Addition of lysophosphatidic acid (LPA) to rat aorta-derived endothelial cells significantly induced preproendothelin-1 (preproET-1) mRNA expression. PreproET-1 mRNA levels reached a plateau within 1 h after the addition of 0.5 μM LPA and declined after 2 h. The induction was superinduced by cycloheximide and was blocked by actinomycin D. Suramin, an LPA receptor antagonist, abolished the induction of preproET-1 mRNA by LPA. Protein kinase C inhibitors, H7 and bisindolylmaleimide, were able to block the induction. Transient transfection experiment revealed that the elevated preproET-1 mRNA was a result of the activation of ET-1 gene activity. Electrophoretic mobility shift assay revealed that LPA stimulated the binding of AP-1. The secreted level of ET-1 was elevated 2.3-fold after 12 h of stimulation with LPA. Our results suggest that the upregulation of preproET-1 by LPA may serve to augment and prolong the vasoconstriction action of LPA.

Thromboxane A2 (TXA2) and ET-1 have been known to play important roles in modulating vascular contraction and growth. The present study was undertaken to examine the effect of TXA2 on the induction of endothelin-1 (ET-1) mRNA and protein levels in smooth muscle cells derived from rat heart. U-46619, a stable TXA2 mimetic, superinduced preproET-1 mRNA in the presence of cycloheximide in these cells. This effect could be blocked by SQ-29548, a TXA2/prostaglandin H2 receptor antagonist and by actinomycin D, an RNA synthesis inhibitor. In addition, H7, a protein kinase C inhibitor, could abolish the induction. Transient transfection experiment revealed that the elevated ET-1 mRNA level after U-46619 treatment was a result of the activation of ET-1 gene activity. The elevated ET-1 message level was accompanied by increased ET-1 release into the cultured medium. These results show that the short-lived TXA2 can induce potent and long-lived ET-1. These findings support a potential role for ET-1 in the pathogenesis of coronary atherosclerosis and hypertension evoked by TXA2.

No description available.

no / Prolonged hyperglycaemia impairs vascular reactivity and inhibits voltage-activated K+ (Kv) channels. We examined acute effects of altering glucose concentration on the activity and inhibition by endothelin-1 (ET-1) of Kv currents of freshly isolated rat arterial myocytes. Peak Kv currents recorded in glucose-free solution were reversibly reduced within 200 s by increasing extracellular glucose to 4 mm. This inhibitory effect of glucose was abolished by protein kinase C inhibitor peptide (PKC-IP), and Kv currents were further reduced in 10 mm glucose. In current-clamped cells, membrane potentials were more negative in 4 than in 10 mm glucose. In 4 mmd-glucose, 10 nm ET-1 decreased peak Kv current amplitude at +60 mV from 23.5 ± 3.3 to 12.1 ± 3.1 pA pF−1 (n = 6, P < 0.001) and increased the rate of inactivation, decreasing the time constant around fourfold. Inhibition by ET-1 was prevented by PKC-IP. When d-glucose was increased to 10 mm, ET-1 no longer inhibited Kv current (n = 6). Glucose metabolism was required for prevention of ET-1 inhibition of Kv currents, since fructose mimicked the effects of d-glucose, while l-glucose, sucrose or mannitol were without effect. Endothelin receptors were still functional in 10 mmd-glucose, since pinacidil-activated ATP-dependent K+ (KATP) currents were reduced by 10 nm ET-1. This inhibition was nearly abolished by PKC-IP, indicating that endothelin receptors could still activate PKC in 10 mmd-glucose. These results indicate that changes in extracellular glucose concentration within the physiological range can reduce Kv current amplitude and can have major effects on Kv channel modulation by vasoconstrictors.

No description available.

No description available.

Endocardial endothelial cells (EECs) can exert a significant influence on cardiac function by releasing various factors such as nitric oxide (NO), prostanoids, endothelin-1 (ET-1) and angiotensin II (Ang II). Recently, results obtained in our laboratory demonstrated the presence of NPY and its receptors, Y[subscript 1] and Y[subscript 2], as well as ET-1 and its receptors, ET[subscript A] and ET[subscript B], at the level of endocardial endothelial cells (EECs). We have also shown that NPY induces a sustained rise in the intracellular calcium level of these cells, and that only right ventricular EECs have the capacity of secreting NPY. Moreover, the evidence in the literature has become plentiful about complex interactions existing between ET-1 and other cardioactive mediators, such as NO and Ang II. Based on the above-mentioned data, the objective of this study was to investigate if a dialogue equally exists between the systems of NPY and ET-1 at the level of human right (hREECs) and left (hLEECs) ventricular EECs. Using the technique of indirect immunofluorescence coupled to 3-D confocal microscopy, as well as ELISA, our results show that increasing concentrations of NPY (10[superscript -15], 10[superscript -10] and 10[superscript -5]M) induce the release of ET-1 from REECs and LEECs in a time- and dose-dependent fashion. However, right ventricular EECs seem to have a higher ET-1 secretory capacity as compared to their left counterparts. Upon the use of selective antagonists for the NPY receptors, Y[subscript 1], Y[subscript 2] and Y[subscript 5], and the ET-1 receptors, ET[subscript A] and ET[subscript B], our results demonstrated that in REECs the NPY-induced release of ET-1 seems to be primarily due to Y[subscript 2] receptor activation, with the subsequent activation of the ET[subscript A] and ET[subscript B] receptors by the released ET-1. On the other hand, in LEECs, the NPY-evoked secretion of ET-1 seems to be mainly the result of Y[subscript 5] receptor activation by NPY. Unlike REECs, the ET-1 released by NPY in this type of cells does not seem to be contributing further to its own release by activation of its ET[subscript A] and ET[subscript B] receptors. Therefore, our results suggest that NPY is a regulator of ET-I secretion at the level of human EECs, and that this secretory process of ET-1 is different between the right and left ventricular cells. Moreover, these results serve to highlight and endorse the important sensory and tuning roles that right and left ventricular EECs possess, respectively. The ability of EECs to contribute to the local as well as systemic release of factors, such as NPY and ET-1, can affect not only the excitation-secretion coupling of EECs and the excitation-contraction coupling of cardiomyocytes, but also the physiological and pathophysiological state of the underlying, heart muscle.

L’endothéline-1 (ET-1) est un puissant agent vasoconstricteur dont la production est dérégulée dans plusieurs maladies inflammatoires où l’expression des cyclooxygénases-1/2 (COX-1/2) est augmentée. Puisqu’il est connu que la voie p38 MAPK est impliquée dans la régulation de l’ET-1 au niveau de l’ARNm, nous avons étudié le rôle de l’un de ses substrats, la kinase MK2 dans la régulation post-transcriptionnelle de l’ET-1 et des COX. Pour ce faire, nous avons utilisé des souris MK2-déficientes (MK2-/-) ainsi que des contrôles (MK2+/+) issus de la même portée. Des paramètres de la fonction cardiaque ont été mesurés sous anesthésie à l’aide d’un cathéter Millar et la réactivité vasculaire de l’artère fémorale a été mesurée par myographe. L’expression de ET-1, COX-1 et COX-2 a été quantifiée dans la cellule endothéliale aortique (CE) par qPCR. En réponse à l’ET-1 (100 nM), l’expression de la préproET-1 dans les CE augmente en fonction du temps (p<0.05) : cette variation est accentuée chez les souris MK2-/-. Bien que la pression artérielle soit similaire entre les souris MK2+/+ et MK2-/-, l’inhibition de COX (indométacine, 1 μM) augmente (p<0.05) la contraction à l’ET-1 des vaisseaux isolés provenant de souris MK2+/+ mais pas des MK2-/-. Ces données suggèrent un rôle de MK2 dans la réponse vasculaire à l’ET-1 et possiblement dans la signalisation post-récepteur de l’ET-1 en général. / Endothelin-1 (ET-1) is a potent vasoconstrictor whose production is deregulated in many inflammatory related diseases in which the cyclooxygenase-1/2 (COX-1/2) is up-regulated. Since it is known that the p38 MAPK pathway regulates ET-1 expression at the mRNA level, we studied the implication of the downstream kinase MK2 in the post-transcriptional regulation of ET-1 and COX. To accomplish this, MK2-deficient mice (MK2-/-) and their wild type littermate controls (MK2+/+) were used. Cardiac function parameters were measured using a Millar catheter under anesthesia and isometric reactivity of the isolated femoral artery was measured subsequently using a wire myograph. Aortic endothelial cell (EC) ET-1, COX-1 and COX-2 expression was quantified by qPCR. In response to ET-1 (100 nM), EC expression of preproET-1 increased in a time-dependant manner (p<0.05): this change in mRNA was greater in MK2-/- mice. Although arterial pressure was similar in MK2+/+ and MK2-/- mice, inhibition of COX (indomethacin, 1 μM) increased (p<0.05) the contraction of isolated vessels to ET-1 from MK2+/+ but not MK2-/- mice. These data suggest a role of MK2 in the vascular response to ET-1 and, possibly, ET-1 post-receptor signalling in general.

As mulheres na fase reprodutiva apresentam menor incidência de doenças cardiovasculares (DCV), em relação aos homens de mesma idade. Porém, essa vantagem desaparece na pós-menopausa, sugerindo que os hormônios sexuais femininos exercem algum efeito cardioprotetor. Um dos mecanismos propostos para explicar essa proteção é o fato dos estrógenos promoverem a produção de importantes fatores vasoativos pelo endotélio vascular, entre eles o óxido nítrico e a prostaglandina I2. Com a diminuição da quantidade de estrógenos circulante, as mulheres na pós-menopausa, estão mais suscetíveis à disfunção endotelial e a doenças cardiovasculares. Estudos têm demonstrado que a terapia de reposição hormonal (TRH) utilizada por mulheres na pós-menopausa combate os sintomas deste período, melhora o quadro de disfunção endotelial e o perfil lipídico e aumenta a síntese de fatores vasoativos, que auxiliam na prevenção da DCV. Entretanto a TRH vem sendo questionada por grandes estudos como o WHI (Writing Group for the Women\'s Health Initiative Investigators) e o HERS (Heart and Estrogen/Progestin Replacement Study), que mostraram um risco aumentado de desenvolvimento de câncer de mama e endometrial em mulheres fazendo uso da TRH. Entre as terapias alternativas para combater os sintomas indesejáveis da menopausa e as implicações mórbidas que acompanham esse período, sem expor as pacientes aos efeitos colaterais da TRH, a literatura aponta os fitoestrógenos, principalmente os extraídos da soja (Glycine max). O objetivo geral deste estudo é avaliar a ação das isoflavonas da soja, que vem sendo utilizadas por mulheres na pós-menopausa, na produção de óxido nítrico, prostaglandina E2 e endotelina-1, por células endoteliais, utilizando um modelo \"in vitro\", células endoteliais da linhagem ECV304. / During their reproductive years, women have a lower incidence of coronary heart disease (CHD) compared to men of similar age. However, this advantage disappears in post-menopause, suggesting that female sex hormones exert some cardio protective effect. One of the mechanisms proposed to explain this protection is the fact that estrogens promote the production of important vasoative factors by vascular endothelium, including nitric oxide and prostaglandin I2. By decreasing circulating estrogen, women in post-menopause are more susceptible of endothelial dysfunction and cardiovascular diseases. Studies have shown that the hormone replacement therapy (HRT) used by post-menopausal women in combating the symptoms of this period, improve endothelial dysfunction and lipid profile and increases the synthesis of vasoative factors, which help in the prevention of CHD. Meanwhile the HRT has been questioned by two large trials, the WHI (Writing Group for the Women\'s Health Initiative Investigators) and HERS (Heart and Estrogen/Progestin Replacement Study), which showed an increased risk of developing breast cancer and endometrial cancer in women using HRT. Among the alternative therapies to combat the symptoms of menopause and undesirable morbid implications that accompany this period, without exposing the patients to the side effects of HRT, the literature suggests the phytoestrogens, especially those from the soybean (Glycine max). The aim of this study is to evaluate the effect of isoflavones from soy, which are used by women in post-menopause, in the production of nitric oxide, prostaglandin E2 and endothelin-1 by endothelial cells, using an \"in vitro\" model: human endothelial cell line ECV304.

Thesis (Ph. D.)--University of Missouri--Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 152-178). Also available on the Internet.