RESUMO
BACKGROUND: Migraine prevalence and levels of calcitonin gene-related peptide (CGRP), a peptide involved in migraine pathophysiology, differ between men and women, and appear to be affected by changes in sex hormones. The present study investigated the sex-specific responses to CGRP in human isolated arteries. METHODS: CGRP-induced relaxation of 62 (28 men and 34 women) human isolated middle meningeal arteries (HMMA) and 139 (69 men and 70 women) human isolated coronary arteries (HCA) was compared between men and women in groups <50 years and ≥50 years of age as a proxy for pre- and postmenopausal status in women, as well as matched-age groups for men. RESULTS: In HCA, no differences were observed between male and female tissue, or between the different age groups. However, in HMMA, the maximum response was significantly smaller and CGRP was less potent in females <50 compared with males <50 years of age. No differences were observed between the older age groups. CONCLUSIONS: Sex differences were observed for CGRP-induced relaxation of HMMA, but not HCA. These differences could arise from differential receptor expression in the vascular beds combined with the effect of sex hormones on CGRP and subsequent receptor desensitization.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina , Vasos Coronários , Artérias Meníngeas , Transtornos de Enxaqueca , Caracteres Sexuais , Vasodilatação , Humanos , Feminino , Masculino , Pessoa de Meia-Idade , Peptídeo Relacionado com Gene de Calcitonina/farmacologia , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Transtornos de Enxaqueca/fisiopatologia , Transtornos de Enxaqueca/metabolismo , Artérias Meníngeas/efeitos dos fármacos , Artérias Meníngeas/fisiologia , Vasodilatação/fisiologia , Vasodilatação/efeitos dos fármacos , Adulto , Vasos Coronários/efeitos dos fármacos , IdosoRESUMO
Arterial smooth muscle exhibits rhythmic oscillatory contractions called vasomotion and believed to be a protective mechanism against tissue hypoperfusion or hypoxia. Oscillations of vascular tone depend on voltage and follow oscillations of the membrane potential. Voltage-gated sodium channels (Nav), responsible for the initiation and propagation of action potentials in excitable cells, have also been evidenced both in animal and human vascular smooth muscle cells (SMCs). For example, they contribute to arterial contraction in rats, but their physiopathological relevance has not been established in human vessels. In the present study, we investigated the functional role of Nav in the human artery. Experiments were performed on human uterine arteries obtained after hysterectomy and on SMCs dissociated from these arteries. In SMCs, we recorded a tetrodotoxin (TTX)-sensitive and fast inactivating voltage-dependent INa current. Various Nav genes, encoding α-subunit isoforms sensitive (Nav 1.2; 1.3; 1.7) and resistant (Nav 1.5) to TTX, were detected both in arterial tissue and in SMCs. Nav channels immunostaining showed uniform distribution in SMCs and endothelial cells. On arterial tissue, we recorded variations of isometric tension, ex vivo, in response to various agonists and antagonists. In arterial rings placed under hypoxic conditions, the depolarizing agent KCl and veratridine, a specific Nav channels agonist, both induced a sustained contraction overlaid with rhythmic oscillations of tension. After suppression of sympathetic control either by blocking the release of catecholamine or by antagonizing the target adrenergic response, rhythmic activity persisted while the sustained contraction was abolished. This rhythmic activity of the arteries was suppressed by TTX but, in contrast, only attenuated by antagonists of calcium channels, Na+/Ca2+ exchanger, Na+/K+-ATPase and the cardiac Nav channel. These results highlight the role of Nav as a novel key element in the vasomotion of human arteries. Hypoxia promotes activation of Nav channels involved in the initiation of rhythmic oscillatory contractile activity.
Assuntos
Artérias/metabolismo , Hipóxia/metabolismo , Contração Muscular/fisiologia , Canais de Sódio Disparados por Voltagem/metabolismo , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Adulto , Animais , Artérias/efeitos dos fármacos , Canais de Cálcio/metabolismo , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Feminino , Humanos , Pessoa de Meia-Idade , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Trocador de Sódio e Cálcio/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Tetrodotoxina/farmacologiaRESUMO
Background: Digital image correlation (DIC) methods are increasingly used for non-contact optical assessment of geometry and deformation in soft tissue biomechanics, thus providing the full-field strain estimates needed for robust inverse material characterization. Despite the well-known flexibility and ease of use of DIC, issues related to spatial resolution and depth-of-field remain challenging in studies of quasi-cylindrical biological samples such as arteries. Objective: After demonstrating that standard surrounding multi-view DIC systems are inappropriate for such usage, we submit that both the optical setup and the data analysis need to be specifically designed with respect to the size of the arterial sample of interest. Accordingly, we propose novel and optimized DIC systems for two distinct ranges of arterial diameters: less than 2.5 mm (murine arteries) and greater than 10 mm (human arteries). Methods: We designed, set up, and validated a four-camera panoramic-DIC system for testing murine arteries and a multi-biprism DIC system for testing human arteries. Both systems enable dynamic 360-deg measurements with refraction correction over the entire surface of submerged samples in their native geometries. Results: Illustrative results for 3D shape and full-surface deformation fields were obtained for a mouse infrarenal aorta and a latex cylinder of size similar to the human infrarenal aorta. Conclusion: Results demonstrated the feasibility and accuracy of both proposed methods in providing quantitative information on the regional behavior of arterial samples tested in vitro under physiologically relevant loading.
RESUMO
In the rodent cerebral circulation, inward rectifying K+ (KIR) channels set resting tone and the distance over which electrical phenomena spread along the arterial wall. The present study sought to translate these observations into human cerebral arteries obtained from resected brain tissue. Computational modeling and a conduction assay first defined the impact of KIR channels on electrical communication; patch-clamp electrophysiology, quantitative PCR, and immunohistochemistry then characterized KIR2.x channel expression/activity. In keeping with rodent observations, computer modeling highlighted that KIR blockade should constrict cerebral arteries and attenuate electrical communication if functionally expressed. Surprisingly, Ba2+ (a KIR channel inhibitor) had no effect on human cerebral arterial tone or intercellular conduction. In alignment with these observations, immunohistochemistry and patch-clamp electrophysiology revealed minimal KIR channel expression/activity in both smooth muscle and endothelial cells. This absence may be reflective of chronic stress as dysphormic neurons, leukocyte infiltrate, and glial fibrillary acidic protein expression was notable in the epileptic cortex. In closing, KIR2.x channel expression is limited in human cerebral arteries from patients with epilepsy and thus has little impact on resting tone or the spread of vasomotor responses. NEW & NOTEWORTHY KIR2.x channels are expressed in rodent cerebral arterial smooth muscle and endothelial cells. As they are critical to setting membrane potential and the distance signals conduct, we sought to translate this work into humans. Surprisingly, KIR2.x channel activity/expression was limited in human cerebral arteries, a paucity tied to chronic brain stress in the epileptic cortex. Without substantive expression, KIR2.x channels were unable to govern arterial tone or conduction.
Assuntos
Artérias Cerebrais/fisiologia , Canais de Potássio Corretores do Fluxo de Internalização/fisiologia , Adulto , Bário/farmacologia , Comunicação Celular , Artérias Cerebrais/efeitos dos fármacos , Simulação por Computador , Fenômenos Eletrofisiológicos/fisiologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/fisiologia , Epilepsia/fisiopatologia , Feminino , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Tono Muscular/efeitos dos fármacos , Músculo Liso Vascular/citologia , Miócitos de Músculo Liso/metabolismo , Técnicas de Patch-Clamp , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio Corretores do Fluxo de Internalização/efeitos dos fármacos , Adulto JovemRESUMO
Homocysteine (Hcy) is an independent risk factor for endothelial dysfunction in cardiovascular diseases. We hypothesized that the eNOS transcription enhancer AVE3085 may protect the endothelial function damaged by Hcy in the human internal mammary artery (IMA). Cumulative concentration-relaxation curves to acetylcholine (-10 to -4.5 log mol/L) or sodium nitroprusside were established in IMA from patients undergoing coronary artery surgery precontracted by U46619 (-8 log mol/L) in the absence/presence of Hcy (100⯵mol/L) with/without AVE3085 (30⯵mol/L) in vitro in a myograph. RT-qPCR and ELISA were used to quantify the mRNA and protein levels of eNOS. Colorimetric assay method was used to detect the production of nitric oxide (NO). Maximal relaxation was significantly attenuated by Hcy in human IMA. Co-incubation with AVE3085 protected endothelium from the impairment by Hcy and increased the production of NO. Exposure to Hcy for 24â¯h downregulated eNOS protein expression (Pâ¯<â¯0.05) whereas it upregulated the expression of eNOS at mRNA levels (Pâ¯<â¯0.05). The presence of AVE3085 in addition to Hcy significantly increased the eNOS protein (Pâ¯<â¯0.05) and slightly decreased the mRNA level. The study for the first time revealed that in the human blood vessels (IMA) the clinically-relevant high concentration of Hcy directly causes endothelial dysfunction by downregulating eNOS protein that may be reversed by AVE3085. These findings not only provide new direction for protecting endothelium during coronary artery bypass grafting and improving long-term patency of the grafts, but also provide evidence to the use of eNOS enhancer in the patients with endothelial dysfunction in various pathological conditions.
Assuntos
Benzodioxóis/farmacologia , Endotélio Vascular/fisiopatologia , Homocisteína/metabolismo , Indanos/farmacologia , Artéria Torácica Interna/efeitos dos fármacos , Óxido Nítrico Sintase Tipo III/metabolismo , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacologia , Acetilcolina/farmacologia , Acetilcisteína/farmacologia , Endotélio Vascular/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Homocisteína/farmacologia , Humanos , Artéria Torácica Interna/fisiopatologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/genética , Nitroprussiato/farmacologia , Técnicas de Cultura de Órgãos , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
Reported here are the results of an experimental study on the response to low-intensity cavitation induced by low-frequency (4-6 W/cm2, 20 kHz and 32.6 kHz) ultrasound of isolated human arterial samples taken during conventional myocardial revascularization operations. Studies have found that low-frequency ultrasound results in a significant (48%-54%) increase in isometric contraction force and does not depend on the number of exposures (10 or 20) or the time passed since the start of ultrasound (0, 10 and 20 min), but does depend on the frequency and location (internal or external) of the blood vessels for the application of ultrasound. Diltiazem (an inhibitor of slow calcium channels) and carbachol (an agonist of muscarinic receptors) used in a concentration-dependent manner did not modify the relaxation dynamics of smooth muscle affected by ultrasound. Thus, ultrasound conditioned to the augmentation of the isometric contraction force the smooth muscle of blood vessels and did not improve endothelial- and calcium channel blocker-dependent relaxation.
Assuntos
Contração Isométrica/fisiologia , Revascularização Miocárdica , Artérias Torácicas/fisiologia , Ondas Ultrassônicas , Idoso , Feminino , Humanos , Técnicas In Vitro , MasculinoRESUMO
AIM: Calcium channel blockers are widely used in cardiovascular diseases. Besides L-type channels, T- and P/Q-type calcium channels are involved in the contraction of human renal blood vessels. It was hypothesized that T- and P/Q-type channels are involved in the contraction of human brain and mammary blood vessels. METHODS: Internal mammary arteries from bypass surgery patients and cerebral arterioles from patients with brain tumours with and without hypertension were tested in a myograph and perfusion set-up. PCR and immunohistochemistry were performed on isolated blood vessels. RESULTS: The P/Q-type antagonist ω-agatoxin IVA (10-8 mol L-1 ) and the T-type calcium blocker mibefradil (10-7 mol L-1 ) inhibited KCl depolarization-induced contraction in mammary arteries from hypertensive patients with no effect on blood vessels from normotensive patients. ω-Agatoxin IVA decreased contraction in cerebral arterioles from hypertensive patients. L-type blocker nifedipine abolished the contraction in mammary arteries. PCR analysis showed expression of P/Q-type (Cav 2.1), T-type (Cav 3.1 and Cav 3.2) and L-type (Cav 1.2) calcium channels in mammary and cerebral arteries. Immunohistochemical labelling of mammary and cerebral arteries revealed the presence of Cav 2.1 in endothelial and smooth muscle cells. Cav 3.1 was also detected in mammary arteries. CONCLUSION: P/Q- and T-type Cav are present in human internal mammary arteries and in cerebral penetrating arterioles. P/Q- and T-type calcium channels are involved in the contraction of mammary arteries from hypertensive patients but not from normotensive patients. Furthermore, in cerebral arterioles P/Q-type channels importance was restricted to hypertensive patients might lead to that T- and P/Q-type channels could be a new target in hypertensive patients.
Assuntos
Canais de Cálcio/metabolismo , Artérias Cerebrais/metabolismo , Hipertensão/metabolismo , Artéria Torácica Interna/metabolismo , Vasoconstrição/fisiologia , Idoso , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/efeitos dos fármacos , Artérias Cerebrais/efeitos dos fármacos , Feminino , Humanos , Imuno-Histoquímica , Masculino , Artéria Torácica Interna/efeitos dos fármacos , Pessoa de Meia-Idade , Técnicas de Cultura de Órgãos , Técnicas de Patch-Clamp , Reação em Cadeia da Polimerase , Vasoconstrição/efeitos dos fármacosRESUMO
BACKGROUND: Arteries undergo large deformations under applied intraluminal pressure and may exhibit small hysteresis due to creep or relaxation process. The mechanical response of arteries depends, among others, on their topology along the arterial tree. Viscoelasticity of arterial tissues, which is the topic investigated in this study, is mainly a characteristic mechanical response of arteries that are located away from the heart and have increased smooth muscle cells content. METHODS: The arterial wall viscosity is simulated by adopting a generalized Maxwell model and the method of internal variables, as proposed by Bonet and Holzapfel et al. The total stresses consist of elastic long-term stresses and viscoelastic stresses, requiring an iterative procedure for their calculation. The cross-section of the artery is modeled as a circular ring, consisting of a single homogenized layer, under a time-varying blood pressure. Two different loading approximations for the aortic pressure vs time are considered. A novel numerical method is developed in order to solve the controlling integro-differential equation. RESULTS: A large number of numerical investigations are performed and typical response time-profiles are presented in pictorial form. Results suggest that the viscoelastic arterial response is mainly affected by the ratio of the relaxation time to the characteristic time of the response and by the pressure-time approximation. Numerical examples, based on data available in the literature, are conducted. CONCLUSIONS: The investigation presented in this study reveals the effect of each material parameter on the viscoelastic arterial response. Thus, a better understanding of the behavior of viscoelastic arteries is achieved.