Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28.900
Filtrar
1.
Rev Med Suisse ; 16(692): 907-910, 2020 May 06.
Artigo em Francês | MEDLINE | ID: mdl-32374535

RESUMO

Bladder function is controlled by the autonomic and somatic nervous system in the spinal cord. It is coordinated in the brainstem. Different areas of the brain are involved in the voluntary control of this reflex functioning. Brain lesions often cause an overactive bladder syndrome with increased voiding frequency and urgency. Urinary incontinence, frequently present, may be linked to overactive bladder and associated motor and cognitive disorders. Urinary retention occurs in the acute phase of a hemispherical lesion and following brainstem lesions. The identification, evaluation and treatment of urinary disorders in brain-damaged patients require a global assessment and integrated management taking the other neurological consequences of brain damage into account.


Assuntos
Lesões Encefálicas/complicações , Bexiga Urinária Hiperativa/complicações , Incontinência Urinária/complicações , Lesões Encefálicas/fisiopatologia , Humanos , Reflexo , Bexiga Urinária Hiperativa/fisiopatologia , Incontinência Urinária/fisiopatologia
3.
J Korean Med Sci ; 35(11): e71, 2020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32193902

RESUMO

BACKGROUND: Brain death is a clinical diagnosis that implies irreversible loss of function of the entire brain, including the brainstem and both hemispheres. Based on previous reports, it is not rare for reflex and spontaneous movements to occur in patients during the process of determining brain death. However, reports of the frequency and common types of these movements vary from study to study. Thus, we evaluated adult patients with impending brain death in Korea to determine the frequency and characteristics of reflex and spontaneous movements. METHODS: Brain dead patients who were admitted to 15 hospitals in the Yeongnam region (Southeast) of Korea were recruited prospectively from January 2013 to September 2016. All patients met the criteria for brain death as established by the Korea Medical Association. All body movements occurred during the process of diagnosing brain death and were assessed by physicians and trained organ transplant coordinators. The frequency and characteristics of these movements were identified and the demographic and clinical factors of impending brain dead patients with and without these movements were compared. RESULTS: A total of 436 patients who met the criteria for brain death were enrolled during the study period. Of these patients, 74 (17.0%) exhibited either reflex or spontaneous movements. Of this subset, 45 (60.8%) exhibited reflex movements only, 18 (24.3%) exhibited spontaneous movements only, and 11 (14.9%) exhibited both reflex and spontaneous movements. The most common reflex movements were the flexor/extensor plantar response and spinal myoclonus. Of the 74 patients, 52 (70.3%) exhibited one movement of the same pattern and 22 (29.7%) exhibited two or more different movement patterns. In addition, 45 (60.8%) exhibited these movements only on a limited area of the body with the leg being most common (n = 26, 57.8%). Patients with hypoxic brain damage and a higher systolic blood pressure exhibited significantly more reflex or spontaneous movements. CONCLUSION: Movements associated with brain dead patients are not rare and thus an awareness of these movements is important to brain death diagnosis. Physicians who perform brain death examinations should understand the frequency and characteristics of these movements to reduce delays in determining brain death.


Assuntos
Morte Encefálica/diagnóstico , Movimento , Reflexo , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , República da Coreia
5.
JAMA Neurol ; 77(4): 526, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32119064
6.
Chin J Physiol ; 63(1): 1-6, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32056980

RESUMO

The purpose of this study was to quantitatively assess the difference in sudomotor function between healthy males and females in their early twenties by measuring skin surface area and activated sweat gland density (ASGD). The quantitative sudomotor axon reflex test (QSART), a method for evaluating autonomic nervous system activity, was used for quantification. In QSART, the sweat glands are activated directly or indirectly by the subcutaneous application of neurotransmitters, such as acetylcholine, through iontophoresis. This series of mechanisms is called the sudomotor axon reflex. After recording age, height, weight, and several measurements of the forearm, QSART was performed on 101 healthy controls aged 21-26 years to measure ASGD. The mean temperature and humidity on the measurement days were 11.4°C and 58.1% on May 3, 2018, and 14.7°C and 70.3% on May 10, 2018. The result of independent sample t-test showed higher ASGD in women (P < 0.05). The body surface area and the surface area of the forearms were higher in men (P < 0.001), but the number of activated sweat glands was not significantly different according to sex. The activated sweat gland counts of the body and forearms were analyzed through linear regression by age for males and females. Except for the activated sweat gland count of the male body, the analysis showed a tendency to decrease with increasing age but was not statistically significant in any case (P > 0.05). Showing insufficient coefficient of determination (R2), multiple regression analyses with sex and ages did not correct this insignificance between age and activated sweat gland count.


Assuntos
Glândulas Sudoríparas , Sudorese , Adulto , Axônios , Feminino , Humanos , Iontoforese , Masculino , Reflexo , Adulto Jovem
7.
PLoS One ; 15(2): e0229456, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32101577

RESUMO

Using measures of reflex impairment and injury to quantify an aquatic organism's vitality have gained popularity as survival predictors of discarded non-target fisheries catch. To evaluate the robustness of this method with respect to 'rater' subjectivity, we tested inter- and intra-rater repeatability and the role of 'expectation bias'. From video clips, multiple raters determined impairment levels of four reflexes of beam-trawled common sole (Solea solea) intended for discard. Raters had a range of technical experience, including veterinary students, practicing veterinarians, and fisheries scientists. Expectation bias was evaluated by first assessing a rater's assumption about the effect of air exposure on vitality, then comparing their reflex ratings of the same fish, once when the true air exposure duration was indicated and once when the time was exaggerated (by either 15 or 30 min). Inter-rater repeatability was assessed by having multiple raters evaluate those clips with true air exposure information; and intra- and inter-rater repeatability was determined by having individual raters evaluate a series of duplicated clips, all with true air exposure. Results indicate that inter- and intra-rater repeatability were high (intra-class correlation coefficients of 74% for both), and were not significantly affected by background type nor expectation bias related to assumed impact from prolonged air exposure. This suggests that reflex impairment as a metric for predicting fish survival is robust to involving multiple raters with diverse backgrounds. Bias is potentially more likely to be introduced through subjective reflexes than raters, given that consistency in scoring differed for some reflexes based on rater experience type. This study highlights the need to provide ample training for raters, and that no prior experience is needed to become a reliable rater. Moreover, before implementing reflexes in a vitality study, it is important to evaluate whether the determination of presence/absence is subjective.


Assuntos
Comportamento Animal , Linguados/crescimento & desenvolvimento , Transtornos dos Movimentos/veterinária , Variações Dependentes do Observador , Reflexo/fisiologia , Gravação em Vídeo , Animais , Feminino , Linguados/fisiologia , Humanos , Masculino , Transtornos dos Movimentos/diagnóstico , Reprodutibilidade dos Testes , Inquéritos e Questionários
9.
Am J Physiol Heart Circ Physiol ; 318(4): H916-H924, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32108523

RESUMO

Patients with peripheral artery disease (PAD) have an accentuated exercise pressor reflex (EPR) during exercise of the affected limb. The underlying hemodynamic changes responsible for this, and its effect on blood flow to the exercising extremity, are unclear. We tested the hypothesis that the exaggerated EPR in PAD is mediated by an increase in total peripheral resistance (TPR), which augments redistribution of blood flow to the exercising limb. Twelve patients with PAD and 12 age- and sex-matched subjects without PAD performed dynamic plantar flexion (PF) using the most symptomatic leg at progressive workloads of 2-12 kg (increased by 1 kg/min until onset of fatigue). We measured heart rate, beat-by-beat blood pressure, femoral blood flow velocity (FBV), and muscle oxygen saturation (SmO2) continuously during the exercise. Femoral blood flow (FBF) was calculated from FBV and baseline femoral artery diameter. Stroke volume (SV), cardiac output (CO), and TPR were derived from the blood pressure tracings. Mean arterial blood pressure and TPR were significantly augmented in PAD compared with control during PF. FBF increased during exercise to an equal extent in both groups. However, SmO2 of the exercising limb remained significantly lower in PAD compared with control. We conclude that the exaggerated pressor response in PAD is mediated by an abnormal TPR response, which augments redistribution of blood flow to the exercising extremity, leading to an equal rise in FBF compared with controls. However, this increase in FBF is not sufficient to normalize the SmO2 response during exercise in patients with PAD.NEW & NOTEWORTHY In this study, peripheral artery disease (PAD) patients and healthy control subjects performed graded, dynamic plantar flexion exercise. Data from this study suggest that previously reported exaggerated exercise pressor reflex in patients with PAD is driven by greater vasoconstriction in nonexercising vascular territories which also results in a redistribution of blood flow to the exercising extremity. However, this rise in femoral blood flow does not fully correct the oxygen deficit due to changes in other mechanisms that require further investigation.


Assuntos
Pressão Sanguínea , Exercício Físico , Contração Muscular , Doença Arterial Periférica/fisiopatologia , Reflexo , Idoso , Débito Cardíaco , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Fluxo Sanguíneo Regional
10.
Nat Commun ; 11(1): 326, 2020 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-31949147

RESUMO

Bioinspired electronics are rapidly promoting advances in artificial intelligence. Emerging AI applications, e.g., autopilot and robotics, increasingly spur the development of power devices with new forms. Here, we present a strain-controlled power device that can directly modulate the output power responses to external strain at a rapid speed, as inspired by human reflex. By using the cantilever-structured AlGaN/AlN/GaN-based high electron mobility transistor, the device can control significant output power modulation (2.30-2.72 × 103 W cm-2) with weak mechanical stimuli (0-16 mN) at a gate bias of 1 V. We further demonstrate the acceleration-feedback-controlled power application, and prove that the output power can be effectively adjusted at real-time in response to acceleration changes, i.e., ▵P of 72.78-132.89 W cm-2 at an acceleration of 1-5 G at a supply voltage of 15 V. Looking forward, the device will have great significance in a wide range of AI applications, including autopilot, robotics, and human-machine interfaces.


Assuntos
Inteligência Artificial , Reflexo/fisiologia , Robótica/instrumentação , Robótica/métodos , Transistores Eletrônicos , Compostos de Alumínio/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Elétrons , Gálio/química , Humanos
12.
Nihon Yakurigaku Zasshi ; 155(1): 4-9, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-31902846

RESUMO

The functions of the lower urinary tract, to storage and periodically release urine, are dependent on the activity of smooth and striated muscles in the bladder, urethra and external urethral sphincter. This activity is in turn controlled by neural circuits not only in the periphery, but also in the central nervous system (CNS). During urine storage, the outlet is closed and the bladder smooth muscle is quiescent by the neural control mechanism mainly organized in the spinal cord. When bladder volume reaches the micturition threshold, activation of a micturition center in the dorsolateral pons (the pontine micturition center) induces micturition through activation of sacral parasympathetic (pelvic) nerves. The brain rostral to the pons (diencephalon and cerebral cortex) is also involved in excitatory and inhibitory regulation of the micturition reflex. Various transmitters including dopamine, serotonin, norepenephrine, GABA, excitatory and inhibitory amino acids, opioids and acetylcholine are implicated in the modulation of the micturition reflex in the CNS. Therefore, injury or neurodegenerative diseases of the CNS as well as drugs can produce bladder and urethral dysfunctions such as urinary frequency, urgency and incontinence or inefficient bladder emptying.


Assuntos
Sistema Nervoso Central , Micção , Reflexo , Medula Espinal , Bexiga Urinária
13.
Clin Oral Investig ; 24(2): 883-896, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31236734

RESUMO

OBJECTIVES: The "nociceptive-specific" blink reflex (nBR) evoked by extraoral stimulation has been used to assess trigeminal nociceptive processing in patients with trigeminal nerve damage regardless of the site of damage. This study aimed to test the feasibility of nBR elicited by intraoral stimulation, compare intraoral and extraoral nBR and assess the intrarater and interrater reliability of the intraoral nBR for the maxillary (V2) and mandibular (V3) branches of the trigeminal nerve. MATERIALS AND METHODS: In 17 healthy participants, nBR was elicited by stimulation of two extraoral and two intraoral sites by two operators and repeated intraorally by one operator. Main outcome variables were intraoral stimulus-evoked pain scores and nBR R2 responses at different stimulus intensities. Intraclass correlation coefficients (ICC) were used to assess reliability. RESULTS: Dependent on the stimulus intensity, intraoral stimulation evoked R2 responses in up to 12/17 (70.6%) participants for V2 and up to 8/17 (47.1%) participants for V3. Pain scores (p < 0.003) and R2 responses (p < 0.004) increased with increasing intensities for V2, but not V3. The R2 responses were significantly smaller with intraoral stimulation compared to extraoral stimulation (p < 0.014). Overall, ICCs were fair to excellent for V2 but poor for V3. CONCLUSION: Intraorally evoked nBR was feasible in a subset of healthy participants and was less responsive than nBR with extraoral stimulation. The V2 nBR showed better reliability than V3. CLINICAL RELEVANCE: The nBR can be used to assess nerve damage to the maxillary intraoral regions, though other measures may need to be considered for the mandibular intraoral regions.


Assuntos
Piscadela , Reflexo , Estimulação Elétrica , Estudos de Viabilidade , Humanos , Reprodutibilidade dos Testes
14.
Am J Physiol Heart Circ Physiol ; 318(1): H78-H89, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675256

RESUMO

The role of the acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex is unknown, despite the fact that ASIC1a is opened by decreases in pH in the physiological range. This fact prompted us to test the hypothesis that ASIC1a plays an important role in evoking the exercise pressor reflex in decerebrated rats with freely perfused hindlimb muscles. To test this hypothesis, we measured the effect of injecting two ASIC1a blockers into the arterial supply of the triceps surae muscles on the reflex pressor responses to four maneuvers, namely 1) static contraction of the triceps surae muscles (i.e., the exercise pressor reflex), 2) calcaneal tendon stretch, 3) intra-arterial injection of lactic acid, and 4) intra-arterial injection of diprotonated phosphate. We found that the 2 ASIC1a blockers, psalmotoxin-1 (200 ng/kg) and mambalgin-1 (6.5 µg/kg), decreased the pressor responses to static contraction as well as the peak pressor responses to injection of lactic acid and diprotonated phosphate. In contrast, neither ASIC1a blocker had any effect on the pressor responses to tendon stretch. Importantly, we found that ASIC1a blockade significantly decreased the pressor response to static contraction after a latency of at least 8 s. Our results support the hypothesis that ASIC1a plays a key role in evoking the metabolic component of the exercise pressor reflex.NEW & NOTEWORTHY The role played by acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex remains unknown. In decerebrated rats with freely perfused femoral arteries, blocking ASIC1a with psalmotoxin-1 or mambalgin-1 significantly attenuated the pressor response to static contraction, lactic acid, and diprotonated phosphate injection but had no effect on the pressor response to stretch. We conclude that ASIC1a plays a key role in evoking the exercise pressor reflex by responding to contraction-induced metabolites, such as protons.


Assuntos
Canais Iônicos Sensíveis a Ácido/metabolismo , Sistema Nervoso Autônomo/fisiologia , Células Quimiorreceptoras/metabolismo , Contração Muscular , Fusos Musculares/metabolismo , Músculo Esquelético/inervação , Músculo Esquelético/metabolismo , Reflexo , Canais Iônicos Sensíveis a Ácido/efeitos dos fármacos , Animais , Células Quimiorreceptoras/efeitos dos fármacos , Estado de Descerebração , Venenos Elapídicos/farmacologia , Membro Posterior , Concentração de Íons de Hidrogênio , Masculino , Moduladores de Transporte de Membrana/farmacologia , Fusos Musculares/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Peptídeos/farmacologia , Ratos Sprague-Dawley , Venenos de Aranha/farmacologia
15.
J Oral Rehabil ; 47(3): 386-394, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31698513

RESUMO

OBJECTIVE: To establish how oral bacteria are related to cough sensitivity and pneumonia in a clinical stroke population. BACKGROUND: Stroke patients are at risk of colonisation by respiratory pathogens due, in part, to sudden discontinuation of effective oral hygiene. When combined with reduced cough reflex sensitivity, aspiration of contaminated oropharyngeal contents and can lead to pneumonia. Relationships between oral bacteria, cough sensitivity and pneumonia have not been established. MATERIALS AND METHODS: A total of 102 patients with acute stroke underwent saliva sampling and cough reflex testing at admission to hospital, discharge and one month. A qPCR assay compared levels of bacteria in saliva. Pneumonia events were recorded. RESULTS: Relative levels of bacteria were lowest at admission to hospital (6.04 × 10-6 ). There was a slight (non-significant) increase in bacterial levels at discharge (1.69 × 10-2 , P = .73). By one month, bacterial levels had significantly increased (9.17 × 10-2 ) relative to admission [P < .001] and discharge [P < .001]. Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli are not typically found in healthy mouths, yet were detected in 22% of patients during hospitalisation. Combined bacterial levels measured at one month was associated with pneumonia (P = .004) but there was no relationship to cough sensitivity. CONCLUSION: Acute stroke patients were at increased risk of colonisation from respiratory pathogens throughout their recovery. The presence of these pathogens in saliva at one month was associated with adverse respiratory events. Data support the development of protocols to explore risk factors and sequelae of microbiological changes in stroke.


Assuntos
Transtornos de Deglutição , Pneumonia Aspirativa , Pneumonia , Acidente Vascular Cerebral , Bactérias , Tosse , Humanos , Reflexo
17.
Am J Physiol Heart Circ Physiol ; 318(1): H90-H109, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31702969

RESUMO

Blood flow restriction training (BFRT) is an increasingly widespread method of exercise that involves imposed restriction of blood flow to the exercising muscle. Blood flow restriction is achieved by inflating a pneumatic pressure cuff (or a tourniquet) positioned proximal to the exercising muscle before, and during, the bout of exercise (i.e., ischemic exercise). Low-intensity BFRT with resistance training promotes comparable increases in muscle mass and strength observed during high-intensity exercise without blood flow restriction. BFRT has expanded into the clinical research setting as a potential therapeutic approach to treat functionally impaired individuals, such as the elderly, and patients with orthopedic and cardiovascular disease/conditions. However, questions regarding the safety of BFRT must be fully examined and addressed before the implementation of this exercise methodology in the clinical setting. In this respect, there is a general concern that BFRT may generate abnormal reflex-mediated cardiovascular responses. Indeed, the muscle metaboreflex is an ischemia-induced, sympathoexcitatory pressor reflex originating in skeletal muscle, and the present review synthesizes evidence that BFRT may elicit abnormal cardiovascular responses resulting from increased metaboreflex activation. Importantly, abnormal cardiovascular responses are more clearly evidenced in populations with increased cardiovascular risk (e.g., elderly and individuals with cardiovascular disease). The evidence provided in the present review draws into question the cardiovascular safety of BFRT, which clearly needs to be further investigated in future studies. This information will be paramount for the consideration of BFRT exercise implementation in clinical populations.


Assuntos
Sistema Nervoso Autônomo/fisiologia , Células Quimiorreceptoras/metabolismo , Isquemia , Contração Muscular , Músculo Esquelético/anormalidades , Músculo Esquelético/inervação , Condicionamento Físico Humano/métodos , Reflexo , Oclusão Terapêutica , Adaptação Fisiológica , Animais , Metabolismo Energético , Feminino , Hemodinâmica , Humanos , Masculino , Músculo Esquelético/metabolismo , Condicionamento Físico Humano/efeitos adversos , Fluxo Sanguíneo Regional , Medição de Risco , Oclusão Terapêutica/efeitos adversos
18.
Am J Physiol Regul Integr Comp Physiol ; 318(2): R191-R205, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31664868

RESUMO

This review is based on the Carl Ludwig Distinguished Lecture, presented at the 2019 Experimental Biology Meeting in Orlando, FL, and provides a snapshot of >40 years of work done in collaboration with the late Gerard L. Gebber and colleagues to highlight the importance of considering the rhythmic properties of sympathetic nerve activity (SNA) and brain stem neurons when studying the neural control of autonomic regulation. After first providing some basic information about rhythms, I describe the patterns and potential functions of rhythmic activity recorded from sympathetic nerves under various physiological conditions. I review the evidence that these rhythms reflect the properties of central sympathetic neural networks that include neurons in the caudal medullary raphe, caudal ventrolateral medulla, caudal ventrolateral pons, medullary lateral tegmental field, rostral dorsolateral pons, and rostral ventrolateral medulla. The role of these brain stem areas in mediating steady-state and reflex-induced changes in SNA and blood pressure is discussed. Despite the common appearance of rhythms in SNA, these oscillatory characteristics are often ignored; instead, it is common to simply quantify changes in the amount of SNA to make conclusions about the function of the sympathetic nervous system in mediating responses to a variety of stimuli. This review summarizes work that highlights the need to include an assessment of the changes in the frequency components of SNA in evaluating the cardiovascular responses to various manipulations as well as in determining the role of different brain regions in the neural control of the cardiovascular system.


Assuntos
Tronco Encefálico/fisiologia , Sistema Cardiovascular/inervação , Hemodinâmica , Periodicidade , Reflexo , Sistema Nervoso Simpático/fisiologia , Animais , Humanos , Fatores de Tempo
19.
Am J Physiol Regul Integr Comp Physiol ; 318(1): R30-R37, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31664869

RESUMO

The exercise pressor reflex is composed of two components, namely the muscle mechanoreflex and the muscle metaboreflex. The afferents evoking the two components are either thinly myelinated (group III) or unmyelinated (group IV); in combination they are termed "thin fiber afferents." The exercise pressor reflex is often studied in unanesthetized, decerebrate rats. However, the relationship between the magnitude of this reflex and the number of thin fiber afferents stimulated by muscle contraction is unknown. This lack of knowledge prompted us to test the hypothesis that the magnitude of the exercise pressor reflex was directly proportional to the amount of muscle mass activated. Muscle mechanoreceptors were stimulated by stretching the calcaneal tendon. Likewise, muscle metaboreceptors were stimulated by injecting lactic acid into the arterial supply of the hindlimb muscles. In addition, both muscle mechanoreceptors and metaboreceptors were stimulated by statically contracting the hindlimb muscles. We found that simultaneous bilateral (both hindlimbs) stimulation of thin fiber afferents with stretch, lactic acid, and static contraction evoked significantly greater pressor responses than did unilateral (one hindlimb) stimulation of these afferents. In addition, the magnitude of the pressor responses to bilateral simultaneous stimulation of thin fiber afferents evoked by stretch, lactic acid, and contraction was not significantly different from the magnitude of the sum of the pressor responses evoked by unilateral stimulation of these afferents by stretch, lactic acid, and contraction. We conclude that the magnitude of the exercise pressor reflex and its two components is dependent on the number of afferents stimulated.


Assuntos
Pressão Sanguínea/fisiologia , Estado de Descerebração , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Reflexo/fisiologia , Animais , Membro Posterior , Masculino , Ratos , Ratos Sprague-Dawley
20.
Am J Physiol Regul Integr Comp Physiol ; 318(2): R311-R319, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31823673

RESUMO

Patients with type 2 diabetes (T2D) exhibit greater daytime blood pressure (BP) variability, increasing their cardiovascular risk. Given the number of daily activities that incorporate short-duration isometric muscle contractions (e.g., carrying groceries), herein we investigated BP and muscle sympathetic nerve activity (MSNA) responses at the onset of isometric handgrip (HG). We tested the hypothesis that, relative to control subjects, patients with T2D would exhibit exaggerated pressor and MSNA responses to the immediate onset of HG. Mean arterial pressure (MAP) and MSNA were quantified during the first 30 s of isometric HG at 30% and 40% of maximal voluntary contraction (MVC) and during a cold pressor test (CPT), a nonexercise sympathoexcitatory stimulus. The onset of 30% MVC HG evoked similar increases in MAP between groups (P = 0.17); however, the increase in MSNA was significantly greater in patients with T2D versus control subjects with the largest group difference at 20 s (P < 0.001). At the onset of 40% MVC HG, patients with T2D demonstrated greater increases in MAP (e.g., 10 s, T2D: 9 ± 1 mmHg, controls: 5 ± 2 mmHg; P = 0.04). MSNA was also greater in patients with T2D at 40% MVC onset but differences were only significant at the 20-30 s timepoint (T2D: 15 ± 3 bursts/min, controls: -2 ± 4 bursts/min; P < 0.001). Similarly, MAP and MSNA responses were augmented during the onset of CPT in T2D patients. These findings demonstrate exaggerated pressor and MSNA reactivity in patients with T2D, with rapid and robust responses to both isometric contractions and cold stress. This hyper-responsiveness may contribute to daily surges in BP in patients with T2D, increasing their short-term and long-term cardiovascular risk.


Assuntos
Pressão Arterial , Diabetes Mellitus Tipo 2/fisiopatologia , Contração Isométrica , Músculo Esquelético/inervação , Reflexo , Sistema Nervoso Simpático/fisiopatologia , Biomarcadores/sangue , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Feminino , Hemoglobina A Glicada/metabolismo , Humanos , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Missouri , Estudos Retrospectivos , Texas , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA