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1.
Zhongguo Zhong Yao Za Zhi ; 45(2): 436-443, 2020 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-32237329

RESUMO

To analyze the efficacy and safety of Shensong Yangxin Capsules in treatment of bradycardia combined with premature beat. Databases, such as CNKI, VIP, WanFang, SinoMed, PubMed, Cochrane Library, ClinicalTrials were retrieved by computers for relevant randomized controlled trials of Shensong Yangxin Capsules in treatment of bradycardia combined with premature beat. Two researchers independently screened out the literatures, extracted data according to the inclusion criteria, and applied the Risk of Bias assessment tool in assessing the methodological quality. The Cochrane systematic evaluation software RevMan 5.3 was used for data analysis. Totally 9 randomized controlled trials including 706 subjects were included. The intervention measure was the single administration with Shensong Yangxin Capsules, and the control measure was the blank control. The results showed that Shensong Yangxin Capsules had an obvious effect on average heart rate(MD=6.59, 95%CI[3.87, 9.31], I~2=90%), premature beat efficacy(RR=1.72, 95%CI[1.53, 1.93], I~2=0%), heart rate efficacy(RR=1.74, 95%CI[1.40, 2.17], I~2=47%), and objective efficacy(RR=1.50, 95%CI[1.31, 1.70], I~2=31%). Eight studies reported safety events, with no significant adverse reaction. In conclusion, the single administration with Shensong Yangxin Capsules may have a certain effect in improving heart rate, controlling premature beats and alleviating clinical symptoms in patients with bradycardia combined with premature beat, with no obvious adverse reaction. Shensong Yangxin Capsules can be used in clinic. This potential conclusion needs to be confirmed in future trials using rigorous methodology.


Assuntos
Bradicardia/tratamento farmacológico , Complexos Cardíacos Prematuros/tratamento farmacológico , Medicamentos de Ervas Chinesas/uso terapêutico , Cápsulas , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto
2.
Am J Nurs ; 120(5): 45-47, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32332366

RESUMO

Editor's note: This is the first in a new series on electrocardiography (ECG) interpretation. Nurses in all settings should know the basics, as medications and physiological changes can cause cardiac arrhythmias. Each article will start with a brief case scenario and an ECG strip and then take you step by step through analyzing the heart rhythm.


Assuntos
Bradicardia , Eletrocardiografia , Fadiga/etiologia , Tiroxina/uso terapêutico , Bradicardia/diagnóstico , Bradicardia/tratamento farmacológico , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade
3.
BMJ Case Rep ; 12(12)2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31796445

RESUMO

Trigeminocardiac reflex (TCR) is a brainstem reflex triggered by the stimulation of any branch of the fifth cranial nerve along its course, presenting as a reduction in heart rate and blood pressure. Oculocardiac reflex is a well-known subtype of TCR. In the case reported here, remarkable arrhythmia followed by bradycardia occurred suddenly in a healthy patient undergoing orthognathic surgery. The heart rhythm recovered when the surgical manipulation ceased, but bradycardia was reproduced when the surgery resumed. This case of TCR is unique in that remarkable arrhythmia first appeared and led to bradycardia; accordingly, intravenous lidocaine and an anticholinergic agent were administered simultaneously instead of anticholinergic agents alone, and were protective. Although TCR rarely occurs during orthognathic surgery, clinicians should be aware of its possibility and able to judge and manage it promptly.


Assuntos
Bradicardia/etiologia , Complicações Intraoperatórias/etiologia , Procedimentos Cirúrgicos Ortognáticos/efeitos adversos , Osteotomia Sagital do Ramo Mandibular/efeitos adversos , Reflexo Trigêmino-Cardíaco/fisiologia , Administração Intravenosa , Antiarrítmicos/administração & dosagem , Bradicardia/tratamento farmacológico , Antagonistas Colinérgicos/administração & dosagem , Eletrocardiografia , Humanos , Complicações Intraoperatórias/tratamento farmacológico , Lidocaína/administração & dosagem , Masculino , Procedimentos Cirúrgicos Ortognáticos/métodos , Osteotomia Sagital do Ramo Mandibular/métodos , Reflexo Trigêmino-Cardíaco/efeitos dos fármacos , Adulto Jovem
5.
Arq Bras Cardiol ; 113(5): 925-932, 2019 11.
Artigo em Inglês, Português | MEDLINE | ID: mdl-31482987

RESUMO

BACKGROUND: D-limonene (DL) is a monoterpene and is the major component in the essential oil of citrus fruit. It presents antihyperglycemic and vasodilatation activities. OBJECTIVES: This study evaluated the cardiovascular effects and potential antiarrhythmic of DL in rats. METHODS: Hemodynamic and electrocardiographic (ECG) parameters were measured in male Wistar rats, which under anesthesia had been cannulated in the abdominal aorta and lower vena cava and had electrodes subcutaneously implanted. In the in vitro approach, the heart was removed and perfused using the Langendorff technique. The significance level adopted was 5% (p < 0.05). RESULTS: DL, in doses of 10, 20, and 40 mg/kg (i.v), produced intense and persistent bradycardia associated with hypotension. Bradycardia with prolonged QTc was observed in the ECG in vivo recording. In the in vivo model of arrhythmia induced by Bay K8644, DL (10 mg/kg) decreased the arrhythmia score from 15.33 ± 3.52 to 4.0 ± 2.64 u.a (p < 0.05, n = 4). In isolated perfused hearts, DL (10-3 M) promoted significant reductions in heart rate (from 228.6 ± 8.5 ms to 196.0 ± 9.3 bpm; p < 0.05) and left ventricular development pressure (from 25.2 ± 3.4 to 5.9 ± 1.8 mmHg; n = 5, p < 0.05). CONCLUSIONS: DL produces bradycardia and antiarrhythmic activity in rat heart.


Assuntos
Antiarrítmicos/uso terapêutico , Arritmias Cardíacas/tratamento farmacológico , Bradicardia/tratamento farmacológico , Limoneno/uso terapêutico , Animais , Antiarrítmicos/farmacologia , Arritmias Cardíacas/induzido quimicamente , Arritmias Cardíacas/diagnóstico , Pressão Sanguínea/efeitos dos fármacos , Bradicardia/diagnóstico , Eletrocardiografia , Frequência Cardíaca/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Hipotensão , Preparação de Coração Isolado , Limoneno/farmacologia , Masculino , Modelos Animais , Ratos Wistar , Pressão Ventricular/efeitos dos fármacos
6.
Int Heart J ; 60(5): 1222-1225, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31484879

RESUMO

Bradycardia is a common complication at the early postoperative period after heart transplantation (HT). The heart rate (HR) usually recovers within a few weeks; however, several patients need a temporary pacemaker or chronotropic agents to stabilize their hemodynamics. Here, we report the first case of transient bradycardia associated with hemodynamic deterioration following HT, which was successfully treated with cilostazol, a phosphodiesterase-3-inhibiting agent. A 59-year-old man received HT for advanced heart failure due to ischemic cardiomyopathy. General fatigue persisted even after the HT. His HR was around 60 beats per minute (bpm) with sinus rhythm. Echocardiography showed no abnormal findings. Right heart catheterization showed that the cardiac index (CI) was 1.9 L/minute/m2. Continuous intravenous infusion of isoproterenol (0.003 µg/kg/minute) increased the HR to 80 bpm and CI to 2.7 L/minute/m2 and improved his symptoms. Isoproterenol was switched to oral administration of cilostazol (100 mg, twice a day), which maintained the HR at around 80 bpm and CI of 2.5 L/minute/m2. The patient's HR gradually recovered and cilostazol could be discontinued three months after the HT. Oral administration of cilostazol can be a therapeutic option for patients with sinus bradycardia following HT, who need positive chronotropic support.


Assuntos
Bradicardia/tratamento farmacológico , Cilostazol/uso terapêutico , Insuficiência Cardíaca/cirurgia , Transplante de Coração/efeitos adversos , Bradicardia/diagnóstico por imagem , Bradicardia/etiologia , Débito Cardíaco/efeitos dos fármacos , Eletrocardiografia/métodos , Seguimentos , Insuficiência Cardíaca/diagnóstico , Transplante de Coração/métodos , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/tratamento farmacológico , Edema Pulmonar/diagnóstico por imagem , Edema Pulmonar/etiologia , Edema Pulmonar/fisiopatologia , Radiografia Torácica/métodos , Fatores de Tempo , Resultado do Tratamento
8.
Am J Emerg Med ; 37(8): 1554-1561, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31060863

RESUMO

INTRODUCTION: Patients with acute myocardial infarction (AMI) may suffer several complications after the acute event, including dysrhythmias and heart failure (HF). These complications place patients at risk for morbidity and mortality. OBJECTIVE: This narrative review evaluates literature and guideline recommendations relevant to the acute emergency department (ED) management of AMI complicated by dysrhythmia or HF, with a focus on evidence-based considerations for ED interventions. DISCUSSION: Limited evidence exists for ED management of dysrhythmias in AMI due to relatively low prevalence and frequent exclusion of patients with active cardiac ischemia from clinical studies. Management decisions for bradycardia in the setting of AMI are determined by location of infarction, timing of the dysrhythmia, rhythm assessment, and hemodynamic status of the patient. Atrial fibrillation is common in the setting of AMI, and caution is warranted in acute rate control for rapid ventricular rate given the possibility of compensation for decreased ventricular function. Regular wide complex tachycardia in the setting of AMI should be managed as ventricular tachycardia with electrocardioversion in the majority of cases. Management directed towards HF from left ventricular dysfunction in AMI consists of noninvasive positive pressure ventilation, nitroglycerin therapy, and early cardiac catheterization. Norepinephrine is the first line vasopressor for patients with cardiogenic shock and hypoperfusion on clinical examination. Early involvement of a multi-disciplinary team is recommended when caring for patients in cardiogenic shock. CONCLUSIONS: This review discusses considerations of ED management of dysrhythmias and HF associated with AMI.


Assuntos
Fibrilação Atrial/terapia , Bradicardia/tratamento farmacológico , Bloqueio Cardíaco/terapia , Insuficiência Cardíaca/terapia , Infarto do Miocárdio/complicações , Taquicardia Ventricular/terapia , Fibrilação Atrial/etiologia , Bradicardia/etiologia , Medicina de Emergência , Bloqueio Cardíaco/etiologia , Bloqueio Cardíaco/mortalidade , Insuficiência Cardíaca/etiologia , Humanos , Guias de Prática Clínica como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Choque Cardiogênico/complicações , Taquicardia Ventricular/etiologia
9.
Medicine (Baltimore) ; 98(19): e15536, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31083205

RESUMO

RATIONALE: Sinus bradycardia refers to a sinus heart rate <60 bpm. Cardiac sinus arrests refer to the omission of atrial activation caused by transient cessation of impulse generation at the sinoatrial node. Normally, drugs such as atropine, isoproterenol, dopamine, dobutamine, or epinephrine can be used for the acute treatment of bradycardia. Temporary pacing is used for treating severe symptomatic bradycardia due to a reversible cause. Permanent cardiac pacing is used for chronic therapy of bradycardia. However, for traditional Chinese medicine (TCM), benefiting qi and nourishing yin and activating blood circulation is the general principle in treatment and show remarkable curative effects. PATIENT CONCERNS: A 32-year-old man was found to have 1-degree atrioventricular block and sinus bradycardia during a physical examination. He reported suffering from palpitation and shortness of breath occasionally. An ambulatory electrocardiogram showed sinus arrhythmia, sinus bradycardia, and significant sinus arrhythmia. The minimum heart rate was 33 bpm (beats per minute). The number of sinus arrest was 42 and the maximum RR interval was 2216 ms. DIAGNOSES: The patient was diagnosed with bradyarrhythmia in Western medicine and "palpitation" in TCM. INTERVENTIONS: The patient was treated with methods of benefiting qi and nourishing yin and activating blood circulation along with warming yan for nearly 5 months. CPM (Chinese patent medicine) such as Yixinshu capsule, Bingdouling oral liquid, Zhenyuan capsule, Zhibaidihuang pills were used for treatment. At the same time, he was suggested to change his lifestyles including falling asleep before 10:00 PM and abandoning spicy diets. OUTCOMES: The symptoms of palpitation and shortness of breath disappeared. The minimum heart rate increased from 33 to 42 bpm and sinus arrests did not occur. The maximum RR interval decreased from 2216 to 1650 ms and the remarkable sinus arrhythmia had improved obviously. LESSONS: This case report shows that TCM can be an effective alternative therapy for sinus bradycardia and cardiac sinus arrests. CPM may have been a successful intervention in arrhythmias.


Assuntos
Bradicardia/tratamento farmacológico , Medicamentos de Ervas Chinesas/uso terapêutico , Medicina Tradicional Chinesa , Parada Sinusal Cardíaca/tratamento farmacológico , Adulto , Humanos , Masculino
11.
Am J Emerg Med ; 37(6): 1217.e1-1217.e2, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30952604

RESUMO

We report here the case of a patient with perindopril intoxication inducing severe bradycardia together with a profound hypotension. Initiation of a naloxone infusion completely resolved those symptoms. As a consequence, we could recommend as a first step the use of naloxone in order to prevent the use of more invasive therapeutic tools.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/envenenamento , Bradicardia/tratamento farmacológico , Hipotensão/tratamento farmacológico , Naloxona/uso terapêutico , Perindopril/envenenamento , Pressão Sanguínea/efeitos dos fármacos , Bradicardia/induzido quimicamente , Humanos , Hipotensão/induzido quimicamente , Masculino , Pessoa de Meia-Idade
13.
J Physiol Sci ; 69(2): 211-222, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30191411

RESUMO

Ivabradine is a selective bradycardic agent that inhibits hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. HCN channels play a key role in mediating the positive chronotropic response to sympathetic nerve stimulation (SNS). We examined whether ivabradine would interfere with dynamic sympathetic control of heart rate (HR). The effect of intravenous ivabradine (2 mg/kg, n = 7) or metoprolol (10 mg/kg, n = 6) on the transfer function from SNS to HR was examined in anesthetized rats. Ivabradine preserved the asymptotic dynamic gain of the HR transfer function and nearly doubled the asymptotic dynamic gain of the transfer function from SNS to the R-R interval. In contrast, metoprolol abolished dynamic sympathetic control of HR. Preserved dynamic sympathetic control of HR, with coexisting bradycardia, may contribute to some of the beneficial effects of ivabradine previously reported in clinical application.


Assuntos
Bradicardia/tratamento farmacológico , Frequência Cardíaca/efeitos dos fármacos , Ivabradina/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Bradicardia/metabolismo , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Masculino , Metoprolol/farmacologia , Ratos , Ratos Endogâmicos WKY , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/metabolismo
14.
Can J Physiol Pharmacol ; 97(2): 90-98, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30462556

RESUMO

Although depression and cardiovascular diseases are related, the role of antidepressants such as fluoxetine (increasing serotonin levels) within cardiac regulation remains unclear. We aimed to determine whether fluoxetine modifies the pharmacological profile of serotonergic influence on vagal cardiac outflow. Rats were treated with fluoxetine (10 mg/kg per day; p.o.) for 14 days or equivalent volumes of drinking water (control group); then, they were pithed and prepared for vagal stimulation. Bradycardic responses were obtained by electrical stimulation of the vagal fibers (3, 6, and 9 Hz) or i.v. acetylcholine (ACh; 1, 5, and 10 µg/kg). The i.v. administration of 5-hydroxytryptamine (5-HT; 10 and 50 µg/kg) inhibited the vagally induced bradycardia. 5-CT (5-HT1/7 agonist) and L-694,247 (5-HT1D agonist) mimicked the serotonin inhibitory effect while α-methyl-5-HT (5-HT2 agonist) was devoid of any action. SB269970 (5-HT7 antagonist) did not abolish 5-CT inhibitory action on the electrically induced bradycardia. Pretreatment with LY310762 (5-HT1D antagonist) blocked the effects induced by L-694,247 and 5-CT. 5-HT and 5-CT failed to modify the bradycardia induced by exogenous ACh. Our outcomes suggest that fluoxetine treatment modifies 5-HT modulation on heart parasympathetic neurotransmission in rats, evoking inhibition of the bradycardia via prejunctional 5-HT1D in pithed rats.


Assuntos
Antidepressivos de Segunda Geração/farmacologia , Bradicardia/tratamento farmacológico , Fluoxetina/farmacologia , Receptor 5-HT1D de Serotonina/metabolismo , Nervo Vago/efeitos dos fármacos , Administração Oral , Animais , Antidepressivos de Segunda Geração/uso terapêutico , Bradicardia/etiologia , Depressão/complicações , Depressão/tratamento farmacológico , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Fluoxetina/uso terapêutico , Coração/inervação , Frequência Cardíaca/efeitos dos fármacos , Humanos , Oxidiazóis/farmacologia , Fenóis/farmacologia , Ratos , Ratos Wistar , Serotonina/farmacologia , Antagonistas do Receptor 5-HT1 de Serotonina/farmacologia , Agonistas do Receptor de Serotonina/metabolismo , Sulfonamidas/farmacologia , Triptaminas/farmacologia , Nervo Vago/metabolismo
15.
Anesth Prog ; 65(3): 192-196, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30235429

RESUMO

Stabilization of circulatory dynamics is a critical issue in the anesthetic management of patients with hypertrophic cardiomyopathy (HCM). In this report, we managed general anesthesia for a 74-year-old male patient with nonobstructive HCM who developed circulatory instability intraoperatively. Severe bradycardia measuring 35 beats/min and hypotension measuring 78 mm Hg systolic were observed during surgery. Using stroke volume variation and stroke volume from the FloTrac as indices, successful circulatory management was performed with dopamine. The hypotension and bradycardia were thought to be the result of methyldigoxin and possibly associated with our perioperative management. Cardiology consult should have been obtained. We demonstrated that the FloTrac can be beneficial in diagnosing and managing cardiovascular instability and administration of dopamine in the anesthetic management of nonobstructive HCM patients.


Assuntos
Anestesia Geral/efeitos adversos , Bradicardia/induzido quimicamente , Cardiomiopatia Hipertrófica/tratamento farmacológico , Cardiotônicos/efeitos adversos , Frequência Cardíaca/efeitos dos fármacos , Medigoxina/efeitos adversos , Procedimentos Cirúrgicos Bucais/efeitos adversos , Idoso , Bradicardia/diagnóstico , Bradicardia/tratamento farmacológico , Bradicardia/fisiopatologia , Cardiomiopatia Hipertrófica/diagnóstico , Cardiomiopatia Hipertrófica/fisiopatologia , Cardiotônicos/administração & dosagem , Dopamina/administração & dosagem , Eletrocardiografia , Humanos , Masculino , Medigoxina/administração & dosagem , Monitorização Intraoperatória/métodos , Fatores de Risco , Resultado do Tratamento
17.
Intern Med J ; 48(7): 868-871, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29984516

RESUMO

Henoch-Schonlein purpura (HSP) is a rare, typically self-limited, multi-organ vasculitis. Cardiac involvement with HSP carries high morbidity and mortality, thus requiring early aggressive immunosuppressive therapy. We report a case of HSP complicated with acute systolic left ventricular (LV) dysfunction, symptomatic sinus bradycardia and high-grade atrio-ventricular (AV) heart block. Cyclophosphamide, a commonly used agent in HSP, was contraindicated due to the patient's presentation with acute renal failure. Treatment with monoclonal antibody rituximab and corticosteroids was initiated with an improvement in and resolution of LV systolic dysfunction, sinus bradycardia and AV block. We believe this is the first published report on rituximab treatment in HSP with cardiac involvement manifesting with severe LV systolic dysfunction, sinus bradycardia and high-grade AV block.


Assuntos
Bradicardia/tratamento farmacológico , Bloqueio Cardíaco/tratamento farmacológico , Púrpura de Schoenlein-Henoch/complicações , Rituximab/administração & dosagem , Disfunção Ventricular Esquerda/tratamento farmacológico , Corticosteroides/uso terapêutico , Eletrocardiografia , Humanos , Imunossupressores/uso terapêutico , Masculino , Pessoa de Meia-Idade , Insuficiência Renal/complicações
18.
Rev Bras Ter Intensiva ; 30(1): 121-126, 2018 Mar.
Artigo em Inglês, Português | MEDLINE | ID: mdl-29742227

RESUMO

Nicotine is a dangerous substance extracted from tobacco leaves. When nicotine is absorbed in excessive amounts, it can lead to respiratory failure and cardiac arrest. The commercialization of electronic cigarettes (e-cigarettes) has allowed users to directly handle e-cigarette liquid. Consequently, the risk of liquid nicotine exposure has increased. We describe our experience of managing the case of a patient who orally ingested a high concentration of liquid nicotine from e-cigarette liquid. The patient presented with bradycardia and hypotension, which are symptoms of parasympathetic stimulation, together with impaired consciousness. He recovered following treatment with atropine and a vasopressor.


Assuntos
Bradicardia/etiologia , Sistemas Eletrônicos de Liberação de Nicotina , Nicotina/envenenamento , Atropina/uso terapêutico , Bradicardia/tratamento farmacológico , Humanos , Hipotensão/tratamento farmacológico , Hipotensão/etiologia , Masculino , Pessoa de Meia-Idade , Vasoconstritores/uso terapêutico
19.
Rev. bras. ter. intensiva ; 30(1): 121-126, jan.-mar. 2018. tab, graf
Artigo em Português | LILACS | ID: biblio-899567

RESUMO

RESUMO A nicotina é uma substância perigosa, extraída das folhas de fumo. Quando absorvida em quantidade excessiva, ela pode levar à insuficiência respiratória e à parada cardíaca. A comercialização de cigarros eletrônicos (e-cigarros) permite que os usuários manuseiem diretamente o líquido, com consequente aumento do risco de exposição à nicotina líquida. Descrevemos nossa experiência no tratamento do caso de um paciente que ingeriu elevada concentração de nicotina líquida contida em líquido para e-cigarros. O paciente apresentava bradicardia e hipotensão, que são sintomas de estimulação parassimpática, além de comprometimento da consciência. O paciente teve recuperação após tratamento com atropina e vasopressor.


ABSTRACT Nicotine is a dangerous substance extracted from tobacco leaves. When nicotine is absorbed in excessive amounts, it can lead to respiratory failure and cardiac arrest. The commercialization of electronic cigarettes (e-cigarettes) has allowed users to directly handle e-cigarette liquid. Consequently, the risk of liquid nicotine exposure has increased. We describe our experience of managing the case of a patient who orally ingested a high concentration of liquid nicotine from e-cigarette liquid. The patient presented with bradycardia and hypotension, which are symptoms of parasympathetic stimulation, together with impaired consciousness. He recovered following treatment with atropine and a vasopressor.


Assuntos
Humanos , Masculino , Bradicardia/etiologia , Sistemas Eletrônicos de Liberação de Nicotina , Nicotina/envenenamento , Atropina/uso terapêutico , Vasoconstritores/uso terapêutico , Bradicardia/tratamento farmacológico , Hipotensão/etiologia , Hipotensão/tratamento farmacológico , Pessoa de Meia-Idade
20.
Sci Rep ; 8(1): 1900, 2018 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-29382866

RESUMO

Stimulation of vagal afferent endings with intravenous phenylbiguanide (PBG) causes both bradycardia and vasodepression, simulating neurally mediated syncope. Activation of µ-opioid receptors in the nucleus tractus solitarius (NTS) increases blood pressure. Electroacupuncture (EA) stimulation of somatosensory nerves underneath acupoints P5-6, ST36-37, LI6-7 or G37-39 selectively but differentially modulates sympathoexcitatory responses. We therefore hypothesized that EA-stimulation at P5-6 or ST36-37, but not LI6-7 or G37-39 acupoints, inhibits the bradycardia and vasodepression through a µ-opioid receptor mechanism in the NTS. We observed that stimulation at acupoints P5-6 and ST36-37 overlying the deep somatosensory nerves and LI6-7 and G37-39 overlying cutaneous nerves differentially evoked NTS neural activity in anesthetized and ventilated animals. Thirty-min of EA-stimulation at P5-6 or ST36-37 reduced the depressor and bradycardia responses to PBG while EA at LI6-7 or G37-39 did not. Congruent with the hemodynamic responses, EA at P5-6 and ST36-37, but not at LI6-7 and G37-39, reduced vagally evoked activity of cardiovascular NTS cells. Finally, opioid receptor blockade in the NTS with naloxone or a specific µ-receptor antagonist reversed P5-6 EA-inhibition of the depressor, bradycardia and vagally evoked NTS activity. These data suggest that point specific EA stimulation inhibits PBG-induced vasodepression and bradycardia responses through a µ-opioid mechanism in the NTS.


Assuntos
Analgésicos Opioides/farmacologia , Bradicardia/tratamento farmacológico , Bradicardia/fisiopatologia , Núcleo Solitário/efeitos dos fármacos , Núcleo Solitário/fisiopatologia , Vasodilatadores/farmacologia , Pontos de Acupuntura , Animais , Pressão Sanguínea/efeitos dos fármacos , Bradicardia/metabolismo , Sistema Cardiovascular/efeitos dos fármacos , Sistema Cardiovascular/metabolismo , Sistema Cardiovascular/fisiopatologia , Gatos , Eletroacupuntura/métodos , Feminino , Frequência Cardíaca/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Masculino , Naloxona/farmacologia , Receptores Opioides/metabolismo , Reflexo/efeitos dos fármacos , Núcleo Solitário/metabolismo , Nervo Vago/efeitos dos fármacos , Nervo Vago/metabolismo , Nervo Vago/fisiopatologia
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