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The authors design an animal model of neonatal sepsis to analyze the treatment of neonatal septic shock with Methylene Blue (MB) in a swine model.The study design included twenty male newborn pigs divided into four groups: 1) The control group; 2) The sepsis group (induced with lipopolysaccharide); 3) The MB group, and 4) The MB-treated sepsis group. Septic shock was defined as Blood Pressure (BP) dropping 20% below the baseline value. Continuous Blood Pressure (BP), Nitric Oxide (NO) levels, cyclic Guanosine Monophosphate (cGMP), malondialdehyde acid, base excess, lactate, arterial blood gases, hematocrit, and echocardiography were analyzed.The BP of the sepsis group treated with MB showed a slight improvement in the first hour after treatment; however, a significant difference was not observed compared to the untreated sepsis group. Besides hemodynamic stability, the current study did not show symptomatic pulmonary hypertension, suggesting that MB was safe in neonates and children. An improvement in Base Excel (BE) levels after MB administration in septic animals may indicate a possible improvement in microcirculation.The MB improved biomarkers related to septic shock prognosis, although an improvement in the blood levels could not be detected. MB might be a beneficial drug for hemodynamic instability in infants.

Soluble guanylate cyclase (sGC) is the primary enzyme responsible for catalyzing the conversion of guanosine-5′ triphosphate (GTP) to guanosine 3′5′-cyclic monophosphate (cGMP), and it has been described for nearly 40 years after its identification in mammalian cells. Nitric oxide (NO) was described in the late 1970s as responsible for its activation and, therefore, for the formation of cGMP. Ten years later, when the endothelium-derived relaxing factor (EDRF) was discovered and identified as NO, mammalian cells were shown capable of synthesizing this inorganic compound, identifying it then as an endogenous sGC activator. The result was the characterization of the NO-sGC-cGMP transduction system. The stimulation of sGC by NO causes relaxation, increasing the cGMP production and activating cGMP-dependent protein kinase (PKG).

Acid-base disorders are common in medical practice, especially in patients with circulatory shock. These disorders can range from a simple acidosis or alkalosis to a complex mixed disorder that can lead to death. In general, these changes are manifestations or complications of pre-existing pathologies, such as central nervous system (CNS) impairment, pulmonary failure, endotoxic shock, cardiac arrest, chronic renal failure, adrenal hyperactivity, diabetes mellitus, liver problems, sepsis, or even medical maneuvers such as cardiopulmonary bypass and mechanical ventilation. In situations of acidosis or alkalosis, changes in cell permeability and cellular enzymatic function are noted, which can lead to the dysfunction of several organs and systems. These systemic changes promoted by pH variations are quite diverse: increased pulmonary vascular resistance; reduction of systemic vascular resistance; alteration of the electrical activity of the myocardium and the central nervous system; changes in myocardial contractility; and modification of the response to specific chemical agents, endogenous, and exogenous, such as hormones and vasoactive drugs.

Although methylene blue (MB) has been used for more than 20 years in the treatment of vasoplegic syndrome (VS), few quality clinical studies can allow the procedure to become a protocol. The pathophysiology of vasoplegia after cardiopulmonary bypass is multifactorial, with no final consensus on its real mechanism. For didactic purposes, emphasis will be given to three aspects, which are the most mentioned in clinical and laboratory studies on the subject: (a) the systemic inflammatory reaction; (b) the effects of protamine; and (c) a new mechanism recently related to the impairment of vasopressin receptors. There is strong evidence that MB, a guanylate cyclase inhibitor, is an excellent therapeutic option for the treatment of VS in cardiac surgery. Our clinical and laboratory experience, accumulated over a period of 20 years, established some classic concepts about the use of MB in this condition.

Nitric oxide (NO) is a central mediator of many physiological and pathophysiological events. After a thermal injury, an increase in NO was observed in the plasma and urinary levels, but the real importance of this fact is unknown. The guanylate cyclase inhibition by methylene blue (MB) has been proven, in basic and clinical studies, as an adjuvant treatment option in cases of catecholamine-resistant vasoplegia. Its use is safe, generally lifesaving, and the pharmacological inhibition of NO interferes not only in the reversal of vasoplegia but also in vascular permeability, often caused by the systemic inflammatory response associated with burns. Increasing experimental and clinical studies suggest MB as a viable, safe, and useful coadjuvant therapeutic tool for fluid resuscitation.

The idea that inhaled nitric oxide (NO) could cause selective pulmonary vasodilation motivated studies in animals where several mechanisms produced pulmonary hypertension. These studies demonstrated that concentrations of 5–80 ppm produced rapid and reversible pulmonary vasodilation, without systemic effects or adverse reactions. In the lung, as in any other part of the body, the NO formed from L-arginine in a reaction catalyzed by nitric oxide synthase (NOS) induces vasodilation through a guanosine 3′5′-cyclic monophosphate (cGMP)-dependent pathway. Since NO exists as a gas, it can be administered by inhalation to the alveoli and blood vessels close to these alveoli. As it undergoes rapid inactivation by hemoglobin, inhaled NO can perform selective pulmonary vasodilation when there is pulmonary vasoconstriction, without causing systemic vasodilation.

Since the mid-1970s of the last century, the presence of H1 and H2 receptors in the pulmonary and systemic circulation has been described, illustrating the importance of histamine in anaphylactic shock (ASh) mediation, since when released and transported by the bloodstream, it can produce an effect on the entire cardiovascular system, in addition to other tissues where histaminergic receptors can also be found. One of the hypotheses that could explain the important vasodilatory effect of histamine in ASh is that histamine binds to H1 receptors in the vascular endothelium, activating the nitric oxide (NO) production, one of the relaxing factors derived from the endothelium, which diffuses to vascular smooth muscle and activates the guanosine 3′5′-cyclic monophosphate (cGMP) production, resulting in vasodilation. Histamine can also bind to H2 receptors present in vascular smooth muscle, activating the adenosine 3′5′-cyclic monophosphate (cAMP) production pathway that also results in vasodilation. Thus, the vasodilation resulting from the activation of the cGMP and cAMP pathways synergistically contribute to the development and maintenance of the characteristic ASh hypotension. Therefore, treatment of Ash with MB is an option as rescue therapy.

Infectious endocarditis is a life-threatening condition that occasionally requires emergency valve replacement. Patients with an ongoing systemic inflammatory response because of infective endocarditis (IE) and those who need cardiopulmonary bypass (CPB) for emergency valve replacement may demonstrate resistant hypotension related to vasoplegia. It presents a spectrum of clinical presentation and is associated with a systemic inflammatory response and the release of endothelial nitric oxide (NO). Hemodynamically it is characterized by arterial vasodilation, high cardiac output despite myocardial depression, and decreased sensitivity of the heart and peripheral vessels to sympathomimetic agents. These observations led us to propose a protocol with the use of MB in cases of emergency surgery in patients with vasoplegic syndrome: (1) 3 mg.Kg−1 bolus infusion right after anesthetic induction (perhaps even earlier); (2) infusion of 1 mg.Kg−1 (intravenous (IV) or in the oxygenator) if blood pressure maintenance is not possible due to high perfusion flow and high doses of norepinephrine, and (3) repeat the infusion in bolus (or continuous if the patient is stable) after CPB discontinuity.

Since the 1990s, nitric oxide (NO) has been associated with vasoplegia of septic shock resistant to high doses of catecholamines. After exposure to bacterial endotoxin or specific cytokines, the inducible nitric oxide synthase (iNOS) expression occurs in a wide variety of tissues. This enzyme produces large NO amounts over long periods, closely related to the pathophysiological changes in sepsis. NO synthesis inhibitors can reverse hypotension caused by endotoxin and cytokine, and these agents could, in theory, constitute a modern therapeutic approach to severe septic shock. Preliminary studies in humans suggest that NOS inhibition improves blood pressure and stabilizes hemodynamics, but mortality rates remain undetermined. It can be said that the use of synthesis inhibitors was associated with increased mortality compared to the control group in humans, causing multicenter studies to be interrupted. The participation of the overproduction of NO by the iNOS expression is evident, leading to a vasoplegia state that is irresponsible to high doses of catecholamines. Since guanylate cyclase is the endothelium-dependent relaxation enzyme, MB is a potent inhibitor of this enzyme and an essential option for the vasoplegia in sepsis treatment.

Before presenting the circulatory shock as a vasoplegic endothelium dysfunction, the classical conceptual and practical approach is, at least, a good editorial choice. The focus of the present abstract begins with the best definition of circulatory shock. Perhaps the best approach to defining the cardiocirculatory shock is that of Robert Hardaway, who begins his discussion by stating, “What shock is not”: (1) low blood pressure; (2) acidosis; (3) low cardiac output; (4) adrenal gland failure, and (5) hypovolemia. This approach is interesting because it demonstrates the entire evolution of the circulatory shock concept as the pathophysiological concepts have changed. So, in search of a universal definition, it was concluded that the best definition of the shock state would be “inadequate capillary perfusion” or, simply, “bad tissue perfusion.” Shock treatment should be aggressive and started early. The fundamental therapy objective is to treat the cause, correct the hemodynamic change, and, at the same time, neutralize abnormalities resulting from poor tissue perfusion. Based on these concepts, the pivotal role of vascular endothelium is made clear.

This chapter was based on the association of the concepts since they are always present when discussing vasoplegic endothelial dysfunction or vasoplegic syndrome. The pathophysiological link is the situation that involves distributive circulatory shock, a hyperdynamic state with low systemic vascular resistance, and arterial hypotension resistant to the effect of vasopressor amines. Many factors associated with the cardiocirculatory shock (surgical trauma, ischemia-reperfusion of organs, changes in body temperature, and release of endotoxins) have been well documented as inducing a complex inflammatory response (SIRS). This inflammatory cascade can contribute to the development of postoperative complications, including, but not limited to, respiratory failure, renal dysfunction, hemorrhagic disorders, neurological dysfunction, and changes in cardiac and liver function, vasoplegic endothelial dysfunction, and, ultimately, multiple organ failure.

Shock treatment in neonatal patients remains a challenge, with difficulties ranging from diagnosis to drug use. The drugs currently available for the treatment of shock are overly aggressive, and patients in shock have worse results showing a higher incidence of serious sequelae, for example, intraventricular cerebral hemorrhage. The main cause of distributive shock in children, especially neonatal patients, is septic shock. Mortality in sepsis is still high worldwide, and neonates and children with distributive shock are especially susceptible to the undesirable side effects of high-dose catecholamine infusions. However, they can significantly benefit from methylene blue (MB) infusion before catecholamine infusions. Unfortunately, there is a widely publicized concept that MB cannot be used in children and neonates because it causes pulmonary hypertension. There is evidence that MB can be a useful medication in neonatal and pediatric hemodynamic management, as it has the potential to minimize the use of traditional vasoactive amines, known to cause a deleterious effect in these patients. Therefore, MB, little studied in pediatrics, can prove to be a beneficial medicine in pediatrics and further studies should be performed.

After the onset of cardiac arrest, global ischemia activates the glia and the complement system with the release of cytokines by neurons. The pro-inflammatory cascade is initiated by the expression of adhesion molecules, polymorphonuclear leukocyte chemotaxis, and the reactive oxygen species production. As a result, there is an increase in vascular permeability, blood clotting activation, platelet activation, and vasoconstrictors release, contributing to the regional flow reduction. Cerebral edema increased blood-brain barrier (BBB) permeability and neurological damage are seen early in ischemia-induced by cardiac arrest. The positive nitric oxide synthase (NOS) regulation is associated with an increase in nitric oxide (NO) production that induces the BBB breakdown. It has been suggested that pretreatment with pharmacological agents can reduce excess NO or oxidative stress, decreasing the interruption of BBB permeability caused by ischemia/reperfusion injury. Methylene blue (MB), a nontoxic dye and scavenger cleaner, recently proved to be a potential aid in the resuscitation of cardiac arrest, attenuating oxidative, inflammatory, myocardial, and neurological lesions.

Cardiogenic shock was classically considered as a left ventricle mechanical failure until the beginning of the century (2000–2003). By this time systemic inflammatory response (SIRS), complement activation, inflammatory cytokines release, inducible nitric oxide synthase (iNOS) expression, and vasodilation would not solely have a crucial position in the shock genesis but also on its evolution. Nowadays, cardiogenic shock, a devastating final result of acute myocardial infarction, is related to extraordinarily excessive mortality. Treatment techniques ought to center attention on rapid reperfusion and hemodynamic support. New pathophysiological interpretations and treatments based totally on vasoplegia triggered through increased iNOS expression have been suggested. The unfavorable evidence for the iNOS inhibition in human cardiogenic shock led to an exceptional suggestion, based on smooth muscle relaxation by guanosine 3′5′-cyclic monophosphate (cGMP), without interfering with NO synthesis and without producing tissue necrosis, associated with the use of NOS inhibitors. Thus, MB for all that has been written in this book could be a therapeutic option, not yet tested, for vasoplegia related to cardiogenic shock.

The endothelium of arteries and veins has long been studied by doctors and researchers who deal with cardiovascular diseases. However, a global view of endothelial function was not possible until the past two decades that witnessed the discovery of prostacyclin production, the subsequent discovery of endothelium-derived nitric oxide (NO), and other vasoactive factors. There are three known endothelium-dependent vasodilation mechanisms: (1) dependent on the cGMP system (NO – nitric oxide); (2) dependent on the adenosine 3′5′-cyclic monophosphate (cAMP) system (PGI2 – prostacyclin); and (3) hyperpolarization (EDHF – hyperpolarizing factor of the endothelium still unknown or nonexistent). These mechanisms are synergistic with each other, with NO being the most important factor, because in addition to being an endogenous vasodilator, it is also an antiplatelet factor. These basic concepts are fundamental to understand the vasoplegic endothelium dysfunction.

Prehospital hypotensive resuscitation with volume resuscitation with reagents that inhibit the free oxygen radical formation, such as MB, can improve resuscitation and survival to treat hypovolemic states. Also, a study in dogs was conducted to assess prehospital resuscitation after refractory hemorrhagic shock with a combination of MB and lactated Ringer’s limited volume solution. Since the early 1990s, studies have investigated nitric oxide (NO) and the induction of calcium-independent nitric oxide synthase (NOS) in the development of vascular hyporeactivity to norepinephrine (NE) and vascular decompensation associated with hemorrhagic shock in experimental animals. Vascular decompensation after prolonged periods of hemorrhagic shock was characterized by an inability of humans and animals to maintain blood pressure, despite blood reinfusion. This progressive decline in blood pressure is mediated by the advanced NO formation by iNOS because it was prevented by L-NMMA or by dexamethasone.

The present review was carried out to describe publications on the use of methylene blue (MB) in pediatrics and neonatology, discussing dose, infusion rate, action characteristics, and possible benefits for a pediatric patient group. The research was performed on the data sources PubMed, BioMed Central, and Embase (updated on Aug 31, 2020) by two independent investigators. The selected articles included human studies that evaluated MB use in pediatric or neonatal patients with vasoplegia due to any cause, regardless of the applied methodology. The MB use and 0 to 18-years-old patients with vasodilatory shock were the adopted criteria. Exclusion criteria were the use of MB in patients without vasoplegia and patients ≥ 18-years-old. The primary endpoint was the increase in mean arterial pressure (MAP). Side effects and dose were also evaluated. Eleven studies were found, of which 10 were case reports, and 1 was a randomized clinical study. Only two of these studies were with neonatal patients (less than 28 days-old), reporting a small number of cases (1 and 6). All studies described the positive action of MB on MAP, allowing the decrease of vasoactive amines in several of them. No severe side effects or death related to the use of the medication were reported. The maximum dose used was 2 mg/kg, but there was no consensus on the infusion rate and drug administration timing. Finally, no theoretical or experimental basis sustains the decision to avoid MB in children claiming it can cause pulmonary hypertension. The same goes for the concern of a possible deleterious effect on inflammatory distress syndrome.

The nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway has a significative influence in hemodynamic changes that occur in transplants. Classically, the ischemia-reperfusion syndrome (IRS) is characterized by hypotension and low vascular resistance, when cGMP and nitric oxide (NO) are increased, contributing to oxidative stress, within an inflammatory context. These mechanisms occur in several types of transplants, such as liver, heart, lungs, kidney, which are a therapeutic choice in several clinical conditions when conventional treatments failed. It is well known the significant relation between graft dysfunction or rejection and ischemia-reperfusion injury that is linked to inflammatory response and NO/cGMP pathway activation. This review aims to study the NO/cGMP pathway in solid organ transplants. Finally, we inquire whether physicians do not underestimate the NO/cGMP pathway.

Anaphylactic shock can be defined as an acute syndrome, and it is the most severe clinical manifestation of allergic diseases. Anaphylactoid reactions are similar to anaphylactic events but differ in the pathophysiological mechanism. Nitric oxide (NO) inhibitors during anaphylaxis suggest that NO might decrease the signs and symptoms of anaphylaxis but exacerbate associated vasodilation. Therefore, blocking the effects of NO on vascular smooth muscle by inhibiting the guanylate cyclase (GC) would be a reasonable strategy. This study aimed to investigate the effects of NO/cGMP pathway inhibitors methylene blue (MB), Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), and indigo carmine (IC) in shock induced by compound 48/80 (C48/80) in rats. The effect was assessed by invasive blood pressure measurement. Shock was initiated by C48/80 intravenous bolus injection 5 min before (prophylactic) or after (treatment) the administration of the inhibitors MB (3 mg/kg), L-NAME (1 mg/kg), and IC (3 mg/kg). Of the groups that received drugs as prophylaxis for shock, only the IC group did not present the final systolic blood pressure (SBP) better than the C48/80 group. Regarding shock treatment with the drugs tested, all groups had the final SBP similar to the C48/80group. Altogether, our results suggested that inhibition of GC and NO synthase in NO production pathway was not sufficient to revert hypotension or significantly improve survival.

Introdução: Os distúrbios ácido-base são comuns na prática médica e podem variar desde uma acidose ou alcalose simples até um distúrbio misto complexo e potencialmente fatal. Em situação de acidose ou alcalose, a permeabilidade iônica e as funções enzimáticas celulares se alteram, acarretando disfunção de diversos órgãos e sistemas. A acidose metabólica (MA), uma condição clínica comum, é causada por uma diminuição no pH do sangue e na concentração de bicarbonato. Pode ocorrer agudamente, com duração de algumas horas a um dia, ou como uma condição crônica, quando o pH normal não pode ser totalmente restaurado. Acidose, como um tipo dominante de distúrbio ácido-base, atualmente, é considerada um fator causador de disfunções cardiovasculares. Poucas pesquisas sobre o efeito da acidose metabólica crônica na função cardíaca, in vivo, estão disponíveis. Assim, é de grande interesse estudar a contratilidade cardíaca in vivo e as mudanças elétricas em resposta a acidose metabólica, além da reatividade vascular em artérias de animais acidóticos. Objetivos: O objetivo do presente estudo foi demonstrar os efeitos da acidose metabólica crônica (AMC) induzida pela administração de cloreto de amônio sobre a função cardiovascular e respiratória, assim como os possíveis mecanismos envolvidos. Metodologia: A AMC foi induzida em ratos Wistar pela substituição de água por uma solução do cloreto de amônio 0,50M ad libitum acrescido de 0,02M por gavagem, durante dez dias. Após dez dias os animais foram agrupados para as demais análises. Foi avaliada a reatividade vascular, frente a diversas drogas vasoativas (Acetilcolina, Fenilefrina, Angiotensina II, Endotelina-1 e ionóforo de cálcio - A23137) utilizando a metodologia de banho de órgão isolado. Algumas curvas dose-resposta foram realizadas na presença de L-NAME. Também foi avaliada a função cardíaca, através do ecocardiograma para pequenos animais, analisando os seguintes parâmetros: débito cardíaco, frequência cardíaca, volume sistólico e encurtamento sistólico e diastólico. A função respiratória foi analisada porResumo pletismografia de corpo inteiro e os parâmetros analisados foram ventilação, volume corrente e frequência respiratória. Além das análises principais citadas acima, foram realizadas também, dosagem de óxido nítrico, análise histológica de rins e dosagens de parâmetros associados a função renal (ureia e creatinina). Resultados: A acidose metabólica crônica (1) potencializou o relaxamento induzido pelo ionóforo de cálcio de maneira dependente do óxido nítrico e não foram observadas alterações para os demais agonistas testados; (2) reduziu o débito cardíaco e volume sistólico, sem alteração na frequência cardíaca; (3) reduziu os níveis de nitrito e nitrato plasmático; (4) aumentou a ventilação e o volume corrente, sem alterações na frequência respiratória e (5) não foram observadas alterações na ureia e creatinina e morfologia dos rins. Conclusão: A acidose metabólica promoveu alterações na reatividade vascular, na função cardíaca e na ventilação pulmonar. Introduction: Acid-base disorders are common in medical practice and can range from simple acidosis or alkalosis to a complex and potentially fatal disorder. In a situation of acidosis or alkalosis, the ionic permeability and the cellular enzymatic functions can change, leading to dysfunction of several organs and systems. Metabolic acidosis (MA), a common clinical condition, is caused by a decrease in blood pH and bicarbonate concentration. It can occur acutely, lasting from a few hours to a day, or as a chronic condition, when normal pH cannot be fully restored. Acidosis, as a dominant type of acid-base disorder, is currently considered a factor causing cardiovascular dysfunction. Few researches on the effect of chronic metabolic acidosis on cardiac function, in vivo, are available. Thus, it is of great interest to study cardiac contractility in vivo and electrical changes in response to metabolic acidosis, in addition to vascular reactivity in arteries from acidotic animals. Aim: The aim of the present study was to demonstrate the effects of chronic metabolic acidosis (CMA) induced by the administration of ammonium chloride on cardiovascular and respiratory function, as well as the possible mechanisms involved. Methods: CMA was induced in Wistar rats by replacing water by solution of ammonium chloride 0.50M ad libitum plus 0.02M per gavage, for ten days. After ten days the animals were grouped for the remaining analyzes. Vascular reactivity was evaluated for several vasoactive drugs (Acetylcholine, Phenylephrine, Angiotensin II, Endothelin-1 and calcium ionophore - A23137) using the isolated organ chamber methodology. Some dose-response curves were performed in the presence of L-NAME. Cardiac function was also evaluated through echocardiogram for small animals, analyzing the following parameters: cardiac output, heart rate, systolic volume and systolic and diastolic shortening. The respiratory function was analyzed by plethysmography of the whole body and the parameters analyzed were ventilation, tidal volume and respiratory rate. In addition to the main analyzes mentioned above, nitric oxide analysis, photomiographs of kidneys and urea and creatinine analysis for renal function evaluation, were also performed. Results:Abstract Chronic metabolic acidosis (1) potentiated calcium ionophore-induced relaxation in a nitric oxide-dependent manner and with no changes for the other agonists tested; (2) reduced cardiac output and systolic volume, with no change in heart rate; (3) reduced nitrite and plasma nitrate levels; (4) increased ventilation and tidal volume without changes in respiratory rate and (5) no changes were observed in urea and creatinine and morphology of the kidneys. Conclusion: Metabolic acidosis promoted changes in vascular reactivity, cardiac function and pulmonary ventilation.

Background There is a definite association between antipsychotic drugs and arterial hypertension. However, endothelium functions are scarcely considered. This investigation was carried out to study the mechanisms involved in clozapine endothelium-dependent vascular reactivity. Methods The experimental animals were male Wistar rats with a mean age of 70–90 days (250–300 g). The endothelium-dependent vascular reactivity was studied by measuring the isometric force and then constructing clozapine concentration-response curves. The force registrations were obtained in the aorta rings with and without the endothelium precontracted with phenylephrine (PE10−6M) treatment; this followed incubation for 30 min in “organ chambers” with different inhibitors: l - NAME (nitric oxide/cGMP); indomethacin (PGI2/cAMP); tetraethylammonium (TEA), and specific hyperpolarization blockers (paxillin, apamin, glibenclamide). The data were presented as the mean ± standard error of the mean (SEM) and were compared by one-way ANOVA or two-way ANOVA followed by the Bonferroni post-test. Results The primary outcomes were: 1) Clozapine-induced endothelium-dependent relaxation was not inhibited by indomethacin, l -NAME, ODQ, and methylene blue (MB); 2) The combination of l -NAME + indomethacin partially prevented the relaxation; 3) Clozapine did not induce relaxation in vessels contracted with KCl; 4) TEA did not block the clozapine-induced relaxation in vessels precontracted with PE (10−6 M); 5) The potassium channel blockers paxillin and apamin did not prevent relaxation but glibenclamide did. Conclusion Concerning the mechanisms involved in clozapine endothelium-dependent vascular reactivity, the present study suggests that there is synergistic participation that probably occurs through a crosstalk mechanism of the cAMP, cGMPpathways and hyperpolarization.

The mechanisms by which pH influences vascular tone are not entirely understood, but evidence suggests that the endothelium is involved. Here, we aimed to study the in vitro vascular responses induced by extracellular hypercapnic acidification (HA), as well as the endothelium-dependent mechanisms that are involved in the responses. We bubbled a mixture of CO 2 (40%)/O 2 (60%) in an organ bath; we constructed a pH-response curve (pH range 7.4–6.6) and registered isometric force simultaneously. Aortic rings from rats were pre-contracted with phenylephrine (10 −6 M) and incubated for 30 min in the presence of different chemicals. The relaxations induced by HA occurred in rings with endothelium were: 1) Partially inhibited by indomethacin (10 −5 M) (PGI 2 pathway inhibitor); 2) Strongly inhibited by NO pathways: L-NAME (10 −4 M) and L-NMMA (10 −4 M) (no specific NO synthase inhibitors); L-Nil (10 −3 M) (specific iNOS inhibitor); ODQ (10 −4 M) (specific guanylate cyclase inhibitor), and; 4) Inhibit by tetraethylammonium (10 −3 M) (non-specific potassium channel inhibitor), glibenclamide (10 −5 M) (specific K AT P inhibitor), aminopyridine (10 −3 M) (specific Kv inhibitor) and apamin (10 −6 M) (specific SKCa inhibitor). In conclusion: 1) HA causes endothelium-dependent relaxation; 2) Indomethacin failed in blocking this relaxation, but the method limitation does not allow ruling out some prostanoid role; 3) The HA vessel relaxation is mediated via cGMP/NO, and; 4) The hyperpolarization occurs by the action of potassium SK Ca , K ATP and K v channels without relying on BK Ca channels.

Early cancer diagnosis, new therapies that increased survival of patients, besides the increasingly elderly population are some factors would be associated with possible cancer dissemination in patients under cardiopulmonary bypass (CPB) cardiac surgery. Also, the benefits, and risks, regarding long-term survival, have not yet been established. Therefore, cardiac surgery morbimortality may be superior in patients with cancer disease. Also, immunologic and inflammatory changes secondary to CPB can also increase tumor recurrence. After a brief introduction and CPB immunologic the two main topic subjects included: 1) Combined heart surgery and lung resection and; 2) Possible influence of neoplasia type. After observing the relative literature scarcity, we keep the opinion that “CPB has a modest association with cancer progression” and that “CPB and cancer dissemination should be a logical but unlikely association.”

Background: The diterpene Sclareol has antimicrobial action, cytotoxic and cytostatic effects and anti-tumor activities. However, researches on the cardiovascular system are scarce. Objective: This study was designed to investigate the mechanisms involved in the Sclareol cardiovascular effect in normotensive and hypertensive rats. Methods: The arterial hypertension was promoted using 2-kidneys 1-clip model in rats. The effect of sclareol on blood pressure was performed by using three dose (10, 20 and 40 mg/kg). Cumulative dose-response curves for Sclareol were determined for endothelium-intact and endothelium-denuded aortic rings in presence or absence of L-NAME and ODQ. The NOx levels were measure in the plasma sample. Results: The Sclareol administration in vivo caused a significant reduction in blood pressure in both groups. In vitro the sclareol promoted relaxation in aorta, with endothelium, pre-contracted to Phe. The inhibitors of the nitric oxide synthase and soluble guanylate cyclase were as efficient as the removal of endothelium, in inhibiting the Sclareol-induced relaxation. Otherwise, it was no change of NOx. Also, for unknown reasons, the Sclareol is not selective for hypertensive animals. Conclusion: The diterpene Sclareol showed in vivo hypotensive and in-vitro vasodilator effects; The chemiluminescence plasmatic NO analysis showed no significant difference between groups and The Sclareol exhibit better effect on normotensive than hypertensive animals to reduce blood pressure. It is concluded that the diterpenes metabolites would be a promising source prototype for the development of new agents in the cardiovascular therapy. Resumo Fundamento: O diterpeno Esclareol tem ação antimicrobiana, efeitos citotóxicos e citostáticos e atividades antitumorais. No entanto, pesquisas sobre o sistema cardiovascular são escassas. Objetivo: Este estudo foi desenvolvido para investigar os mecanismos envolvidos no efeito cardiovascular de Esclareol em ratos normotensos e hipertensos. Métodos: A hipertensão arterial foi promovida utilizando modelo de 2 clones de 1-clipe em ratos. O efeito do esclareol sobre a pressão arterial foi realizado utilizando três doses (10, 20 e 40 mg/kg). As curvas dose-resposta cumulativas para Esclareol foram determinadas para anéis aórticos endotélio-intactos e desprovidos de endotélio na presença ou ausência de L-NAME e ODQ. Os níveis de NOx foram medidos na amostra de plasma. Resultados: A administração de Esclareol in vivo causou uma redução significativa na pressão sanguínea em ambos os grupos. In vitro o esclareol promoveu relaxamento na aorta, com endotélio, pré-contraído a Phe. Os inibidores da óxido nítrico sintase e da guanilato ciclase solúvel foram tão eficientes quanto a remoção do endotélio, na inibição do relaxamento induzido por Esclareol. Por outra parte, não houve mudança de NOx. Além disso, por razões desconhecidas, o Sclareol não é seletivo para animais hipertensos. Conclusão: O diterpeno Esclareol apresentou efeitos hipotensores in vivo e vasodilatadores in vitro; A análise de NO plasmático por quimioluminescência não mostrou diferença significativa entre os grupos e O Esclareol exibe melhor efeito sobre os animais normotensos do que hipertensos para reduzir a pressão arterial. Conclui-se que os metabólitos de diterpenos seriam um protótipo de fonte promissora para o desenvolvimento de novos agentes na terapia cardiovascular.

Evidence-based review of the existing literature ultimately recommends stocking of Methylene Blue (MB) as an emergency antidote in the United States. The same is reported around the world in Japan, Greece, Italy and Canada. The observation that MB is always present as the main antidote required in emergency and critical care units calls for a revisit on its effects on the NO/cGMP system to reemphasize its multisystem actions. Therefore, the present review aimed to display the role of MB in emergency units, concerning: 1) Polytrauma and circulatory shock; 2) Neuroprotection, 3) Anaphylaxis and, 4) Overdose and poisoning.

Nonvalvular atrial fibrillation is associated with a 4- to 5-fold strokes increase and may be responsible for 15% to 20% of all strokes in the elderly. In this scenario, the left atrial appendage thrombus would be the associated with 90% of cases. The use of anticoagulants, percutaneous devices, and the left atrial appendage surgical exclusion is still an open discussion. For left atrial appendage procedures, relevant anatomic spatial relationships have to be emphasized, besides the chance of the normal physiological functioning would be eliminated with the proceedings. There are evidences that the left atrial appendage closure during routine cardiac surgery is significantly associated with an increased risk of early postoperative atrial fibrillation. Therefore, the purpose of this review is to focus basic aspects for continuous medical education. In summary, the rationale of this text is to emphasize anatomical and pharmacological aspects involved in the simple surgical exclusion of left atrial appendage under cardiopulmonary bypass. There are several operative techniques, but to conclude this revision it will present one of them based on the discussed basic sciences.

A modern concept considers acute coronary syndrome as an autoinflammatory disorder. From the onset to the healing stage, an endless inflammation has been presented with complex, multiple cross-talk mechanisms at the molecular, cellular, and organ levels. Inflammatory response following acute myocardial infarction has been well documented since the 1940s and 1950s, including increased erythrocyte sedimentation rate, the C-reactive protein analysis, and the determination of serum complement. It is surprising to note, based on a wide literature overview including the following 30 years (decades of 1960, 1970, and 1980), that the inflammatory acute myocardium infarction lost its focus, virtually disappearing from the literature reports. The reversal of this historical process occurs in the 1990s with the explosion of studies involving cytokines. Considering the importance of inflammation in the pathophysiology of ischemic heart disease, the aim of this paper is to present a conceptual overview in order to explore the possibility of curbing this inflammatory process.

To set up and test the feasibility of a handmade apparatus adapted for exhaled breath condensate (EBC) collection in medium-sized animals.The apparatus was produced using an 18-mm thick u-shaped borosilicate glass. The u-shaped tube body is 25 cm in diameter, and the horizontal portions are 12 cm in diameter. The base consists of a tube joint 14/20 or 14 mm thick by 20 cm in diameter, and has a length of 5 cm. This has a hole that is plugged for condensate flow to a 1.5 mL polypropylene microtube that stores the condensate during collection. Was placed inside a styrofoam box and immersed in crushed ice and salt to ensure cooling. The temperature was monitored and maintained throughout the collection at -10°C. One of the outputs of the u-shaped tube was connected to the expiratory limb of the ventilator.An experimental model of ALI, induced by oleic acid (OA) was adopted to determine the concentration of biomarkers of oxidative stress: malondialdehyde (MDA), glutathione (GSH), and nitrite/nitrate (NOx). The proposed model allows measurement of NOx, MDA, and GSH. However, the NOx and MDA levels in the EBC were not significant. It was only possible to observe an upward trend, which suggests a temporal evolution of the presence of these markers in the EBC.The EBC collection method adapted is effective to generate sufficient content that allows to determine the levels of different biomarkers, such as NOx, MDA, and GSH, that are involved in oxidative and inflammatory stress processes during respiratory diseases.

Objective: To examine if methylene blue (MB) can counteract or prevent protamine (P) cardiovascular effects. Methods: The protocol included five heparinized pig groups: Group Sham -without any drug; Group MB - MB 3 mg/kg infusion; Group P - protamine; Group P/MB - MB after protamine; Group MB/P - MB before protamine. Nitric oxide levels were obtained by the nitric oxide/ozone chemiluminescence method, performed using the Nitric Oxide Analizer 280i (Sievers, Boulder, CO, USA). Malondialdehyde plasma levels were estimated using the thiobarbiturate technique. Results: 1) Groups Sham and MB presented unchanged parameters; 2) Group P - a) Intravenous protamine infusion caused mean arterial pressure decrease and recovery trend after 25-30 minutes, b) Cardiac output decreased and remained stable until the end of protamine injection, and c) Sustained systemic vascular resistance increased until the end of protamine injection; 3) Methylene blue infusion after protamine (Group P/MB) - a) Marked mean arterial pressure decreased after protamine, but recovery after methylene blue injection, b) Cardiac output decreased after protamine infusion, recovering after methylene blue infusion, and c) Sustained systemic vascular resistance increased after protamine infusion and methylene blue injections; 4) Methylene blue infusion before protamine (Group MB/P) - a) Mean arterial pressure decrease was less severe with rapid recovery, b) After methylene blue, there was a progressive cardiac output increase up to protamine injection, when cardiac output decreased, and c) Sustained systemic vascular resistance decreased after protamine, followed by immediate Sustained systemic vascular resistance increase; 5) Plasma nitrite/nitrate and malondialdehyde values did not differ among the experimental groups. Conclusion: Reviewing these experimental results and our clinical experience, we suggest methylene blue safely prevents and treats hemodynamic protamine complications, from the endothelium function point of view.

Made available in DSpace on 2018-12-11T16:42:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01. Added 1 bitstream(s) on 2021-07-15T15:02:13Z : No. of bitstreams: 1 S0102-86502016001300045.pdf: 340806 bytes, checksum: 83f04b5dd120d91f33c40fba2152afb8 (MD5) PURPOSE: Cardiopulmonary bypass (CPB) procedures are thought to activate systemic inflammatory reaction syndrome (SIRS). Strategies to curb systemic inflammation have been previously described. However, none of them is adequate, since “curbing” the extent of the inflammatory response requires a multimodal approach. The aim of the present mini-review is to discuss the main key points about the main principles in cardiopulmonary bypass curbing inflammation. METHODS: No systematic literature search (MEDLINE) and extracted data from the accumulated experience of the authors. The preconceived idea of an association between severe inflammation and coagulation disorders is reviewed. Also, some fundamental concepts, CPB inflammatory biomarkers, the vasoplegic syndrome and the need forindividual CPB protocols for children, diabetes and old patients, are discussed. CONCLUSION: The ways in which surgical technique (atraumatic vein harvest, biocompatibility and shear resistance of the circuit, monitoring, minimizing organ ischemia, minimal cross-clamping trauma, and blood management) are thought to curb SIRS induced by CPB and affect positively the patient outcome.Improved patient outcomes are strongly associated with these modalities of care, more than single or combinatorial drug strategies (aprotinin, tranexamic acid, pentoxifylline) or CPB modalities (minicircuits, heparin-coated circuits, retrograde autologous prime). Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (FMRP-USP) Department of Animal Pathology Veterinary School São Paulo State University (UNESP) Department of Animal Pathology Veterinary School São Paulo State University (UNESP)

O uso de mostras animais é importante na pesquisa otológica e o conhecimento da anatomia de sua orelha permite sua utilização adequada. OBJETIVO: Estudar a anatomia da orelha da cobaia e do rato por microscopia óptica de luz (MOL) e microscopia eletrônica de varredura (MEV) e suas vantagens anatômicas na pesquisa otológica básica. MATERIAL E MÉTODO: Os ossos temporais, as bulas timpânicas e cócleas de três cobaias e ratos albinos foram fotografados e analisados ao MOL e MEV. RESULTADOS: O rato não é tão simples de manipular como a cobaia, e freqüentemente apresenta otite média. O rato apresenta uma junção frágil da bula timpânica, duas e meia espiras na cóclea e a membrana timpânica não veda todo o conduto auditivo externo. A cobaia possui uma bula inteiriça, martelo e bigorna fundidos e três e meia espiras na cóclea. Pela MEV a cobaia e o rato possuem Membrana Tectória, Membrana de Raissner e o Órgão de Corti. As Células de Hensen estão presentes somente na cobaia. CONCLUSÃO: A cobaia foi considerada de fácil manipulação para a microdissecção, pelo tamanho e rigidez do osso temporal, e para experimentos cirúrgicos envolvendo o estribo, janela oval e a membrana timpânica. Pela MEV nota-se semelhança entre cobaia e rato, podendo ambos serem utilizados em estudos da orelha interna.The use of animal samples is important in otologic research and understanding the anatomy of their ears help make proper use of them in research projects. AIM: to study guinea pig's and rat's ears under light microscopy(LM) and scanning electron microscopy(SEM) and understand their anatomical advantages in basic otologic research. MATERIALS AND METHODS: The temporal bones, tympanic bullas and cochleas from three albino guinea pigs and rats were photographed and analyzed under LM and SEM. RESULTS: Rats aren't as simple to handle as guinea pigs, and often present with otitis media. Rats have a fragile junction of the tympanic bulla, two and half turns in the cochlea, and their tympanic membranes do not seal off the entire external auditory canal. Guinea pigs have full bullas, their incus and malleus are fused and they have three and half cochlear turns. Under SEM, guinea pigs and rats have Tectori Membrane, Raissner's Membrane and the Organ of Corti. Only guinea pigs have Hensen's Cells. CONCLUSION: Guinea pigs were considered easy to handle for microdissection purposes because of the size and robustness of their temporal bones, and for surgical experiments involving the stapes, the oval window and the tympanic membrane. Under SEM there are similarities guinea pigs and rats, and both can be used in inner ear studies.

The present text was motivated by the difficulties faced by our postgraduate students when using airways studies protocols and will take into consideration the three mechanisms of relaxation: (I) guanosine 3,5-cyclic monophosphate (cGMP)/NO-dependent; (II) adenosine 3,5-cyclic monophosphate (cAMP)/PGI2-dependent, and (III) hyperpolarization-dependent. Tracheal rings are studied in an organ bath containing a gassed physiological salt solution, usually at a temperature of 37 °C. An agent or procedure that causes contraction [acetylcholine (Ach) or metacholine] of the smooth muscle is needed before study airway dilator drugs. The presented airways studies protocols are useful to study the bronchial epithelial-dependent reactivity.

Validation of transendocardial injection as a method for delivering therapeutic agents to the diseased heart is increasing. Puncture heart biopsies should re-emerge as a possible alternative method to allow access to the myocardium and implantable biomaterial for cell therapy. Therefore, this work aims to present a percutaneous puncture device for biopsy and intramyocardial biomaterial injection, standardize the technique and attest to the safety of the method. The adaptation consists of creating myocardial microlesions that allow for better fixation of stem cells. The objective of this technical note covers only the development of the needle and the histological quality of the biopsies. It has not been used in humans yet.

Metabolic acidosis has profound effects on vascular tone. This study investigated the in vivo effects of acute metabolic acidosis (AMA) and chronic metabolic acidosis (CMA) on hemodynamic parameters and endothelial function. CMA was induced by ad libitum intake of 1% NH4Cl for 7 days, and AMA was induced by a 3-h infusion of 6 M NH4Cl (1 mL/kg, diluted 1:10). Phenylephrine (Phe) and acetylcholine (Ach) dose-response curves were performed by venous infusion with simultaneous venous and arterial blood pressure monitoring. Plasma nitrite/nitrate (NOx) was measured by chemiluminescence. The CMA group had a blood pH of 7.15±0.03, which was associated with reduced bicarbonate (13.8±0.98 mmol/L) and no change in the partial pressure of arterial carbon dioxide (PaCO2). The AMA group had a pH of 7.20±0.01, which was associated with decreases in bicarbonate (10.8±0.54 mmol/L) and PaCO2 (47.8±2.54 to 23.2±0.74 mmHg) and accompanied by hyperventilation. Phe or ACh infusion did not affect arterial or venous blood pressure in the CMA group. However, the ACh infusion decreased the arterial blood pressure (ΔBP: -28.0±2.35 mm Hg [AMA] to -4.5±2.89 mmHg [control]) in the AMA group. Plasma NOx was normal after CMA but increased after AMA (25.3±0.88 to 31.3±0.54 μM). These results indicate that AMA, but not CMA, potentiated the Ach-induced decrease in blood pressure and led to an increase in plasma NOx, reinforcing the effect of pH imbalance on vascular tone and blood pressure control.