was even higher when rats were treated with ramipril, suggesting that kinins, acting as a paracrine hormonal system, can exert cardiovascular protection and contribute to the beneficial effects of angiotensin converting enzyme inhibitor.

Possible protective effects of kinins and converting enzyme inhibitors in cardiovascular tissues.

The main objective of this study was to determine if the components of the kallikrein-kinin system are released into the venous effluent from isolated perfused rat hearts. To assess the contribution of kinins and the vascular and cardioprotective effects of the ACE inhibitor ramipril, we determined the status of cardiac kallikrein (CKK), potent kinin-generating enzyme, in rats with right ventricular hypertrophy induced by chronic volume overload and left ventricular hypertrophy by aortic banding. CKK was measured as previously described (Nolly, H.L., Carbini, L., Carretero, O.A., Scicli, A.G., 1994). Kininogen by a modification of the technique of Dinitz and Carvalho (1963) and kinins were extracted with a Sep-Pak C18 cartridge and measured by RIA. CKK (169 +/- 9 pg Bk/30 min), kininogen (670 +/- 45 pg Bk/30 min) and immunoreactive kinins (62 +/- 10 pg Bk/30 min) were released into the perfusate. The release was almost constant over a 120 min period. Pretreatment with the protein synthesis inhibitor puromycin (10 mg i.p.) lowered the release of kallikrein (42 +/- 12 pg Bk/30 min, p < 0.001) and kininogen (128 +/- 56 pg Bk/30 min, p < 0.001). Addition of ramiprilat (10 micrograms/ml) increased kinin release from 54 +/- 18 to 204 +/- 76 pg Bk/30 min (p < 0.001). Aortic banding of rats increased their blood pressure (BP) (p < 0.001), relative heart weight (RHW) (p < 0.001) and CKK (p < 0.001). Ramipril treatment induced a reduction in BP (p < 0.05) and RHW (p < 0.005) while CKK remained elevated. Aortocaval shunts increased their ANF plasma levels (p < 0.05), RHW (p < 0.001) and CKK (p < 0.01). Ramipril treatment induced a reduction in RHW (p < 0.05), while CKK and ANF increased significantly (p < 0.05). The present data show that the components of the kallikrein-kinin system are continuously formed in the isolated rat heart and that ramipril reduces bradykinin breakdown with subsequent increase in bradykinin outflow. The experiments with aorta caval shunt and aortic banding show that cardiac tissues increase their kinin-generating activity and this was even higher in ramipril-treated animals. This may suggest that the actual level of kinins is finely tuned to the local metabolic demands. In this experimental model of cardiac hypertrophy. ACE inhibitors potentiate the actions of kinins and probably try to normalise endothelial cell function.

Efecto cardio y vasculoprotector de las kininas y los inhibidores de la enzima de conversión / Cardiovascular protective effect of kinins and converting enzyme inhibitors

ANTECEDENTES: Las kininas son oligopéptidos que generados localmente en corazón y vasos sanguíneos estimulan la producción endotelial de factores relajantes (prostaciclina, óxido nítrico y factor endotelial hiperpolarizante). El nivel de kininas depende de: a) la tasa de producción por kalikreínas y b) la tasa de destrucción por kininasas, entre las que se encuentra la enzima de conversión de angiotensina (CE). Los inhibidores de la enzima de conversión (CEI) empleados con notable éxito en el tratamiento de la hipertensión arterial y la insuficiencia cardíaca actuarían en parte prolongando la vida media del péptido. El objetivo de este trabajo es examinar: a) si los componentes del sistema kalikreína-kininógeno-kininas (SKKK) se liberan al perfusado en corazones aislados y perfundidos, b) la influencia de ramiprilat sobre la tasa de secreción de kininas y c) la acción biológica de las kininas en una preparación de vasos coronarios aislados. MATERIAL Y METODO: Los corazones de Ratas Wistar (300 ñ 30 gr) se aislaron y perfundieron en forma retrógrada con buffer Krebs-Henseleit equilibrado con 95 por ciento de oxígeno y 5 por ciento de anhídrido carbónico a un flujo constante (5 ml/min) mediante una bomba de perfusión Gilson. Kalikreína se midió por su capacidad de generar kininas; kininógeno, por una modificación de un método previamente descripto; y las kininas extraídas con un Set-Pack Cartridge, se dosaron por RIA. RESULTADOS: Los componentes del SKKK se forman y liberan continuamente en la preparación de corazón aislado (hasta 120 minutos). El pretratamiento con puromicina, un inhibidor de la síntesis proteica, descendió significativamente el release de kalikreína y kininógeno, confirmando la síntesis ex novo en el propio tejido cardíaco. El agregado del CEI, ramiprilat, incrementó significativamente el nivel de kininas en el perfusado. Kalikreína, per se, actuando sobre su sustrato en la propia pared del vaso libera kininas que relajan los vasos coronarios. Las kininas generadas permanentemente en la pared vascular en pequeñas cantidades se ponen de manifiesto en presencia de ramiprilat, relajando los vasos coronarios. El agregado de HOE 140, un inhibidor selectivo B2 de las kininas, bloquea el efecto relajante, confirmando que tanto la acción de las kalikreínas liberadas localmente como el efecto de los CEIs es mediado por kininas endógenas...

Kalikreína vascular y cardíaca en hipertensión asociada a alteraciones del metabolismo lipídico / Cardiovascular kallikrein in hypertension associated to lipidic metabolic disorders

ANTECEDENTES: La hipertensión arterial y la hiperlipemia dañan el endotelio vascular y predisponen al desarrollo de lesiones ateromatosas y enfermedades coronarias. Las células endoteliales y musculares son capaces de modular la función cardiovascular mediante la producción de factores autocrino/paracrinos. Se ha descripto la presencia de un sistema generador de kininas en vasos y corazón. El propósito de este estudio es examinar si existe modificación de la actividad kininogenásica en tejido cardiovascular de ratas dislipidémicas e hipertensas por inhibición de la producción del factor relajante derivado del endotelio. MATERIAL Y METODO: Se utilizaron ratas Wistar macho (430 ñ 50 g peso), las que se sometieron a los siguientes tratamientos: control (n= 10): dieta normal; lípidos (n= 10): dieta con sobrecarga de 16 por ciento de ácidos grasos saturados y 2 por ciento de colesterol durante 8 semanas; L-NAME (n= 10): administración oral de un inhibidor de la síntesis de factor relajante endotelial, L-nitro arginina metil éster, 100 mg/kg/ día durante las 2 últimas semanas del período experimental; lípidos + L-NAME (n= 10): administración de dieta con sobrecarga grasa durante 8 semanas y de L-NAME durante las 2 últimas semanas. Se midió la presión arterial, la concentración de lípidos plasmáticos y la actividad kininogenásica en homogenados de corazón y vasos sanguíneos (pgBK/mg/h). Resultados: La manipulación dietética de los animales no produjo cambios en su presión arterial, pero fue efectiva para instaurar un perfil lipoproteico aterogénico (p< 0,05). La administración de L-NAME produjo un aumento significativo de los niveles tensionales (p< 0,05), sin modificar las concentraciones de los metabolitos plasmáticos dosados. La actividad kininogenásica presente en homogenados de corazón aumentó significativamente en los animales sometidos a sobrecarga dietética de grasa y ese incremento fue aún mayor cuando se les adicionó al agua de bebida el inhibidor de la síntesis de factor relajante endotelial (p< 0,05). Un patrón semejante se observa en homogenados de aorta, arterias caudales y venas caudales (p< 0,05). CONCLUSIONES: El incrmento local de la capacidad generadora de kininas en tejido cardiovascular podría representar un esfuerzo tisular por contraponerse a la agresión endotelial causada por el aumento de los lípidos plasmáticos y el aumento de la presión arterial. Las kininas liberadas in situ tendrían efectos hemodinámicos y metabólicos ...

Efecto cardio y vasculoprotector de las kininas y los inhibidores de la enzima de conversión / Cardiovascular protective effect of kinins and converting enzyme inhibitors

ANTECEDENTES: Las kininas son oligopéptidos que generados localmente en corazón y vasos sanguíneos estimulan la producción endotelial de factores relajantes (prostaciclina, óxido nítrico y factor endotelial hiperpolarizante). El nivel de kininas depende de: a) la tasa de producción por kalikreínas y b) la tasa de destrucción por kininasas, entre las que se encuentra la enzima de conversión de angiotensina (CE). Los inhibidores de la enzima de conversión (CEI) empleados con notable éxito en el tratamiento de la hipertensión arterial y la insuficiencia cardíaca actuarían en parte prolongando la vida media del péptido. El objetivo de este trabajo es examinar: a) si los componentes del sistema kalikreína-kininógeno-kininas (SKKK) se liberan al perfusado en corazones aislados y perfundidos, b) la influencia de ramiprilat sobre la tasa de secreción de kininas y c) la acción biológica de las kininas en una preparación de vasos coronarios aislados. MATERIAL Y METODO: Los corazones de Ratas Wistar (300 ñ 30 gr) se aislaron y perfundieron en forma retrógrada con buffer Krebs-Henseleit equilibrado con 95 por ciento de oxígeno y 5 por ciento de anhídrido carbónico a un flujo constante (5 ml/min) mediante una bomba de perfusión Gilson. Kalikreína se midió por su capacidad de generar kininas; kininógeno, por una modificación de un método previamente descripto; y las kininas extraídas con un Set-Pack Cartridge, se dosaron por RIA. RESULTADOS: Los componentes del SKKK se forman y liberan continuamente en la preparación de corazón aislado (hasta 120 minutos). El pretratamiento con puromicina, un inhibidor de la síntesis proteica, descendió significativamente el release de kalikreína y kininógeno, confirmando la síntesis ex novo en el propio tejido cardíaco. El agregado del CEI, ramiprilat, incrementó significativamente el nivel de kininas en el perfusado. Kalikreína, per se, actuando sobre su sustrato en la propia pared del vaso libera kininas que relajan los vasos coronarios. Las kininas generadas permanentemente en la pared vascular en pequeñas cantidades se ponen de manifiesto en presencia de ramiprilat, relajando los vasos coronarios. El agregado de HOE 140, un inhibidor selectivo B2 de las kininas, bloquea el efecto relajante, confirmando que tanto la acción de las kalikreínas liberadas localmente como el efecto de los CEIs es mediado por kininas endógenas... (AU)

Kalikreína vascular y cardíaca en hipertensión asociada a alteraciones del metabolismo lipídico / Cardiovascular kallikrein in hypertension associated to lipidic metabolic disorders

ANTECEDENTES: La hipertensión arterial y la hiperlipemia dañan el endotelio vascular y predisponen al desarrollo de lesiones ateromatosas y enfermedades coronarias. Las células endoteliales y musculares son capaces de modular la función cardiovascular mediante la producción de factores autocrino/paracrinos. Se ha descripto la presencia de un sistema generador de kininas en vasos y corazón. El propósito de este estudio es examinar si existe modificación de la actividad kininogenásica en tejido cardiovascular de ratas dislipidémicas e hipertensas por inhibición de la producción del factor relajante derivado del endotelio. MATERIAL Y METODO: Se utilizaron ratas Wistar macho (430 ñ 50 g peso), las que se sometieron a los siguientes tratamientos: control (n= 10): dieta normal; lípidos (n= 10): dieta con sobrecarga de 16 por ciento de ácidos grasos saturados y 2 por ciento de colesterol durante 8 semanas; L-NAME (n= 10): administración oral de un inhibidor de la síntesis de factor relajante endotelial, L-nitro arginina metil éster, 100 mg/kg/ día durante las 2 últimas semanas del período experimental; lípidos + L-NAME (n= 10): administración de dieta con sobrecarga grasa durante 8 semanas y de L-NAME durante las 2 últimas semanas. Se midió la presión arterial, la concentración de lípidos plasmáticos y la actividad kininogenásica en homogenados de corazón y vasos sanguíneos (pgBK/mg/h). Resultados: La manipulación dietética de los animales no produjo cambios en su presión arterial, pero fue efectiva para instaurar un perfil lipoproteico aterogénico (p< 0,05). La administración de L-NAME produjo un aumento significativo de los niveles tensionales (p< 0,05), sin modificar las concentraciones de los metabolitos plasmáticos dosados. La actividad kininogenásica presente en homogenados de corazón aumentó significativamente en los animales sometidos a sobrecarga dietética de grasa y ese incremento fue aún mayor cuando se les adicionó al agua de bebida el inhibidor de la síntesis de factor relajante endotelial (p< 0,05). Un patrón semejante se observa en homogenados de aorta, arterias caudales y venas caudales (p< 0,05). CONCLUSIONES: El incrmento local de la capacidad generadora de kininas en tejido cardiovascular podría representar un esfuerzo tisular por contraponerse a la agresión endotelial causada por el aumento de los lípidos plasmáticos y el aumento de la presión arterial. Las kininas liberadas in situ tendrían efectos hemodinámicos y metabólicos ... (AU)

Enalapril: evaluación del efecto terapéutico / Enalapril: evaluation of therapeutic effect

Se comparó el efecto de una formulación farmacéutica de enalapril (ENA) con la del producto original (ORI) sobre la concentración de la enzima convertidora de angiotensina y la actividad de la renina plasmática en un grupo de voluntarios sanos y en un grupo de hipertensos, para validar su eficacia. A 5 voluntarios normotensos se les administró ENA durante 3 días y se determinó la concentración plasmática de la enzima convertidora de angiotensina y la actividad de renina plasmática a las 0, 5 y 53 horas. Esto se repitió a los 45 días pero con ORI. A 13 pacientes hipertensos esenciales se les determinó la concentración plasmática de la enzima convertidora de angiotensina y la actividad de renina plasmática basal y a la hora 1 y 4 de la administración de ENA. Luego se les administró ENA durante 90 días, al cabo de los cuales se repitieron los estudios iniciales. La actividad de la enzima convertidora de angiotensina disminuyó en los voluntarios con ambas formulaciones. Ante una dosis oral de ENA, los hipertensos descendieron sus niveles de la enzima convertidora de angiotensina y aumentaron los niveles de la actividad de renina plasmática. Las presiones sistólica y diastólica cayeron en los pacientes tratados con ENA durante 90 días con esfigmomanómetro. La presurometría ambulatoria mostró un descenso significativo de los valores tensionales diurnos y nocturnos, sin afectar el ritmo circadiano. Por lo tanto se considera que la utilización de ENA en la práctica clínica reproduce la eficacia del producto original

Enalapril: evaluación del efecto terapéutico / Enalapril: evaluation of therapeutic effect

Se comparó el efecto de una formulación farmacéutica de enalapril (ENA) con la del producto original (ORI) sobre la concentración de la enzima convertidora de angiotensina y la actividad de la renina plasmática en un grupo de voluntarios sanos y en un grupo de hipertensos, para validar su eficacia. A 5 voluntarios normotensos se les administró ENA durante 3 días y se determinó la concentración plasmática de la enzima convertidora de angiotensina y la actividad de renina plasmática a las 0, 5 y 53 horas. Esto se repitió a los 45 días pero con ORI. A 13 pacientes hipertensos esenciales se les determinó la concentración plasmática de la enzima convertidora de angiotensina y la actividad de renina plasmática basal y a la hora 1 y 4 de la administración de ENA. Luego se les administró ENA durante 90 días, al cabo de los cuales se repitieron los estudios iniciales. La actividad de la enzima convertidora de angiotensina disminuyó en los voluntarios con ambas formulaciones. Ante una dosis oral de ENA, los hipertensos descendieron sus niveles de la enzima convertidora de angiotensina y aumentaron los niveles de la actividad de renina plasmática. Las presiones sistólica y diastólica cayeron en los pacientes tratados con ENA durante 90 días con esfigmomanómetro. La presurometría ambulatoria mostró un descenso significativo de los valores tensionales diurnos y nocturnos, sin afectar el ritmo circadiano. Por lo tanto se considera que la utilización de ENA en la práctica clínica reproduce la eficacia del producto original (AU)

Vascular-derived kinins and local control of vascular tone.

The vascular wall itself, through a complex interplay of endocrine, neurocrine and autoparacrine mechanisms, plays an active role in vascular homeostasis. The endothelial cell senses humoral and hemodynamic changes and responds by secreting a variety of metabolically active substances that act locally causing either vasodilatation or vasoconstriction. Kallikrein (KK) and the mRNA for KK are present in arteries and veins. Vascular KK releases kinins from kininogen which circulate in plasma and is also present in vascular tissue. Vascular-derived kinins induce vasodilatation through the release of endothelial compounds (prostacyclin, EDRFs and cytochrome P-450). Disturbance in the delicate balance between vasodilators and vasoconstrictors may play a role in the development of hypertension. Vascular kallikrein (VKK) was significantly (P < 0.05) elevated after 2 weeks of development of renovascular and mineralocorticoid hypertension, and blood pressure was only slightly elevated. However, VKK decreased in both experimental models when blood pressure was increased. It is possible that the increase in VKK in the early stages resulted in increased local vasodilatory activity, thus counteracting the rise in blood pressure. As hypertension developed, KK was significantly decreased in arteries. The decrease in arterial KK during established hypertension is most likely secondary to high blood pressure. When the endothelium is damaged by high blood pressure, diabetes, excessive LDL cholesterol or cigarette smoking, a net imbalance favoring vasoconstriction, proliferation and migration of cells and increased lipid deposition predisposes to specific vascular diseases. Converting enzyme inhibitors (CEI) blunt the proliferative response of vascular smooth muscle cells after endothelial injury. The cardiovascular protective effects of CEI are mediated in part by the antihypertrophic, antihyperplastic and antithrombotic effects of kinins. The vascular kallikrein-kinin system has a promising role in the regulation of vascular homeostasis and some of the CEI effects may be explained by potentiation of the vascular-derived kinins.

Vascular-derived kinins and local control of vascular tone

The vascular itself, through a complex interplay of endocrine, neurocrine and autoparacrine mechanisms, plays an active role in vascular homeostasis. The endothelial cell senses humoral and hemodynamic changes and respondes by secreting a variety of metabolically active substances that act locally causing either vasodilatation or vasoconstriction. Kallikrein (KK) and the nRNA for KK are present in arteries and veins. Vascular KK releases Kinins from kininogen which circulate in plasma and is also present in vascular tissue. Vascular-derived kinins induce vasodilatation through the release of endothelial compounds ( prostacyclin, EDRFs and cytochrome P-450). Disturbance in the delicate balance between vasodilators and vasoconstrictiors may play a role in the development of hypertension. Vascular kallikrein (VKK) was significantly (P < 0.05) elevated after 2 weeks of development of renovascular and mineralocorticoid hypertension, and blood pressure was only slightly elevated. However, VKK decreased in both experimental models when blood pressure was incresed. It is possible that the increase in VKK in the early stages resulted in incresead local vasodilatory activity, thus counteracting the rise in blood pressure. As hypertension developed, KK was significantly decreased in arteries. The decrease in arterial KK during established hypertension is most likely secondary to high blood pressure....