Rosa Aras-López

Participation of Prostacyclin in Endothelial Dysfunction Induced by Aldosterone in Normotensive and Hypertensive Rats

The aim of the present study was to analyze the possible involvement of vasoconstrictors prostanoids on the reduced endothelium-dependent relaxations produced by chronic administration of aldosterone in Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). For this purpose, acetylcholine (ACh) relaxations in aortic segments from both strains were analyzed in absence and presence of the cyclooxygenase-1 (COX-1) and COX-2 inhibitor indomethacin, the specific COX-2 inhibitor NS-398, the TP receptor antagonist (SQ 29 548), the thromboxane A2 (TXA2) synthase inhibitor furegrelate, and the prostacyclin (PGI2) synthesis inhibitor tranylcypromine (TCP). In addition, COX-2 protein expression was studied by Western blot analysis. Release of prostaglandin E2 (PGE2) and the metabolites of PGF2α, TXA2, and PGI2, 13,14-dihydro-15-keto PGF2a, TXB2, and 6-keto-PGF1α, respectively, were measured. Treatment with aldosterone did not modify blood pressure levels in any strain. However, aldosterone markedly reduced (P<0.05) ACh-induced relaxations in segments from both strains in a similar extent. Indomethacin, NS-398, SQ 29 548, and TCP enhanced (P<0.05) ACh relaxations in both strains treated with aldosterone. Aortic COX-2 protein expression was higher in both strains of rats treated with aldosterone. In normotensive animals, aldosterone increases the ACh-stimulated aortic production of 13,14-dihydro-15-keto PGF2a, PGE2, and 6-keto-PGF1α (P<0.05). In SHR, ACh only increased the 6-keto-PGF1α production (P<0.05). It could be concluded that chronic treatment with aldosterone was able to produce endothelial dysfunction through COX-2 activation in normotensive and hypertensive conditions. PGI2 seems to be the main factor accounting for endothelial dysfunction in hypertensive rats, whereas other prostanoids besides PGI2 appear to be involved in endothelial dysfunction under normotensive conditions.

Aldosterone induces endothelial dysfunction in resistance arteries from normotensive and hypertensive rats by increasing thromboxane A2 and prostacyclin

The present study was designed to assess whether cyclooxygenase‐2 (COX‐2) activation is involved in the effects of chronic aldosterone treatment on endothelial function of mesenteric resistance arteries (MRA) from Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR).

Aldosterone increases RAMP1 expression in mesenteric arteries from spontaneously hypertensive rats.

OBJECTIVE We analysed the effect of aldosterone on calcitonin gene-related peptide (CGRP) mediated vasodilation in noradrenaline precontracted endothelium denuded mesenteric arteries segments from Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) and the effect of aldosterone on calcitonin receptor-like receptor (CL receptor) and receptor activity modifying protein 1 (RAMP1) expression in endothelium-denuded mesenteric arteries from SHR rats. RESULTS CGRP 0.1 nM-0.1 microM induced a concentration-dependent relaxation that was enhanced by aldosterone 1 microM in SHR only. Incubation with RU 486 10 microM significantly reduced the enhancement of CGRP-relaxation produced by aldosterone in SHR. CL receptor expression was not modified in either strain, while RAMP1 expression was enhanced in SHR by aldosterone 1 microM 120 min and 0.1 microM 120 min. This up-regulation of RAMP1 was prevented by RU 486 10 microM. CONCLUSIONS Aldosterone, through glucocorticoid receptor activation, increases the vasodilatory effect of CGRP in SHR mesenteric arteries, which seems to be mediated by increased RAMP1 expression.

Dexamethasone decreases neuronal nitric oxide release in mesenteric arteries from hypertensive rats through decreased protein kinase C activation

Neuronal NO plays a functional role in many vascular tissues, including MAs (mesenteric arteries). Glucocorticoids alter NO release from endothelium and the CNS (central nervous system), but no results from peripheral innervation have been reported. In the present study we investigated the effects of dexamethasone on EFS (electrical field stimulation)-induced NO release in MAs from WKY (Wistar-Kyoto) rats and SHRs (spontaneously hypertensive rats) and the role of PKC (protein kinase C) in this response. In endothelium-denuded MAs, L-NAME (NG-nitro-L-arginine methyl ester) increased the contractile response to EFS only in segments from SHRs. EFS-induced contraction was reduced by 1 micromol/l dexamethasone in segments from SHRs, but not WKY rats, and this effect was abolished in the presence of dexamethasone. EFS induced a tetrodotoxin-resistant NO release in WKY rat MAs, which remained unchanged by 1 micromol/l dexamethasone. In SHR MAs, dexamethasone decreased basal and EFS-induced neuronal NO release, and this decrease was prevented by the glucocorticoid receptor antagonist mifepristone. Dexamethasone did not affect nNOS [neuronal NOS (NO synthase)] expression in either strain. In SHR MAs, incubation with calphostin C (a non-selective PKC inhibitor), Gö6983 (a classic PKC delta and zeta inhibitor), LY379196 (a PKCbeta inhibitor) or PKCzeta-PI (PKCzeta pseudosubstrate inhibitor) decreased both basal and EFS-induced neuronal NO release. Additionally, PKC activity was reduced by dexamethasone. The PKC inhibitor-induced reduction in NO release was unaffected by dexamethasone. In conclusion, results obtained in the present study indicate that PKC activity positively modulates the neuronal NO release in MAs from SHRs. They also reveal that by PKC inhibition, through activation of glucocorticoid receptors, dexamethasone reduces neuronal NO release in these arteries.

Small Artery Remodeling in Obesity and Insulin Resistance

Microvascular abnormalities, both in function and structure, lead to impaired tissue perfusion that may affect multiple tissues and organs and seem to be involved in target-organ damage and complications observed in obesity and insulin resistance. In general, vascular remodeling of small arteries associated to cardiometabolic diseases seems to be hypertrophic and it is associated to increased extracellular matrix deposition, although specific vascular beds might show different structural patterns. The mechanisms by which obesity, insulin resistance and/or hyperinsulimemia determine vascular disease are not clear yet but might include hemodynamic factors such as hypertension, activation of the sympathetic nervous and the renin-angiotensin-aldosterone systems, metabolic factors such as insulin and advanced glycation end products and other factors such as adipokines, inflammation or oxidative stress. Exercise and weight loss as well as blockade of the renin-angiotensin system seem to be efficient actions to correct vascular alterations in patients. This review aims to examine the existing literature on structural alterations in small vessels associated to insulin resistance and obesity. A description about the underlying mechanisms possibly responsible of the vascular alterations is also provided. Moreover, effects of pharmacological and non pharmacological strategies that could modify these vascular alterations are summarized.

Ovariectomy increases the formation of prostanoids and modulates their role in acetylcholine-induced relaxation and nitric oxide release in the rat aorta

AIMS This study examines the effect of ovarian function on thromboxane A(2) (TXA(2)), prostaglandin (PG) I(2), PGF(2alpha), and PGE(2) release as well as the role of these substances in nitric oxide (NO) release and acetylcholine (ACh)-mediated relaxation. METHODS AND RESULTS Aortic segments from ovariectomized and control female Sprague-Dawley rats were used. Cyclooxygenase (COX-1 and COX-2) expression was studied. ACh-induced relaxation was analysed in the absence and presence of the COX-2 inhibitor NS-398, the TXA(2) synthesis inhibitor furegrelate, the PGI(2) synthesis inhibitor tranylcypromine (TCP), or the thromboxane-prostanoid receptor antagonist SQ-29548. TXA(2), PGI(2), PGF(2alpha), and PGE(2) release was measured, and the vasomotor effect of exogenous TXA(2), PGI(2,) PGF(2alpha), and PGE(2) was assessed. Basal and ACh-induced NO release in the absence and presence of NS-398, furegrelate, TCP, or TCP plus furegrelate was studied. Ovariectomy did not alter or increased COX-1 or COX-2 expression, respectively. NS-398 decreased, and furegrelate did not change, the ACh-induced relaxation in arteries from both groups. SQ29,548 decreased the ACh-induced relaxation only in aortas from ovariectomized rats. TCP decreased the ACh-induced relaxation in both groups, and furegrelate or SQ29,548 totally restored that response only in aortas from control rats. Ovariectomy increased the ACh-induced TXA(2), PGI(2), and PGE(2) release and the contractile responses induced by exogenous TXA(2), PGF(2alpha), or PGE(2), while it decreased the PGI(2)-induced vasodilator response. In aortas from control rats, NS-398 did not alter the ACh-induced NO release, and furegrelate, TCP, or TCP plus furegrelate increased that release. In arteries from ovariectomized rats, NS-398, furegrelate, TCP, or TCP plus furegrelate decreased the ACh-induced NO release. CONCLUSION Despite the prevalence of vasoconstrictor prostanoids derived from COX-2 in aortas from ovariectomized rats, the ACh-induced relaxation is maintained, probably as consequence of the positive regulation that prostanoids exert on eNOS activity.

Orchidectomy increases the formation of non-endothelial thromboxane A2 and modulates its role in the electrical field stimulation-induced response in rat mesenteric artery

The aim of this study was to analyze whether endogenous male sex hormones influence the release of thromboxane A2(TXA2) and its role in the electrical field stimulation (EFS)-induced response, as well as the mechanism involved. For this purpose, endothelium-denuded mesenteric arteries from control and orchidectomized male Sprague-Dawley rats were used to measure TXA2 release; EFS-induced response, nitric oxide (NO), norepinephrine (NA), and prostaglandin (PG) I2 release were also measured in the presence of the TXA2 synthesis inhibitor furegrelate. Orchidectomy increased basal and EFS-induced TXA2 release. Furegrelate decreased the EFS-induced contraction in arteries from control rats, but did not modify it in arteries from orchidectomized rats. The EFS-induced neuronal NO release and vasodilator response were increased by furegrelate in arteries from control rats, but were not modified in arteries from orchidectomized rats. Furegrelate did not modify the EFS-induced NA release or vasoconstrictor response in arteries from either control or orchidectomized rats. The EFS-induced PGI2 release was not modified by furegrelate in arteries from control rats, but was increased in arteries from orchidectomized rats. The results of the present study show that endogenous male sex hormone deprivation i) increases non-endothelial TXA2 release and ii) regulates the effect of endogenous TXA2 on the EFS-induced response through different mechanisms that, at the least, involve the NO and PGI2 systems. In arteries from control rats, inhibition of TXA2 formation decreases the EFS-induced response by increasing neuronal NO release. In arteries from orchidectomized rats, the EFS-induced response is unaltered after the inhibition of TXA2 formation, by increasing PGI2 release.

Lung hypoplasia in rats with esophageal atresia and tracheo–esophageal fistula

Introduction:Survivors of esophageal atresia and tracheo–esophageal fistula (EA-TEF) often suffer chronic respiratory tract disease. EA-TEF results from abnormal emergence of the trachea from the foregut. This study in a rat model tests the hypothesis that primary lung maldevelopment might be a downstream consequence of this defect.Results:The lung was hypoplastic in rats with EA-TEF although the histological pattern was normal. Maturation and arteriolar wall thickness were unchanged, but mesenchymal control of airway branching was weakened. This branching was deficient from embryonal day (E13) on in adriamycin-treated explants.Discussion:In conclusion, the lungs were hypoplastic in rats with experimental EA-TEF due to defective embryonal airway branching. However, arteriolar wall and respiratory epithelial patterns remained normal. These findings suggest that similarly defective lung development might contribute to chronic respiratory disease in EA-TEF patients.Methods:Pregnant rats received either 1.75 mg/kg i.p. adriamycin or vehicle on E7, E8, and E9. Lungs were recovered at E15, E18, and E2. Lung weight/body weight ratio, total DNA and protein, radial alveolar count, arteriolar wall thickness, lung maturity, and mesenchymal control of airway branching were assessed. E13 lungs were cultured for 72 h and explant airway branching was measured daily. For comparisons, nonparametric tests (*P < 0.05) were used.

The Myenteric Plexus of the Esophagus is Abnormal in an Experimental Congenital Diaphragmatic Hernia Model

BACKGROUND/AIM Infants surviving congenital diaphragmatic hernia (CDH) suffer from anatomical and functional esophageal abnormalities. Previous work in the nitrofen animal model of CDH demonstrated malformations in neural crest-derived structures, including the vagus and recurrent laryngeal nerves. The aim of the present study was to assess whether the esophageal myenteric plexus is abnormal in rats with CDH. METHODS We used the nitrofen-induced CDH fetal rat model. Two sections of the proximal, medium and distal esophagus from both groups were processed for immunohistochemical staining with anti-neuron specific enolase and anti-S-100 antibodies; the number of stained areas was recorded for each group. Whole-mount preparations of the entire esophagus of Control and CDH animals were histochemically stained for acetylcholinesterase; the density and area of the ganglia and the number of cells/ganglia were determined. Comparisons between groups were made by standard statistical methods. RESULTS The number of immunohistochemically stained areas in transversal sections were decreased in CDH animals for anti-enolase (11.5+/-6.06 vs. 1.93+/-1.49, control vs. CDH, p<0.001) and anti S-100 antibodies (8.57+/-4.1 vs. 4.06+/-2.82, p<0.001). In whole-mount preparations the number of ganglia per high power field (35.16+/-6.57 vs. 29.29+/-10.26, p<0.05), the number of cells per ganglia (11.85+/-3.52 vs. 2.28+/-4.61, p<0.0001) and the relative area of the ganglia (0.35+/-0.32 vs. 0.18+/-0.42%, p<0.001), were also significantly decreased in CDH animals compared with Controls. CONCLUSIONS Esophageal intrinsic innervation is defective in rat fetuses with CDH. If patients with CDH bear the same anomalies, this may explain some of their esophageal motility disorders. Finally, these findings support the concept of neural crest involvement in the pathogenic pathways of CDH.

Dexamethasone Decreases Contraction to Electrical Field Stimulation in Mesenteric Arteries from Spontaneously Hypertensive Rats through Decreases in Thromboxane A2 Release

Glucocorticoids play a role in the control of vascular smooth muscle tone through the alteration of vasoconstrictor and vasodilator factor production. We studied the effect of dexamethasone on vasoconstriction induced by electrical field stimulation (EFS) in rat mesenteric arteries (MAs) and the role of hypertension in this effect. Endothelium-denuded MAs were obtained from Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs). EFS response was analyzed by isometric tension recordings and cyclooxygenase (COX-1 and COX-2) expression by Western blot. Noradrenaline (NA) release was evaluated in segments incubated with [3H]NA. Dexamethasone (0.1 and 1 μM; 2–8 h) reduced vasoconstriction to EFS (200 mA, 0.3 ms, 1–16 Hz), in a dose- and time-dependent manner only in SHRs. However, the EFS-induced release of [3H]NA was increased in SHR arteries preincubated with dexamethasone (1 μM; 6 h). The thromboxane A2 (TxA2) synthase inhibitor furegrelate (10 μM), the selective COX-2 inhibitor NS-398 (N-[2-cyclohexyloxy-4-nitrophenyl] methanesulfonamide; 10 μM), or the TxA2 receptor antagonist SQ 29548 (1 μM), reduced EFS and NA induced vasoconstrictor responses. However, the effect of these drugs was abolished in arteries preincubated with dexamethasone. Both dexamethasone and phentolamine (1 μM) inhibited the increased thromboxane B2 levels observed after EFS. COX-2 protein expression was reduced by dexamethasone in SHR arteries. Results suggest that dexamethasone reduces vasoconstriction to EFS in MAs from SHRs by decreasing COX-2 expression, thereby decreasing the smooth muscle TXA2 release induced by α-adrenoceptor activation. The undetectable COX-2 expression in MAs from normotensive animals explains the noneffect of dexamethasone in their arteries.