Biomedical subjects

C F Sánchez-Ferrer

Publications and source records attributed to C F Sánchez-Ferrer.

At least 19 recordsLinked to original sources

PubMed2006

Pro-inflammatory effects of early non-enzymatic glycated proteins in human mesothelial cells vary with cell donor's age.

BACKGROUND AND PURPOSE: Diabetes mellitus is prevalent in the elderly population. It is also a disease causing tissue damage through several different mechanisms. Some of these mechanisms are also activated by ageing and this overlap raises questions about how diabetes induces damage in the elderly. Early products of non-enzymatic glycation of proteins (Amadori adducts), and the ageing process share the capacity to induce oxidative stress and inflammation in human peritoneal mesothelial cells (HPMCs). We have evaluated the interactions between the age of the donor of the HPMCs and the pro-inflammatory effects of Amadori adducts in those cells. EXPERIMENTAL APPROACH: HPMCs were isolated from 20 individuals (age range 21-81 years) and grown in culture. Using different experimental approaches we determined NF-kappaB dependent transcriptional activity and different NF-kappaB-related pro-inflammatory gene and protein expressions in basal (or non-stimulated) conditions and after stimulation with two Amadori adducts; highly-glycated haemoglobin and glycated bovine serum albumin. KEY RESULTS: Amadori-induced effects on NF-kappaB dependent-transcription and on the activity of NOS, COX and several NF-kappaB-related pro-inflammatory genes (iNOS, COX-2, TNF-alpha, IL-1beta, and IL6) diminished as the donor's age increased, being practically absent in cells from donors more than 65 years old. Such decreased effects were inversely correlated with an increased basal expression and activity of these pro-inflammatory markers with age. CONCLUSIONS AND IMPLICATIONS: Pro-inflammatory effects of Amadori-adducts in HPMCs were strongly dependent on cell donor's age. This may have significant implications for the mechanisms underlying diabetes-induced tissue damage in patients of different ages.

Adult↗

PubMed2006

Changes in the human peritoneal mesothelial cells during aging.

The number of older patients admitted to peritoneal dialysis (PD) programmes is growing. At the same time, there is increasing data about the role of mesothelial cells in determining the functional alteration of the peritoneum during PD. However, little is known about the functional changes accompanying the ageing process in mesothelial cells. We aimed to evaluate whether the aging process is accompanied by changes in some functional characteristic of the human peritoneal mesothelial cells (HPMC), which could account for the poor prognosis observed in old patients with PD. HPMCs were isolated from patients undergoing a nonurgent, nonseptic abdominal surgical procedure, without renal, vascular or inflammatory disease. Cytokine levels (by enzyme-linked immunosorbent assay (ELISA)), nitrates+nitrites, and cyclooxygenase (COX) activity (by a chemiluminescence assay), cytokines, COX, nitric oxide synthase (NOS), and nuclear factor (NF)-kappaB1, two messenger ribonucleic acid (mRNA) gene expressions (by reverse transcriptase (RT)-Multiplex PCR), COX, and NOS promoter gene activities, and NF-kappaB-dependent transcription (by transient transfection assays) were determined. Our data show a significant increase in cytokines, COX, and NOS activities, and mRNA expression of cytokines, COX-2, inducible nitric oxide synthase (iNOS) and precursors of NF-kappaB in HPMCs from old people. This was also the case for COX-2 and iNOS promoter gene activities and NF-kappaB-dependent transcription. There was a positive correlation between the age of the donor's cell and the proinflammatory profile of the HPMCs. Such age-dependent increase (around two-three times) is partially abolished by different antioxidant or free-radical scavengers. Thus, aging is accompanied by the presence of an inflammatory state in HPMCs, which involves the participation of different reactive oxygen species.

Adult↗

PubMed2003

Early and intermediate Amadori glycosylation adducts, oxidative stress, and endothelial dysfunction in the streptozotocin-induced diabetic rats vasculature.

AIMS/HYPOTHESIS: In a model of streptozotocin-induced Type 1 diabetes mellitus in rats of 9 weeks duration, we analysed time associations between the development of hyperglycaemia, early and intermediate glycosylation Amadori adducts, or AGE compared with enhancement of oxidative stress and endothelial dysfunction. METHODS: Endothelial function was tested at several stages of streptozotocin-induced diabetes and after treatment with insulin, resulting in different concentrations of blood glucose, glycosylated haemoglobin (an Amadori adduct), and AGE. Other animals were studied antagonising the formation of AGE with aminoguanidine. RESULTS: Relaxation in response to acetylcholine (1 nmol/l to 10 micro mol/l) was tested in isolated segments from aorta or mesenteric microvessels. Impairment of endothelium-dependent relaxations occurred after 2 weeks of untreated diabetes. Preincubation of vessels affected with 100 U/ml superoxide dismutase improved the relaxations to acetylcholine, along the time-course of the endothelial impairment. This indicates the participation of reactive oxygen species on diabetic endothelial dysfunction. The impairment of endothelium-dependent relaxations was recovered after 3 more weeks of insulin treatment. Aminoguanidine treatment did not modify this pattern of development. The time course of the rise and disappearance of endothelial dysfunction showed a higher correlation with glycosylated haemoglobin concentrations than with blood glucose or serum AGE. CONCLUSION/INTERPRETATION: Enhancement of early and intermediate Amadori adducts of protein glycosylation was the factor showing a better relation with the development of endothelium impairment. These results are consistent with a role for these products in the development of diabetic vasculopathy.

Acetylcholine↗

PubMed2001

High glucose induces cell death of cultured human aortic smooth muscle cells through the formation of hydrogen peroxide.

Alterations of the vessel structure, which is mainly determined by smooth muscle cells through cell growth and/or cell death mechanisms, are characteristic of diabetes complications. We analysed the influence of high glucose (22 mM) on cultured human aortic smooth muscle cell growth and death, as hyperglycaemia is considered one of the main factors involved in diabetic vasculopathy. Growth curves were performed over 96 h in medium containing 0.5% foetal calf serum. Cell number increased by 2 - 4 fold over the culture period in the presence of 5.5 mM (low) glucose, while a 20% reduction in final cell number was observed with high glucose. Under serum-free conditions, cell number remained constant in low glucose cultures, but a 40% decrease was observed in high glucose cultures, suggesting that high glucose may induce increased cell death rather than reduced proliferation. Reduced final cell number induced by high glucose was also observed after stimulation with 5 or 10% foetal calf serum. The possible participation of oxidative stress was investigated by co-incubating high glucose with different reactive oxygen species scavengers. Only catalase reversed the effect of high glucose. Intracellular H(2)O(2) content, visualized with 2',7'-dichlorofluorescein and quantified by flow cytometry, was increased after high glucose treatment. To investigate the cell death mechanism induced by high glucose, apoptosis and necrosis were quantified. No differences were observed regarding the apoptotic index between low and high glucose cultures, but lactate dehydrogenase activity was increased in high glucose cultures. In conclusion, high glucose promotes necrotic cell death through H(2)O(2) formation, which may participate in the development of diabetic vasculopathy.

Adult↗

PubMed2000

Enhancement of S-nitrosylation in glycosylated hemoglobin.

In this study, we report a novel differential nitric oxide interaction with nonglycosylated and glycosylated hemoglobin. After in vitro incubation of hemoglobin with S-nitroso N-acetyl penicillamine (SNAP), S-nitrosoglutathione, or S-nitrosocysteine, S-nitrosylation was significantly higher in human glycosylated hemoglobin purified from diabetic subjects compared to nondiabetic controls. Inversely, spontaneous decomposition was significantly lower for S-nitrosohemoglobin obtained from glycosylated hemoglobin. Bidimensional isoelectric focusing of hemoglobins incubated in vitro with SNAP also revealed a greater interaction of nitric oxide with glycosylated hemoglobin. In addition, a significantly higher level of S-nitrosohemoglobin was found in erythrocyte lysates from streptozotocin-induced diabetic rats compared to control rats. We suggest that highly glycosylated hemoglobin in diabetic subjects may favor S-nitrosylation, which may in turn impair vascular function, and participate in diabetic microangiopathy.

Analysis of Variance↗

PubMed2000

Highly glycated oxyhaemoglobin impairs nitric oxide relaxations in human mesenteric microvessels.

AIMS/HYPOTHESIS: It has been recently shown that glycated human haemoglobin induces endothelial dysfunction in rat vessels by generating superoxide anions that interfere with nitric oxide mediated responses. Our study analysed the effect of glycated human haemoglobin on the endothelium-dependent relaxations of human vessels. METHODS: Omental microvessels were obtained from patients (without diabetes, hypertension or vascular disease) during surgery and mounted in a small vessel myograph to study their vasoactive responses (vessels from 3-7 patients for each set of experiments). RESULTS: Cumulative vasodilatory responses to bradykinin (10 nmol/l to 3 mumol/l) were induced in vessels precontracted with 35-50 mmol/l potassium chloride. Addition of 100 mumol/l NG-nitro-L-arginine methyl ester reduced the relaxation evoked by bradykinin, but preincubation with both NG-nitro-L-arginine methyl ester and 10 mumol/l indomethacin was needed to abolish it. Bradykinin-induced responses were inhibited by 1 mumol/l non-glycated oxyhaemoglobin whereas no effect was obtained with 10 nmol/l oxyhaemoglobin. At these low concentrations (10 nmol/l), glycated human oxyhaemoglobin caused an impairment of bradykinin-induced relaxation when the percentage of glycation was 10% or higher. This effect was prevented by preincubating the vessels with ascorbic acid (10 mumol/l), superoxide dismutase (100 U/ml) and gliclazide (1 and 10 mumol/l), but not with indomethacin (10 mumol/l), catalase (400-600 U/ml), dimethylthiourea (1 mmol/l) or glibenclamide (10 mumol/l). In vessels preincubated with NG-nitro-L-arginine methyl ester (100 mumol/l), glycohaemoglobin did not add any additional effect. CONCLUSION/INTERPRETATION: Highly glycated human oxyhaemoglobin, at physiological plasmatic concentrations, impairs nitric oxide-mediated responses by a mechanism involving superoxide anions but not cyclooxygenase derivatives.

Animals↗

PubMed2000

Treatment with acarbose may improve endothelial dysfunction in streptozotocin-induced diabetic rats.

We sought to determine whether a single reduction of hyperglycemia and those derivatives from nonenzymatic protein glycosylation may be effective in reducing the development of diabetic endothelial dysfunction. Therefore, we investigated how acarbose, an inhibitor of intestinal alpha-glucosidase that reduce hyperglycemia by lowering glucose absorption, may prevent the impairment of acetylcholine (ACh)-induced endothelium-dependent relaxations observed in isolated vascular segments from untreated streptozotocin-induced diabetic rats. When administered after diabetes induction, 10 mg/kg acarbose decreased modestly the enhancement of blood glucose and glycosylated hemoglobin (HbA1c) levels, but not those of advanced glycosylation end products (AGEs). This effect was linked to a partial improvement of ACh-induced responses both in conductance vessels, such as aortic segments, and resistance vasculature, like mesenteric microvessels. When acarbose was introduced after 6 weeks of untreated diabetes, blood glucose, HbA1c, and AGE levels were not affected and endothelial dysfunction remained unchanged in mesenteric microvessels, whereas a small improvement was observed in aortic segments. The addition of 100 U/ml superoxide dismutase enhanced the impaired relaxations to values similar to vessels from nondiabetic rats, indicating a main role for superoxide anions in diabetes-induced endothelial dysfunction. We conclude that hyperglycemia itself or elevated HbA1c, but not plasma AGEs, are related to enhanced oxidative stress and to the impairment of endothelium function associated to diabetes. This process can be partially prevented by reducing glucose absorption with acarbose.

Acarbose↗

PubMed2000

Thapsigargin induces apoptosis in cultured human aortic smooth muscle cells.

Vascular remodeling is a key feature of many pathologic states, including atherosclerosis, or hypertension. Vascular smooth muscle cells participate in determining the vessel structure by several mechanisms such as cell migration, cell growth, or cell death (necrosis or apoptosis). Here we report that thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ -adenosine triphosphatase (ATPase), is able to induce apoptosis in human vascular smooth muscle cells (HVSMCs). Apoptosis was assessed by three different methods: differential chromatin binding dye staining. cytoplasmic histone-associated DNA fragments detection by enzyme-linked immunosorbent assay (ELISA) and terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). When HVSMCs were treated for 1 h with thapsigargin (100 nM-10 microM), there was a concentration-dependent increase in both parameters 24 h after the thapsigargin pulse. When a time-course experiment was performed, both parameters were significantly enhanced from 3 to 6 h after the exposure to thapsigargin. We conclude that thapsigargin promotes apoptosis in HVSMCs, providing a useful tool for the study of programmed cell death in human vascular smooth muscle.

Adult↗

PubMed1999

Pharmacological interference of vascular smooth muscle cell hypertrophy induced by glycosylated human oxyhaemoglobin.

Nonenzymatically glycosylated human oxyhaemoglobin induces vascular smooth muscle cell hypertrophy by releasing reactive oxygen species. We analysed the ability of drugs with antihypertrophic properties for the vascular wall and/or antioxidant activity, such as captopril, losartan, and nifedipine, or gliclazide, carvedilol, and ascorbic acid, to interfere with 10 nM glycosylated human oxyhaemoglobin-induced increase in vascular smooth muscle cell size (118+/-0.5% of basal). Vascular smooth muscle cell hypertrophy was abolished concentration-dependently, with pD(2) values over a 100-fold interval: 6.4+/-0.3, 7.7+/-0.4, 7.3+/-0.4, 7.4+/-0.6, 8. 8+/-0.2, and 9.0+/-0.2 for captopril, losartan, nifedipine, ascorbic acid, carvedilol and gliclazide, respectively. Drugs with powerful antioxidant properties, especially carvedilol and gliclazide, are particularly effective in preventing glycosylated human oxyhaemoglobin-induced vascular smooth muscle cell hypertrophy.

Animals↗

PubMed1998

Impairment of nitric oxide-mediated relaxations in anaesthetized autoperfused streptozotocin-induced diabetic rats.

This work was designed to determine in vivo the influence of the metabolic control of streptozotocin-induced diabetic rats, measured by the levels of haemoglobin glycosylation in blood (HbA1c), on developing vascular endothelial dysfunction. For this, the vasoactive responses to basal and stimulated endothelial nitric oxide (NO) were studied using the technique of the anaesthetized autoperfused rat, analyzing the responses to acetylcholine (ACh) and N(G)-nitro-L-arginine methyl ester (L-NAME) in non-diabetic and diabetic rats with different degrees of metabolic control (four groups with HbA1c levels of 5.5-7.4%, 7.5-9.4%, 9.5-12%, and >12%, respectively). When administered over a noradrenaline-induced vasopressor tone, ACh (0.25, 0.75, 2.5, 7.5 and 25 microg kg(-1)) induced dose-dependent vasodilatatory responses in all rat groups, reducing both mean arterial pressure and perfusion pressure of the left hindlimb. These responses were similar in non-diabetic and in diabetic rats with good metabolic control (HbA1c 5.5-7.4%), while diabetic rats with levels of HbA1c higher than 7.5% showed significantly lower vasodilatatory responses to ACh. In untreated diabetic rats, the relaxant responses evoked by the NO donor sodium nitroprusside were also impaired. On the other hand, increasing doses of L-NAME (0.1 to 10 mg kg(-1)) enhanced both mean arterial pressure and left hindlimb perfusion pressure in diabetic and non-diabetic rats. As with ACh, the responses to L-NAME were significantly reduced in diabetic rats with HbA1c levels higher than 7.5%. To determine the mechanism underlying the NO-mediated endothelial dysfunction, the responses to ACh in untreated diabetic rats (HbA1c >12%) were studied in the presence of the NO substrate L-arginine, in the presence of the oxygen-derived free radical scavenger superoxide dismutase (SOD), or in the presence of both compounds. Both L-arginine and SOD produced a partial improvement of the ACh-induced vasodilatatory responses, but the effects of these agents were not additive. In this group of animals, SOD also induced a partial recovery of the L-NAME-evoked vasoconstrictions. In non-diabetic and untreated diabetic rats, the plasma levels of NO derivatives and arginine were measured. No significant differences were obtained in the amount of nitrites plus nitrates, while plasma levels of arginine were markedly reduced in the untreated diabetic animals. The results indicate that the endothelial dysfunction associated to diabetes is closely related to the level of metabolic control of the disease. Therefore, it is possible to establish a threshold for developing endothelium impairment from percentages of HbA1c higher than 7.5%. As the responses to the NO synthase blocker L-NAME were analogously impaired, it is reasonable to suggest that diabetic endothelial dysfunction is related to the interference with mechanisms linked both to stimulated and basal production of NO. We suggest that this interference is partially due to a deficit in the substrate availability for NO and to an increased generation of superoxide anions.

Acetylcholine↗

PubMed1998

Endothelial dysfunction and metabolic control in streptozotocin-induced diabetic rats.

1. The aim of this work was to study the influence of the metabolic control, estimated by the levels of glycosylated haemoglobin in total blood samples (HbA1c), in developing vascular endothelial dysfunction in streptozotocin-induced diabetic rats. Four groups of animals with different levels of insulin treatment were established, by determining HbA1c values in 5.5 to 7.4%, 7.5 to 9.4%, 9.5 to 12% and > 12%, respectively. 2. The parameters analysed were: (1) the endothelium-dependent relaxations to acetylcholine (ACh) in isolated aorta and mesenteric microvessels; (2) the vasodilator responses to exogenous nitric oxide (NO) in aorta: and (3) the existence of oxidative stress by studying the influence of the free radical scavenger superoxide dismutase (SOD) on the vasodilator responses to both ACh and NO. 3. In both isolated aortic segments and mesenteric microvessels, the endothelium-mediated concentration-dependent relaxant responses elicited by ACh were significantly decreased when the vessels were obtained from diabetic animals but only with HbA1c values higher than 7.5%. There was a high correlation between HbA1c levels and the impairment of ACh-induced relaxations, measured by pD2 values. 4. The concentration-dependent vasorelaxant responses to NO in endothelium-denuded aortic segments were significantly reduced only in vessels from diabetic animals with HbA1c values higher than 7.5%. Again, a very high correlation was found between the HbA1c values and pD2 for NO-evoked responses. 5. In the presence of SOD, the responses to ACh or NO were only increased in the segments from diabetic rats with HbA1c levels higher than 7.5%, but not in those from non-diabetic or diabetic rats with a good metabolic control (HbA1c levels <7.5%). 6. These results suggest the existence of: (1) a close relation between the degree of endothelial dysfunction and the metabolic control of diabetes, estimated by the levels of HbA1c; and (2) an increased production of superoxide anions in the vascular wall of the diabetic rats, which is also related to the metabolic control of the disease.

Acetylcholine↗

PubMed1998

Vascular smooth muscle cell hypertrophy induced by glycosylated human oxyhaemoglobin.

1. Nonenzymatic protein glycosylation is a possible mechanism contributing to oxidative stress and vascular disease in diabetes. In this work, the influence of 14%-glycosylated human oxyhaemoglobin (GHHb), compared to the non-glycosylated protein (HHb), was studied on several growth parameters of rat cultured vascular smooth muscle cells (VSMC). A role for reactive oxygen species was also analysed. 2. Treatment of VSMC for 48 h with GHHb, but not with HHb, increased planar cell surface area in a concentration dependent manner. The threshold concentration was 10 nM, which increased cell size from 7965+/-176 to 9411+/-392 microm2. Similarly, only GHHb enhanced protein content per well in VSMC cultures. 3. The planar surface area increase induced by 10 nM GHHb was abolished by superoxide dismutase (SOD; 50 200 u ml(-1)), deferoxamine (100 nM-100 microM), or dimethylthiourea (1 mM), while catalase (50 200 u ml(-1)) or mannitol (1 mM) resulted in a partial inhibition of cell size enhancement. 4. When a known source of oxygen free radicals was administered to VSMC, the xanthine/xanthine oxidase system, the results were analogous to those produced by GHHb. Indeed, enhancements of cell size were observed, which were inhibited by SOD, deferoxamine, or catalase. 5. These results indicate that, at low concentrations, GHHb induces hypertrophy in VSMC, this effect being mediated by superoxide anions, hydrogen peroxide, and/or hydroxyl radicals. Therefore, glycosylated proteins can have a role in the development of the structural vascular alterations associated to diabetes by enhancing oxidative stress.

Animals↗

PubMed1998

Endogenous angiotensin II and cell hypertrophy in vascular smooth muscle cultures from hypertensive Ren-2 transgenic rats.

We investigated the possible role of a tissular renin-angiotensin system in promoting the growth of vascular smooth muscle cells (VSMCs) from hypertensive transgenic rats (TGRs) with the mouse renin gene Ren-2. Mean arterial pressure values were 99.4 +/- 2.8 and 186.7 +/- 5.0 mm Hg for control Sprague-Dawley rats (SDs) and TGRs, respectively (p < 0.05). The tunica media of femoral arteries obtained from hypertensive TGRs was found to be thickened compared to that of age-matched normotensive SDs. Angiotensin II could be detected by dot blot and immunocytochemistry and quantified by radioimmunoassay in transgenic VSMCs, but not in control SD ones. Under serum-free conditions, VSMCs derived from TGRs showed a higher protein content than those derived from SDs (337 +/- 19 vs. 269 +/- 14 pg/cell, p < 0.05, n = 3). Under the same basal conditions, the mean planar cell surface area was significantly higher in TGR VSMCs than in SD ones (4,764 +/- 204 vs. 4,074 +/- 238 micron 2, p < 0.05). In addition, TGR VSMCs showed an enhanced [14C]-leucine uptake but SD VSMCs did not (13,188 +/- 663 vs. 7,633 +/- 713 dpm/well, p < 0.05). VSMCs showed a concentration-dependent proliferative response to fetal calf serum (FCS) that was more marked in TGRs than in SDs. In the absence of FCS, c-fos and c-jun mRNAs were expressed only in transgenic cultures. From the present results, we can hypothesize that cultured TGR VSMCs are able to synthesize angiotensin II that, being almost exclusive into the cells, contributes to produce VSMC growth in the absence of FCS stimulation.

Angiotensin II↗

PubMed1998

Endothelial factors and autoregulation during pressure changes in isolated newborn piglet cerebral arteries.

To analyze newborn cerebrovascular autoregulation, middle cerebral arteries from 3-4-d-old piglets were cannulated, and diameter changes after transmural pressure variation were measured. After an equilibration period at 30 mm Hg, pressure was modified from 10 to 70 mm Hg in 20-mm Hg steps. Segments with endothelium showed vasodilation during pressure decrease and vasoconstriction during pressure increase. In each case the maximum response was about 5% that of the resting diameter. Segments without endothelium responded passively to pressure change. Vasodilation during pressure decrease was reduced by the preferential calcium-activated potassium (KCa) channel blocker, tetraethylammonium (1 mM), and was absent with the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methylester (L-NAME, 10 microM). The NO synthase substrate, L-arginine (10 microM), counteracted the dilation blockade caused by L-NAME. The cyclooxygenase inhibitor indomethacin (10 microM) and the endothelin A receptor antagonist BQ-123 (10O microM) eliminated the pressure increase-induced vasoconstriction. The ATP-sensitive potassium channel blocker, glibenclamide (1 microM), and the endothelin B receptor antagonist, BQ-788 (10 nM), did not modify the autoregulatory response. None of these drugs modified the passive changes produced by pressure variations in segments without endothelium. These results suggest that: 1) piglet middle cerebral artery autoregulation is endothelium-dependent; 2) NO and KCa channels are involved in vasodilation during transmural pressure decrease, and 3) endothelin-1, through endothelin A receptors, and prostanoids mediate vasoconstriction during pressure increase.

Animals↗

PubMed1997

Angiotensin II mediates cell hypertrophy in vascular smooth muscle cultures from hypertensive Ren-2 transgenic rats by an amiloride- and furosemide-sensitive mechanism.

We have reported that cultured vascular smooth muscle cells (VSMC) from hypertensive Ren-2 transgenic rats (TGR) are constitutively hypertrophic when compared to matched cells from normotensive Sprague-Dawley rats (SD), by a mechanism involving the endogenous production of angiotensin II (AII). In the present work, we analyzed the possible involvement of two Na+ transport mechanisms in TGR-VSMC hypertrophy. In both SD- and TGR-VSMC, AII increased both cell size, by a furosemide- and amiloride-sensitive mechanism, and Na+/K+/2Cl- cotransport activity, by an amiloride-sensitive mechanism. Under basal unstimulated conditions, TGR-VSMC showed higher cell size and Na+/K+/2Cl- cotransport activity than SD-VSMC. Under these same conditions, losartan, furosemide, or amiloride reduced cell size only in TGR-VSMC. Similarly, basal cotransport activity was reduced by losartan and amiloride to levels similar to those observed in SD-VSMC. We conclude that hypertrophy of TGR-VSMC is dependent on the endogenous production of AII and mediated by increased Na(+)-H+ exchange and Na+/K+/2Cl- cotransport activities.

Angiotensin II↗

PubMed1997

Nifedipine, losartan and captopril effects on hyperplasia of vascular smooth muscle from Ren-2 transgenic rats.

Vascular smooth muscle cells from hypertensive transgenic rats for the mouse Ren-2 gene exhibited radioimmunoassayable angiotensin II and hyperplasia in comparison with cells from Sprague-Dawley rats. However, neither captopril, losartan, saralasin, nor PD123319 (all at 10 microM) modified DNA synthesis or cell number observed in 4-day growth curves with 10% fetal calf serum. Nifedipine reduced DNA synthesis in both cell types, the concentration required being significantly higher in Sprague-Dawley- (1 microM) than in transgenic-derived cultures (100 nM). The EC50 values were of 2.43 +/- 0.32 and 1.0 +/- 0.17 microM, respectively (P < 0.05). In both cell types, only 10 microM nifedipine reduced serum-induced cell proliferation, but inhibition percentage was higher in transgenic-derived cultures. In conclusion, hyperplasia of transgenic-derived vascular smooth muscle cells is not blocked by angiotensin-converting enzyme inhibitors or angiotensin receptor antagonists, but these cells are more sensitive to the antiproliferative effects of nifedipine.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1997

Effects of captopril, losartan, and nifedipine on cell hypertrophy of cultured vascular smooth muscle from hypertensive Ren-2 transgenic rats.

1. We hypothesized that tissular renin-angotensin system (RAS) induces vascular hypertrophy in hypertensive Ren-2 transgenic rats (TGR; strain name TGR(mRen2)L27). This assumption was tested in cell cultures of vascular smooth muscle (VSMC) from both hypertensive TGR and control normotensive Sprague-Dawley (SD) rats. Planar cell surface area, protein synthesis, and protein content per cell were studied, the role for locally produced angiotensin II (AII) was evaluated and the possible pharmacological interference by different drugs was analysed. 2. By use of radioimmunoassay techniques, AII could be determined in TGR cultures (10.25 +/- 0.12 pg per 10(7) cells) while it could not be detected in SD ones. 3. Under serum-free conditions, VSMC from hypertensive TGR were hypertrophic when compared to SD VSMC, as they presented a higher protein content per cell (335 +/-18 and 288 +/- 7 pg per cell respectively; P<0.05) and increased mean planar cell surface area, as determined by image analysis (4,074 +/- 238 and 4,764 +/- 204 microm2, respectively; P < 0.05). 4. When exogenously added to cultured SD and TGR VSMC, AII (100 pM to 1 microM) promoted protein synthesis and protein content in a concentration-dependent manner without affecting DNA synthesis. Maximal effects were observed at 100 nM. At this concentration, AII effectively increased planar cell surface area in both SD and TGR cultures by approximately 20%. 5. Treatment of TGR cultures, in the absence of exogenous AII, with the angiotensin-converting enzyme inhibitor captopril or the angiotensin AT1 receptors antagonist losartan (100 nM to 10 microM) reduced planar cell surface area in a concentration-dependent manner. In addition, both captopril and losartan (10 microM), decreased protein synthesis by approximately 15%. 6. Treatment of SD VSMC, in the absence of exogenous AII, with both captopril and losartan had no effect either on planar cell surface area or protein synthesis. 7. Treatment with the Ca2+ antagonist nifedipine (100 nM to 10 microM) reduced cell size in both SD and TGR cultures. Maximal cell reduction reached by nifedipine averaged 906 +/- 58 and 1,292 +/- 57 microm2, in SD and TGR, respectively (P<0.05). In addition, nifedipine, nitrendipine and nisoldipine (all at 10 microM) decreased protein synthesis in both cell types by 15-25%. 8. We concluded that cultured VSMC from TGR are hypertrophic in comparison with those from SD. This cell hypertrophy can be the consequence of the expression of the transgene Ren-2 that activates a tissular RAS and locally produces AII, which acts in a paracrine, autocrine, or intracrine manner. Cell hypertrophy in TGR cultures could be selectively reduced by RAS blockade, while nifedipine decreased cell size and protein synthesis in both hypertrophic and non hypertrophic cells.

Angiotensin II↗

PubMed1996

Effect of ageing and hypertension on endothelial modulation of ouabain-induced contraction and sodium pump activity in the rat aorta.

OBJECTIVE: To investigate the endothelial modulation of the rat thoracic aorta sodium-potassium ATPase activity and its possible alteration by ageing and hypertension. METHODS: Male spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) aged 5 weeks, 3, 6, 12 and 18 months were anaesthetized. Their aortae were dissected and divided into cylindrical segments and vasomotor responses obtained in segments with or without endothelium were recorded on a polygraph. RESULTS: Endothelium removal increased ouabain responses in young (aged 3 and 6 months) WKY rat aortic segments, but reduced those obtained in old (aged 18 months) WKY rat segments and in segments from SHR aged 3, 6 and 12 months. An enhancement of contractions in response to ouabain with age was observed in both strains, but it occurred at earlier ages in vessels from SHR. At ages 3 and 6 months, responses to ouabain were higher in intact vessels from SHR than they were in those from WKY, but were lower in endothelium-denuded vessels. In aortic segments from 6-month-old WKY rats and SHR, ouabain reduced or abolished potassium-induced relaxations in segments with or without endothelium, respectively. In vessels from SHR and WKY rats aged 18 months, ouabain abolished potassium-induced relaxations both in intact and in endothelium-denuded vessels. CONCLUSIONS: Endothelium of WKY rat aorta might release a factor in response to ouabain that modulates its contraction negatively. Endothelium of SHR and old WKY rat aorta releases a contracting factor that modulates ouabain contractions positively. Thus, the inhibitory effect of endothelium on contractions induced by ouabain might be lost as a consequence both of hypertension and of age, being replaced by an endothelium-dependent contracting factor that facilitates ouabain responses.

Aging↗