Os mecanismos que regulam a contractilidade das células do músculo liso da artéria umbilical humana são muito importantes para permitir a troca de gases e nutrientes entre o feto e a placenta. Uma vez que a artéria é desprovida de inervação, o controlo do tónus vascular é completamente dependente de alguns iões como o potássio e o cálcio, dos mediadores vasoativos libertados localmente e de substâncias transportadas pelo fluxo sanguíneo, como a histamina e serotonina (5-hidroxiptamina). Vários autores descrevem que o aumento da libertação destes mediadores, assim como a sensibilização da artéria umbilical humana (HUA) aos mesmos, pode levar ao aparecimento da pré-eclampsia. Por outro lado, uma correcta regulação do tónus do músculo liso vascular é fundamental na manutenção de funções biológicas e a desregulação pode resultar em diversas patologias. O mecanismo de contração do músculo liso é iniciado por ativação de um recetor ou de um canal iónico e envolve mecanismos que podem ser dependentes ou independentes de cálcio (“sensibilização ao cálcio”). A via da Rho-cinase (ROCK) está intrinsecamente envolvida no processo de contração do músculo liso e tem sido envolvida em outros processos celulares. Estudos prévios realizados pelo nosso grupo demonstraram que a ROCK está envolvida no processo de regulação da contractilidade da artéria umbilical na presença de cálcio. Assim, este projeto pretende determinar o papel desta cinase, assim como analisar a influência do cálcio extracelular nesta via, usando células do músculo liso (SMC) da HUA. Para além disso, pretende também estudar a possível relação entre a via do cGMP/PKG e a ROCK. Foi utilizada a técnica PCSA (“planar cell surface área”). As SMC foram previamente marcadas com um fluoróforo (fluoresceína) e analisadas com recurso a um microscópio de fluorescência. Inicialmente analisou-se a contractilidade das SMC em meio com diferentes concentrações de cálcio extracelular e na ausência deste. As artérias foram previamente contraídas por 5-HT (1 μM) e por histamina (10 μM). Para testar o efeito da via da ROCK foi utilizado um inibidor da ROCK (Y27236) em presença de diferentes concentrações de cálcio extracelular. O possível envolvimento da PKG na via da ROCK foi analisado usando um dador de óxido nítrico (SNP 40 μM). Os resultados demonstraram que a diferentes concentrações de cálcio (0,1; 0,2; 0,5; 1; 2 e 3 mM), as SMC pré-contraídas por 5-HT apresentaram contrações similares para as diferentes concentrações de cálcio. Pelo contrário, as SMC pré-contraídas pela histamina apresentaram contrações superiores na presença de 0,5 mM e 2 mM de cálcio extracelular. Em meio sem cálcio, a histamina induziu maior efeito contráctil que a 5-HT. Em relação ao papel da ROCK na contractilidade da HUA, verificamos que para ambos os agentes contracteis analisados, a inibição da ROCK não teve influência na contração das SMC. O SNP não alterou o efeito contráctil da 5-HT e da histamina independentemente da concentração de cálcio assim como na ausência deste. Nas células contraídas pela 5-HT a uma concentração de 1 mM de cálcio extracelular, o inibidor da ROCK, modificou significativamente o efeito relaxante do SNP. No referente à histamina verificou-se que independentemente das concentrações de cálcio utilizadas, o Y27 não modificou o efeito da administração conjunta da histamina e SNP. Em suma, os nossos resultados evidenciaram que a contractilidade da HUA é muito sensível a diferentes concentrações de cálcio extracelular, o que indica que este ião regula de uma forma dinâmica a contractilidade das SMC vasculares. Os nossos resultados também permitem concluir que a contractilidade da HUA não é regulada pela via da ROCK e que as alterações na concentração de cGMP não intervêm na inibição desta via.

A artéria umbilical humana (HUA) está envolvida na circulação fetoplacentária. Os mecanismos endócrinos e parácrinos, que regulam o estado contráctil das células musculares lisas, são muito importantes para uma óptima troca de gases e nutrientes entre o feto e a placenta, uma vez que os vasos sanguíneos umbilicais não são enervados. Estudos anteriores demonstraram que 17β-estradiol induz um relaxamento vascular da HUA, dependente da concentração de hormona adicionada, no entanto, o mecanismo vasorelaxante desta hormona ainda permanece por esclarecer. O efeito do 17β-estradiol na contractilidade desta artéria foi analisado. Foi investigado o mecanismo vasorelaxante do estradiol, e sua participação na actividade dos canais iónicos e dos nucleótidos cíclicos (AMPc e GMPc). Estes últimos, são os principais segundos mensageiros ligados à vasodilatação. São sintetizados por ciclases e degradados por diferentes tipos de fosfodiesterases (PDE’s). Usando uma técnica de banho de órgãos, os anéis de artérias umbilicais humanas (HUA) sem endotélio foram contraídos com seretonina (5-HT, 1 μ M), histamina (10 μ M) e cloreto de potássio (KCl, 60 mm). Foi observado que o 17β-estradiol, para a concentração máxima utilizada (100 μ M), induz um efeito vasorelaxante nas AUH, contraídas com 5-HT (34,3 ± 4,9%), histamina (55,9 ± 4,1%) e KCl 60 mM (51,4 ± 6,5%). A utilização de glibenclamida, um inibidor de canais de potássio dependentes de ATP (KATP), a 4-aminopiridina, um inibidor de canais de potássio dependentes de voltagem (Kv) e um inibidor de canais de potássio dependentes de cálcio (KCa), o tetraetilamonio (TEA), reduziu o efeito vasorelaxante do 17β-estradiol em HUA contraídas com histamina. Em artérias contraídas com KCl (60 mM) e 5-HT (1 μ M), apenas a 4-aminopiridina e a TEA, diminuíram o efeito do 17β-estradiol. Foi também observado, o efeito da nifedipina, um inibidor de canais de cálcio dependentes de voltagem tipo L. Foi observado que a sua adição não influenciou o efeito relaxante do 17β-estradiol nas artérias contraídas com 5-HT, histamina e KCl. Foi demonstrado, que a estimulação da guanilciclase, pelo ANP (péptido natriurético atrial), relaxa a AUH em contracções induzidas com a histamina e 5-HT. Isto indica que, o aumento intracelular do nucleótido cíclico, GMPc, leva à vasodilatação da artéria umbilical humana. Investigou-se também, o efeito da inibição de PDE´s nas artérias contraídas com 5-HT (1 μ M) e histamina (10 μ M). Demonstrou-se que o inibidor inespecífico das PDE’s, o IBMX (3-isobutyl-1-methylxanthine, 50 μ M) relaxou as AUH contraídas com histamina (49,9% ± 5,4) e 5-HT (20,7% ± 6,5), o que aumentou o efeito relaxante do ANP, quando as artérias são contraídas com histamina (72,5% ± 3.7). Por fim, analisamos o efeito dos inibidores da guanilciclase, ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, 30 μ M) e da adenilciclase, SQ (9-(Tetrahydro-2-furanyl)-9H-purin-6-amine,100 μM) em artérias contraídas com 5-HT (1 μ M) e histamina (10 μ M). Observamos uma diminuição do relaxamento provocado pelo estradiol quando estes inibidores foram utilizados. Em resumo, os nossos resultados demonstram que, o relaxamento induzido pelo 17β-estradiol é parcialmente mediado pela activação de canais de K+ e pelo bloqueio dos canais de Ca2+. O aumento dos níveis de GMPc induz o relaxamento do músculo liso vascular do cordão umbilical humano. As PDE’s estão envolvidas no relaxamento muscular mediado pelo ANP. O inibidor de guanilciclase reduz os efeitos relaxantes do 17β-estradiol em artérias contraídas com 5-HT (1 μ M) e com histamina (10 μ M).

Nas últimas décadas, vários investigadores têm sugerido uma associação entre os androgénios e a hipertensão. Os efeitos benéficos dos androgénios no sistema vascular estão associados com a sua capacidade para provocar vasorelaxamento vascular. Os efeitos não genómicos dos androgénios nas células vasculares do musculo liso parecem ser devidos à ativação dos canais de potássio ativados pelo Ca2+ de elevada condutância (BKCa) e dos canais de potássio sensíveis à voltagem (KV) e/ou à inibição dos canais de Ca2+ dependentes da voltagem tipo L (L-VOCC). Contudo os efeitos genómicos dos androgénios, nomeadamente na expressão destes canais iónicos, são pouco conhecidos. No entanto em estudos anteriores observou-se que os androgénios podem ser benéficos a nível cardiovascular pois têm efeitos vasodilatadores, e aumentam a expressão dos canais BKCa e dos Kv. A hipertensão é um dos problema mais comums na gravidez que complica 5% a 10% das situações de gravidez. Apesar da morbilidade significativa associada aos bebés nascidos de grávidas com hipertensão, a patogénese permanece por esclarecer, o que limita a capacidade de preveni-la e trata-la. O objetivo deste trabalho foi analisar os efeitos genómicos dos androgénios na expressão de diferentes proteínas envolvidas na regulação da contrátilidade vascular, nomeadamente da guanilato ciclase solúvel (sGC), do recetor do péptido natriurético-A (NPRA) e da proteína cinase G (PKG). Estas proteínas parecem estar envolvidas no mecanismo vasodilatador provocado pelos androgénios. Este trabalho também teve como objetivo a comparação entre os níveis de expressão destas proteínas em artérias umbilicais humanas (HUA) provenientes de grávidas normotensas e de grávidas hipertensas. Para atingir estes objetivos foi utilisada a técnica de PCR em tempo real em células do músculo liso de HUA, as quais foram pré-incubadas durante 24 horas com DHT (1-1000nM). Em células musculares de HUA provenientes de grávidas normotensas, os androgénios provocaram uma diminuição da expressão da sGC e da PKG, e um aumento na expressão do NPRA. No entanto, em células musculares de HUA provenientes de grávidas hipertensas os androgénios provocam uma diminuição da expressão da sGC, da NPRA e um aumento da expressão da PKG. Em suma, podemos concluir que o DHT modula a expressão das proteínas analisadas, as quais estão envolvidas no mecanismo vasodilatador dos androgénios.

Every day, an extensive and varied range of emerging contaminants encounter humans. Exposure to these endocrine-disrupting chemicals (EDCs) is not without risks and has even been associated with adverse effects on multiple human systems, including the cardiovascular system. Due to the fundamental role of thyroid hormones (TH) in vascular homeostasis, EDCs capable of disturbing thyroid homeostasis (thyroid disruptive chemicals, TDCs) may increase the risk of cardiovascular disease (CVD). However, the mechanisms underlying thyroid disruption associated with the progression or development of CVD are not fully understood. Endocrine disruption is one of the biggest concerns and, therefore, one of the most extensive research forces. Endocrine disruption comprises a diverse set of target organs, processes, and modes of action (MoA), with multiple interactions and complex actions. Periods of development, such as pregnancy, are susceptible to endocrine disruption and constitute a priority area of research. Pregnant women often use various personal care products containing UV filters. The UV-B filters are designed to protect humans against the biological effects of UV radiation. However, their use has been questioned, and some concerns of toxicity to human health have emerged, demonstrating an EDC role for some UV filters. Octylmethoxycinnamate (OMC) is one of the most used UV-B filters worldwide. However, the OMC is also an EDC that affects human health and the environment, and its use remains under intense controversy. The scientific community has given special importance to the environmental and severe effects on coral reefs and aquatic species, which led to OMC being withdrawn from the market in different countries since 2018. On the contrary, the endocrine-disrupting effects in humans have been neglected despite in vitro studies having proven effects at the estrogenic level and non-consensual effects concerning (anti)thyroid and (anti)androgenic activities. Based on the above, it is worrying that the effects of a UV filter widely used worldwide are practically unknown on human health. Within the scope of my MSc dissertation, we demonstrated that OMC acts as a rapid vasodilator of the human umbilical artery (HUA). Although this vasorelaxation has a short-term beneficial effect on the vascular system, also observed with other EDCs, in the long term, all EDCs studied impaired the main vasorelaxation mechanisms of HUA through different MoA. In the case of OMC, only one study evaluated its short-term effects on human vasculature, and the effects of its long-term exposure on human health were not known until this research. Therefore, the main objective of this doctoral thesis was to understand whether exposure to the OMC UV filter impairs human vascular function in the presence of thyroid disorders. We hypothesize that exposure to OMC has adverse effects on the human vasculature, altering the expression of different receptors involved in thyroid functions. To achieve our objective and answer our research hypothesis, various in silico (molecular docking), ex vivo, in vitro (HUA and human umbilical artery smooth muscle cells, HUASMC), and in vivo (zebrafish) approaches were outlined. The first research work analysed the effects of long-term exposure to OMC on HUA vascular homeostasis. Potential changes in the vascular responses of proteins and channels involved in contractile processes were the focus of the research. The effects of 24- hour exposure to OMC (1, 10, and 50 μmol/L) were evaluated on HUA contractile responses to serotonin (5-HT) and potassium chloride (KCl). The data showed that exposure to OMC altered HUA vascular homeostasis; therefore, its MoA was explored in more detail by studying the activity of cyclic guanosine 3’,5’–monophosphate (cGMP) and Ca2+ channels (two pathways involved in its relaxation and contraction, respectively). Prolonged exposure to OMC impaired the main vasorelaxant mechanism of HUA. Interference in the nitric oxide (NO)/soluble guanyl cyclase (sGC)/cGMP/protein kinase G (PKG) signaling pathway and modulation of L-Type voltage-operated Ca2+ channels, BKCa1.1 potassium channels (α subunit), and PKG were the MoA implicated in the decrease in the contractile response. This work demonstrated that OMC could compromise vascular homeostasis in pregnant women and may have a role in the induction of hypertensive diseases of pregnancy. The HUA is regulated mainly by local mediators (5-HT and histamine, His). Membrane receptors, such as G protein-coupled receptors, GPCR induce the effects of these mediators which, when altered, compromises maternal-foetal health. Elevated levels of 5-HT and His increased HUA reactivity/sensitivity to these vasoactive agents, increasing vascular resistance and inducing preeclampsia (PE) and gestational hypertension. On the other hand, it has been demonstrated that EDCs can activate membrane receptors and alter signal transduction. Based on the above and considering the results obtained in the first study, our second research work deepened knowledge about the effects of prolonged exposure to OMC on vascular homeostasis, evaluating the modulation of receptors involved in the contractile processes of HUA. In this work, the research focused on the activity and expression of different 5-HT and His receptors. Thus, the effects of 24-hour exposure to OMC (1, 10 and 50 μmol/L) were evaluated on the contractile responses of HUA to 5-HT and His, using different specific agonists and antagonists, namely 5-HT2A receptor agonist (AMHT), 5-HT7 receptor agonist (AS19), 5- HT1B/1D receptor agonist (L69), H1 receptor agonist (BHI), H2 receptor agonist (dimaprit) and H2 receptor antagonist (cimetidine). Our results demonstrated that exposure to OMC increased HUA reactivity to the vasoactive agents under study. Consequently, and in line with previous research, our results denote a potential role for OMC in the development of hypertensive diseases of pregnancy, such as PE or gestational hypertension. In the third research work, the effects of short- and long-term exposure to OMC were evaluated on the vasculature of pregnant women with hypothyroidism. Although it has been suggested that OMC is a TDC due to its action on thyroid hormone receptor (TR), its disruptive effects on thyroid pathologies during pregnancy have never been evaluated. Therefore, in this study, we assessed the disruptive vascular effects of OMC in hypothyroidism conditions. Computational simulations using molecular docking allowed the correlation of vascular changes with the action of OMC on TRα. Our results indicated that OMC alters the contractility patterns of HUA contracted with 5-HT, His, and KCl, possibly due to interference with 5-HT and His receptors and/or involvement of Ca2+ channels (as shown in two previous investigations, in the absence of thyroid pathologies). Molecular docking analysis confirmed OMC competition with the endogenous hormone T3 for binding to the active centre of TRα, supporting the observed vascular changes. Taken together, our data demonstrate that exposure to OMC alters the vascular reactivity of pregnant women with thyroid pathologies and, thus, may be related to an increased risk and development of cardiovascular diseases. In the fourth research work, developing zebrafish embryos were used as a model to study the effects of OMC exposure in conditions of thyroid pathologies. This work aimed to unravel whether and how the response to OMC exposure is altered by developmental hypothyroidism and hyperthyroidism simulated conditions in zebrafish developing embryos and impair their normal development. For this purpose, developmental hypothyroidism and hyperthyroidism were induced through exogenous exposure to PTU (propylthiouracil, an anti-thyroid drug) or T3 (triiodothyronine endogenous hormone), respectively. Then, embryos were exposed during 120h to OMC isolated and in binary mixture with PTU or T3. In hypo- or hyperthyroidism developmental conditions, exposure to OMC impaired the embryonic development of zebrafish through the induction of several malformations. Pericardial and yolk sac oedema, yolk sac delayed absorption, noninflation of the swim bladder, notochord curvature, and lack of pigmentation were the most prevalent malformations. Furthermore, exposure to OMC under these conditions impairs the behaviour of larvae. Altered transcription of genes related with the HPT axis found proves the TDC action of the OMC. Our findings highlight a modified OMC response in the presence of thyroid pathologies, with harmful effects in development period more sensitive to endocrine disruption, which is in line with research work III. Lastly, the fifth research work was based on the study of the molecular interactions of the OMC in the HPT axis and their implications for humans and zebrafish. This in silico research aimed to reveal the different modes of interaction of the OMC at different levels of the HPT axis, comparing it to the PTU and T3. Our results demonstrated an action of OMC at different levels on the HPT axis, with different actions depending on the target. Molecular docking analysis revealed favourable binding to the corticotrophin-releasing hormone (CRH) receptor and the TH transporter protein, transthyretin (TTR). Furthermore, competition with T3 (inverse agonist activity) was observed for TRα and TRβ. Overall, the action of OMC appears to lead to a decrease in TH, which may promote hypothyroidism. This investigation proves that the OMC acts as a TDC and offers new insights about its disruptive action on the HPT axis, capable of supporting previous investigations. In summary, this doctoral thesis analysed the effects of prolonged exposure to OMC on human vasculature for the first time. Our mechanistic and integrative in silico, ex vivo, in vitro and in vivo approaches demonstrate that OMC impairs vascular homeostasis in pregnant women with and without thyroid pathologies, acting through different molecular initiating events (MIEs) and key events (Kes). Consequently, exposure to OMC can induce the development of cardiovascular diseases. Complementation with in vivo studies made it possible to prove the action of OMC on the HPT axis since the response to OMC was altered in the presence of both thyroid pathologies. In silico studies compared its thyroid modulatory activity to that of the endogenous hormone T3 and the antithyroid drug PTU, which revealed interference at different levels in the HPT axis. Considering the agonist and antagonist actions as an endocrine disruptor, we conclude that prolonged exposure to OMC triggers pathophysiological mechanisms capable of inducing vascular changes with implications for human thyroid health.

Phthalates are chemical compounds used as plasticizers to increase flexibility and elasticity of rigid polymers and as non-plasticizers as solvents and additives in cosmetics and personal care products. These compounds have low water solubility and since they are not covalently bound to the polymer they are easily released into the environment and absorbed by the human body. Afterwards, phthalates are rapidly metabolized into their respective monoesters being already detected in different biological samples, including blood, urine, saliva, amniotic fluid, umbilical cord blood and breast milk. In addition, phthalates can disrupt the endocrine system by binding to molecular targets and interfering with hormonal homeostasis, thus being classified as endocrine-disrupting compounds (EDCs). Due to these properties and their adverse effects, phthalates were classified as priority environmental pollutants by the United States Environmental Protection Agency (US EPA). Alongside this increase in exposure to phthalates, the incidence of cardiovascular diseases (CVD) has also increased over the years, with the occurrence of hypertensive disorders in pregnancy (HDP) being one of the main causes of maternal and foetal morbidity and mortality. There are several risk factors that influence the development of HDP, including exposure to EDCs, but the mechanisms involved are not yet known. Several studies have also suggested an association with phthalates, in rats they seem to promote changes in the vascular function, to affect the expression of proteins involved in cardiac function, to contribute to increased blood pressure, changes in lipid metabolism, and atherosclerosis. Thus, the aim of this thesis was to investigate how phthalates’ exposure affects the cardiovascular health, focusing on HDP. For that, studies were carried out on rat aorta and the human umbilical artery to evaluate the effects of di(2-ethylhexyl) phthalate (DEHP) and diethyl phthalate (DEP) in the vascular function. In the first study, rat aorta devoid of endothelium was contracted with noradrenaline and potassium chloride (KCl) and then subjected to different concentrations of DEHP (0.001-100 μM) to assess the vascular reactivity. Besides, since Ca2+ levels are the main determinant of contraction and relaxation, DEHP effects on Ca2+ currents were also analysed using the A7r5 cells. The data obtained showed that DEHP caused a concentration-dependent vasorelaxation after contraction with KCl, and, at the highest concentrations, it inhibited both the basal and the BAY K8644-stimulated calcium currents. These results suggest that DEHP induces vasorelaxation of the rat aorta by inhibiting the L-type Ca2+ channels (LTCC). Then, the genomic and non-genomic effects of DEP on the rat aorta were analysed. Using the organ bath technique, DEP (0.001-1000 μM) was analysed after contraction of the arteries with noradrenaline and KCl. Similarly, to understand the possible mechanisms involved, the effects of DEP were analysed on the relaxing effect of nifedipine (NIF - specific calcium channel blocker) and sodium nitroprusside (SNP - soluble guanylate cyclase activator). Besides, through electrophysiology studies the non-genomic (occurring within a few minutes) and genomic (occurring after 24h of exposure) effects of DEP on the Ca2+ currents of the A7r5 cells were investigated. These showed that both the rapid and 24h effects of DEP exposure led to a decrease in LTCC currents, being in agreement with the vasorelaxation obtained through the organ bath experiments. For the first time, the vascular electrophysiological properties of an EDC were analysed after long-term exposure, concluding that DEP promotes an inhibition of the calcium current in the rat aorta, which may be responsible for electrical disturbances such as arrhythmias. To evaluate the effect of phthalates on maternal health, the last experimental work of this thesis analysed the contribution of DEP (0.001-1000 μM) in the development of gestational hypertension. Therefore, human umbilical arteries (HUA) were collected from normotensive and hypertensive pregnant women. To assess the non-genomic vascular effects, the HUA were pre-contracted with serotonin, histamine and KCl and then subjected to DEP, resulting in a vasorelaxation by interfering with Ca2+ channels and serotonin and histamine receptors. On the other hand, to assess the genomic effects, the arteries were incubated with DEP for 24h, and then the effects of NIF and SNP were analysed. The results showed that DEP seemed to act through the NO/sGC/cGMP/PKG signalling pathway, and to interfere with LTCC. In addition, primary culture of HUA smooth muscle cells was also performed for cell viability essays, showing that DEP has no toxic effect on these cells. Overall, this experimental work showed that DEP affects the HUA vascular resistance through disturbances in hormone and calcium homeostasis, suggesting that the development of hypertension in pregnancy may be a consequence of exposure to phthalates. In general, the results obtained show that phthalates modify the vascular homeostasis in both animals and humans, promoting vasorelaxation mainly through the inhibition of Ca2+ channels. This is the first time that an experimental study has been able to establish the link between exposure to DEP and gestational hypertension. We are beginning to unravel the mechanistic pathways involved in the vascular effects of phthalates that explain the pathological functional alterations of hypertension in pregnancy. However, more experimental studies are needed to understand how different classes and mixtures of phthalates affect the cardiovascular health during pregnancy and in future generations.

Diversos estudos indicam que o risco de desenvolvimento de Doença Arterial Coronária e Hipertensão é superior nos homens do que em mulheres pré-menopausa. Postula-se que seja resultado de efeitos desfavoráveis da hormona testosterona. No entanto esta mostrou ter efeitos não genómicos vasodilatadores, que podem estar envolvidos num efeito protectivo, mas este assunto ainda não está clarificada. Foi estudado a acção da testosterona e do colesterol nos canais de cálcio tipo L e nos canais de potássio nas células A7r5. O efeito da testosterona nos canais activados por nucleótidos cíclicos foi também estudado nas células musculares lisas da artéria umbilical humana. Para tal foi utilizado um sistema de patch clamp. A testosterona e o colesterol inibiram as correntes de cálcio tipo L, tanto basais como estimuladas por Bay K8644, de forma concentração-dependente. As correntes de potássio não sofreram alterações significativas. A testosterona foi também capaz de activar as correntes de canais de CNG. Tendo em conta os resultados obtidos, podemos afirmar que a testosterona e colesterol induzem relaxação nas células de músculo liso de aorta de rato. Estes dados sugerem que estes esteróides partilham um mecanismo de acção comum nestas células, estando nele envolvido a inactivação dos canais de cálcio, LTCCs. Nas células do músculo liso vascular da artéria umbilical humana verificou-se um aumento do cGMP, indicando que o mecanismo envolvido na relaxação pela testosterona envolve a via do cGMP.

O bisfenol A (BPA) é um composto orgânico largamente utilizado na indústria de plásticos, tintas / vernizes, materiais de conexão e materiais de enchimento. É também utilizado como retardador de chamas, fluidos para travões e papéis térmicos. O BPA é maioritariamente utilizado na produção de plásticos (~ 3,8 milhões de toneladas por ano), incluindo embalagens de alimentos, brinquedos, monómeros odontológicos e equipamentos médicos. A exposição ao BPA varia drasticamente com o estilo de vida de cada indivíduo, sendo que a gama de valores até agora registados, provenientes de amostras de sangue recolhidas a partir de indivíduos adultos, varia de 0,001 M a 3 M. [...]