RESUMO
The endocannabinoid neurotransmission acting via local CB1 receptor in the bed nucleus of the stria terminalis (BNST) has been implicated in behavioral and physiological responses to emotional stress. However, the neural network related to this control is poorly understood. In this sense, the lateral hypothalamus (LH) is involved in stress responses, and BNST GABAergic neurons densely innervate this hypothalamic nucleus. However, a role of BNST projections to the LH in physiological responses to stress is unknown. Therefore, using male rats, we investigated the role of LH GABAergic neurotransmission in the regulation of cardiovascular responses to stress by CB1 receptors within the BNST. We observed that microinjection of the selective CB1 receptor antagonist AM251 into the BNST decreased the number of Fos-immunoreactive cells within the LH of rats submitted to acute restraint stress. Treatment of the BNST with AM251 also enhanced restraint-evoked tachycardia. Nevertheless, arterial pressure increase and sympathetically-mediated cutaneous vasoconstriction to restraint was not affected by CB1 receptor antagonism within the BNST. The effect of AM251 in the BNST on restraint-evoked tachycardia was abolished in animals pretreated with the selective GABAA receptor antagonist SR95531 in the LH. These results indicate that regulation of cardiovascular responses to stress by CB1 receptors in the BNST is mediated by GABAergic neurotransmission in the LH. Present data also provide evidence of the BNST endocannabinoid neurotransmission as a mechanism involved in LH neuronal activation during stressful events.
Assuntos
Endocanabinoides/fisiologia , Região Hipotalâmica Lateral/fisiologia , Angústia Psicológica , Núcleos Septais/fisiologia , Animais , Antagonistas de Receptores de Canabinoides/administração & dosagem , Antagonistas GABAérgicos/administração & dosagem , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/fisiologia , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Região Hipotalâmica Lateral/efeitos dos fármacos , Masculino , Modelos Neurológicos , Piperidinas/administração & dosagem , Pirazóis/administração & dosagem , Piridazinas/administração & dosagem , Ratos , Ratos Wistar , Núcleos Septais/efeitos dos fármacos , Estresse Psicológico/fisiopatologia , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , Taquicardia/fisiopatologiaRESUMO
AIMS: To evaluate the systemic changes and autonomic cardiocirculatory control of awaken rats chronically exposed to the cigarette smoke (CS) of 1 or 2 cigarettes/day. MAIN METHODS: Rats were exposed to clean air (control) or cigarette smoke of 1 (CS1) or 2 (CS2) cigarettes/animal/day for 30 days. Then, arterial pressure (AP) and heart rate (HR) were recorded in conscious rats to assess spontaneous baroreflex sensitivity and HR and AP variabilities. Evoked baroreflex and cardiac autonomic tone were evaluated by vasoactive drugs and autonomic blockers, respectively. In another group, ventilatory and cardiovascular parameters were recorded under hypoxia and hypercapnia stimulus. At the end of protocols, heart, lung, kidneys and liver were collected for histological analysis. KEY FINDINGS: Rats exposed to CS showed morphological changes, being more evident in the CS2 group. Also, less weight gain and cardiac hypertrophy were prominent in CS2 rats. Basal AP and HR, spontaneous baroreflex sensitivity and cardiovascular variabilities were similar among groups. CS exposure progressively blunted the bradycardia response to phenylephrine (-2.2 ± 0.1 vs. -1.7 ± 0.2 vs. -1.5 ± 0.2) while the tachycardia response to sodium nitroprusside was slightly increased compared to control. Vagal tone was not affected by CS, but CS2 rats exhibited higher sympathetic tone (-25 ± 4 vs. -28 ± 4 vs. -56 ± 9) and lower intrinsic HR (411 ± 4 vs. 420 ± 8 vs. 390 ± 6). Exposure to CS of 2 cigarettes also exacerbated the reflex cardiovascular and ventilatory responses to hypoxia and hypercapnia. SIGNIFICANCE: CS exposure for 30 days promoted systemic changes and autonomic cardiocirculatory dysfunction in rats depending on the daily exposure dose.
Assuntos
Sistema Nervoso Autônomo/efeitos dos fármacos , Sistema Cardiovascular/efeitos dos fármacos , Fumar Cigarros/efeitos adversos , Animais , Sistema Nervoso Autônomo/fisiopatologia , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Bradicardia/fisiopatologia , Sistema Cardiovascular/fisiopatologia , Relação Dose-Resposta a Droga , Coração/fisiopatologia , Frequência Cardíaca/fisiologia , Masculino , Ratos , Ratos Wistar , Reflexo , Taquicardia/fisiopatologia , Nervo Vago/fisiopatologiaRESUMO
The lateral hypothalamus (LH) is implicated in the physiological and behavioral responses during stressful events. However, the local neurochemical mechanisms related to control of stress responses by this hypothalamic area are not completely understood. Therefore, in this study we evaluated the involvement of CRFergic neurotransmission acting through the CRF1 receptor within the LH in cardiovascular responses evoked by an acute session of restraint stress in rats. For this, we investigated the effect of bilateral microinjection of different doses (0.01, 0.1 and 1 nmol/100 nL) of the selective CRF1 receptor antagonist CP376395 into the LH on arterial pressure and heart rate increases and decrease in tail skin temperature evoked by acute restraint stress. We found that all doses of the CRF1 receptor antagonist microinjected into the LH decreased the restraint-evoked tachycardia, but without affecting the arterial pressure and tail skin temperature responses. Additionally, treatment of the LH with CP376395 at the doses of 0.1 and 1 nmol/100 nL increased the basal values of both heart rate and arterial pressure, whereas the dose of 0.1 nmol/100 nL decreased the skin temperature. Taken together, these findings indicate that CRFergic neurotransmission in the LH, acting through activation of local CRF1 receptors, plays a facilitatory role in the tachycardia observed during aversive threats, but without affecting the pressor and tail skin temperature responses. Our results also provide evidence that LH CRFergic neurotransmission in involved in tonic maintenance of cardiovascular function.
Assuntos
Hormônio Liberador da Corticotropina/metabolismo , Região Hipotalâmica Lateral/fisiologia , Angústia Psicológica , Transmissão Sináptica/fisiologia , Taquicardia/fisiopatologia , Animais , Frequência Cardíaca/fisiologia , Masculino , Ratos , Ratos Wistar , Receptores de Hormônio Liberador da Corticotropina/metabolismo , Restrição Física , Taquicardia/etiologiaAssuntos
Síndrome do QT Longo/terapia , Marca-Passo Artificial , Síndrome do Nó Sinusal/terapia , Taquicardia/fisiopatologia , Adulto , Algoritmos , Estimulação Cardíaca Artificial , Criança , Exercício Físico , Feminino , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Lactente , Síndrome do QT Longo/fisiopatologia , Síndrome do Nó Sinusal/fisiopatologiaRESUMO
El diagnóstico electrocardiográfico correcto de la causa de una taquicardia de complejo QRS ancho (TCA) es fundamental, ya que tanto el manejo, como el pronóstico del paciente, es diferente según su etiología, y define el estudio que debemos realizar. Numerosos criterios y algoritmos han sido descritos para diferenciar el origen de estas taquicardias. Sin embargo, muchos de estos son complejos y difíciles de aplicar para el médico menos experimentado. Esto es particularmente importante en los servicios de emergencia, donde se necesita una definición rápida que permita un manejo agudo apropiado. En la presente revisión analizamos los diferentes mecanismos de las TCA y los principales criterios diagnósticos en el ECG, reforzando, especialmente, aquellos de aplicación rápida y de alto rendimiento diagnóstico.
The correct electrocardiographic diagnosis of the cause of a wide QRS complex tachycardia (WCT) is essential since both management and prognosis of the patient. The correct electrocardiographic diagnosis of the cause of a wide QRS complex tachycardia (WCT) is essential since both management and prognosis is different according to its etiology and defines the study that we should perform. Numerous criteria and algorithms have been described to differentiate the origin of these tachycardias. However, many of these are complex and difficult to apply to the less experienced doctor. This is particularly important in emergency rooms, where a rapid definition is needed to allow proper therapy. In this review we analyze the different mechanisms of WCT and the main EKG diagnostic criteria, emphasizing those which can be applied rapidly and have high diagnostic value.
Assuntos
Humanos , Taquicardia Ventricular/diagnóstico , Taquicardia/diagnóstico , Taquicardia/fisiopatologia , Algoritmos , Taquicardia Supraventricular/diagnóstico , Taquicardia Supraventricular/fisiopatologia , Síndromes de Pré-Excitação , Bloqueio de Ramo , Taquicardia Ventricular/fisiopatologia , Diagnóstico Diferencial , EletrocardiografiaRESUMO
Our group has previously shown in pithed rats that the cardiac sympathetic drive, which produces tachycardic responses, is inhibited by 5-HT via the activation of prejunctional 5-HT1B/1D/5 receptors. Interestingly, when 5-HT2 receptors are chronically blocked with sarpogrelate, the additional role of cardiac sympatho-inhibitory 5-HT1F receptors is unmasked. Although 5-HT2 receptors mediate tachycardia in rats, and the chronic blockade of 5-HT2 receptors unmasked 5-HT7 receptors mediating cardiac vagal inhibition, the role of 5-HT7 receptors in the modulation of the cardiac sympathetic tone remains virtually unexplored. On this basis, male Wistar rats were pretreated during 14 days with sarpogrelate (a 5-HT2 receptor antagonist) in drinking water (30 mg/kg/day; sarpogrelate-pretreated group) or equivalent volumes of drinking water (control group). Subsequently, the rats were pithed to produce increases in heart rate by either electrical preganglionic spinal (C7 -T1 ) stimulation of the cardiac sympathetic drive or iv administration of exogenous noradrenaline. The iv continuous infusion of AS-19 (a 5-HT7 receptor agonist; 10 µg/kg/min) (i) inhibited the tachycardic responses to sympathetic stimulation, but not those to exogenous noradrenaline only in sarpogrelate-pretreated rats. This inhibition was completely reversed by SB258719 (a selective 5-HT7 receptor antagonist; 1 mg/kg, iv) or glibenclamide (an ATP-sensitive K+ channel blocker; 20 mg/kg, iv). These results suggest that chronic 5-HT2 receptor blockade uncovers a cardiac sympatho-inhibitory mechanism mediated by 5-HT7 receptors, involving a hyperpolarization due to the opening of ATP-sensitive K+ channels. Thus, these findings support the role of 5-HT7 receptors in the modulation of the cardiac sympathetic neurotransmission.
Assuntos
Fibras Adrenérgicas/fisiologia , Receptores 5-HT2 de Serotonina/fisiologia , Receptores de Serotonina/fisiologia , Antagonistas do Receptor 5-HT2 de Serotonina/uso terapêutico , Succinatos/uso terapêutico , Taquicardia/prevenção & controle , Fibras Adrenérgicas/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Estimulação Elétrica/efeitos adversos , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Masculino , Norepinefrina/toxicidade , Ratos , Ratos Wistar , Antagonistas do Receptor 5-HT2 de Serotonina/farmacologia , Succinatos/farmacologia , Simpatomiméticos/toxicidade , Taquicardia/etiologia , Taquicardia/fisiopatologiaRESUMO
According to the World Health Organization, 98% of fatal dengue cases can be prevented; however, endemic countries such as Colombia have recorded higher case fatality rates during recent epidemics. We aimed to identify the predictors of mortality that allow risk stratification and timely intervention in patients with dengue. We conducted a hospital-based, case-control (1:2) study in two endemic areas of Colombia (2009-2015). Fatal cases were defined as having either 1) positive serological test (IgM or NS1), 2) positive virological test (RT-PCR or viral isolation), or 3) autopsy findings compatible with death from dengue. Controls (matched by state and year) were hospitalized nonfatal patients and had a positive serological or virological dengue test. Exposure data were extracted from medical records by trained staff. We used conditional logistic regression (adjusting for age, gender, disease's duration, and health-care provider) in the context of multiple imputation to estimate exposure to case-control associations. We evaluated 110 cases and 217 controls (mean age: 35.0 versus 18.9; disease's duration pre-admission: 4.9 versus 5.0 days). In multivariable analysis, retro-ocular pain (odds ratios [OR] = 0.23), nausea (OR = 0.29), and diarrhea (OR = 0.19) were less prevalent among fatal than nonfatal cases, whereas increased age (OR = 2.46 per 10 years), respiratory distress (OR = 16.3), impaired consciousness (OR = 15.9), jaundice (OR = 32.2), and increased heart rate (OR = 2.01 per 10 beats per minute) increased the likelihood of death (AUC: 0.97, 95% confidence interval: 0.96, 0.99). These results provide evidence that features of severe dengue are associated with higher mortality, which strengthens the recommendations related to triaging patients in dengue-endemic areas.
Assuntos
Diarreia/diagnóstico , Icterícia/diagnóstico , Náusea/diagnóstico , Síndrome do Desconforto Respiratório/diagnóstico , Dengue Grave/diagnóstico , Taquicardia/diagnóstico , Adolescente , Adulto , Anticorpos Antivirais/sangue , Estudos de Casos e Controles , Colômbia , Vírus da Dengue/imunologia , Vírus da Dengue/isolamento & purificação , Diarreia/mortalidade , Diarreia/fisiopatologia , Diarreia/virologia , Doenças Endêmicas , Feminino , Cefaleia , Humanos , Imunoglobulina M/sangue , Icterícia/mortalidade , Icterícia/fisiopatologia , Icterícia/virologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Náusea/mortalidade , Náusea/fisiopatologia , Náusea/virologia , Síndrome do Desconforto Respiratório/mortalidade , Síndrome do Desconforto Respiratório/fisiopatologia , Síndrome do Desconforto Respiratório/virologia , Medição de Risco , Dengue Grave/mortalidade , Dengue Grave/fisiopatologia , Dengue Grave/virologia , Análise de Sobrevida , Taquicardia/mortalidade , Taquicardia/fisiopatologia , Taquicardia/virologiaRESUMO
Commonly reported complications of hepatic cysts are spontaneous hemorrhage, rupture into the peritoneal cavity, infection and compression of the biliary tree however cardiac complications are not commonly reported. We are presenting a case of a large liver cyst presenting with right atrial and ventricular inflow tract impingement resulting in cardiac symptoms. A 68 year-old Hispanic female presented with one month of fatigue and shortness of breath after household work and walking less than one block, right upper quadrant pain and weight loss. She had history of multiple hepatic cysts for more than 12 years, well-controlled diabetes and hypertension. Examination of the heart revealed tachycardia with regular heart sounds. There were no murmurs. She had tenderness in her right upper quadrant on palpation and an enlarged smooth liver. Rest of physical examination was unremarkable. CT scan of the abdomen showed multiple non-enhancing liver cysts in both lobes, with the largest measuring 12 x 15 x 17 cm which was significantly increased from her baseline of 7 x 8 x 10 cm in 2003. Echocardiogram showed normal left ventricular ejection fraction, grade 1 diastolic dysfunction and a hepatic cyst impinging RA and RV inflow tract. She had successful laparoscopic enucleation of liver cyst and subsequent relief from tachycardia, fatigue and shortness of breath. In conclusion, this case illustrates that hepatic cysts may become symptomatic after remaining quiescent for an extended period. They may present with unusual symptoms and clinicians should be mindful of rare complications, such as in this case.
Assuntos
Cistos/complicações , Hepatopatias/complicações , Taquicardia/etiologia , Disfunção Ventricular Direita/etiologia , Obstrução do Fluxo Ventricular Externo/etiologia , Idoso , Função do Átrio Direito , Cistos/diagnóstico por imagem , Cistos/cirurgia , Drenagem , Feminino , Humanos , Laparoscopia , Hepatopatias/diagnóstico por imagem , Hepatopatias/cirurgia , Taquicardia/diagnóstico por imagem , Taquicardia/fisiopatologia , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Disfunção Ventricular Direita/diagnóstico por imagem , Disfunção Ventricular Direita/fisiopatologia , Função Ventricular Direita , Obstrução do Fluxo Ventricular Externo/diagnóstico por imagem , Obstrução do Fluxo Ventricular Externo/fisiopatologiaRESUMO
Prior evidence indicates that ghrelin is involved in the integration of cardiovascular functions and behavioral responses. Ghrelin actions are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), which is expressed in peripheral tissues and central areas involved in the control of cardiovascular responses to stress. AIMS: In the present study, we assessed the role of ghrelin - GHS-R1a axis in the cardiovascular reactivity to acute emotional stress in rats. MAIN METHODS AND KEY FINDINGS: Ghrelin potentiated the tachycardia evoked by restraint and air jet stresses, which was reverted by GHS-R1a blockade. Evaluation of the autonomic balance revealed that the sympathetic branch modulates the ghrelin-evoked positive chronotropy. In isolated hearts, the perfusion with ghrelin potentiated the contractile responses caused by stimulation of the beta-adrenergic receptor, without altering the amplitude of the responses evoked by acetylcholine. Experiments in isolated cardiomyocytes revealed that ghrelin amplified the increases in calcium transient changes evoked by isoproterenol. SIGNIFICANCE: Taken together, our results indicate that the Ghrelin-GHS-R1a axis potentiates the magnitude of stress-evoked tachycardia by modulating the autonomic nervous system and peripheral mechanisms, strongly relying on the activation of cardiac calcium transient and beta-adrenergic receptors.