removing the microdialysis probes after performing the dose-response experiments

Étude de nouveaux mécanismes de dysfonctionnement microvasculaire chez l’homme

Cardiovascular disease (CVD) is the leading cause of death in the United States1. Hypertension (HTN) is an independent risk factor for stroke, coronary heart disease, and heart failure and is estimated to affect upward of ~50% of the United States population2. HTN can develop as an independent CVD (primary HTN) or as a result of another condition, such as polycystic kidney disease and/or endocrine disorders (secondary HTN). The breadth of etiologies of HTN complicates investigations into the underlying mechanisms and end-organ damage observed with HTN. Diverse and novel research approaches into the pathophysiology of the end-organ damage associated with HTN are needed.
One of the earliest pathological signs of CVD is endothelial dysfunction, as characterized by impaired nitric oxide (NO)-mediated vasodilation3,4,5. Flow-mediated dilation is a common approach used to quantify the endothelial dysfunction associated with CVD, but endothelial dysfunction in microvascular beds can be both independent of and precursory to that of large conduit arteries6,7,8. Furthermore, resistance arterioles are more directly acted on by local tissue than conduit arteries and have more immediate control over the delivery of oxygen-rich blood. Microvascular function is predictive of adverse cardiovascular event-free survival9,10,11. The cutaneous microvasculature is an accessible vascular bed that can be used to examine responses to physiological and pharmacological vasoconstrictive or vasodilatory stimuli. Intradermal microdialysis is a minimally invasive technique, the goal of which is to investigate the mechanisms of both vascular smooth muscle and endothelial function in the cutaneous microvasculature with targeted pharmacological dissection. This method contrasts with other techniques, such as post-occlusive reactive hyperemia, which does not allow for pharmacological dissection, and iontophoresis, which allows for pharmacological delivery but is less precise in its mechanism of action (reviewed thoroughly elsewhere12).
The rationale behind the development and use of this technique is extensively reviewed elsewhere13. This approach was originally developed for use in neurological research in rodents and then was first applied to humans to investigate the mechanisms underlying active vasodilation from a thermoregulatory standpoint. In the late 1990s, this method was used to examine both neural and endothelial mechanisms with regard to local heating of the skin. Since that time, the technique has been utilized to investigate a number of neurovascular signaling mechanisms in the skin.
Using this technique, our group and others have interrogated the mechanisms of endothelial dysfunction in the microvasculature of several clinical populations, including, but not limited to, dyslipidemia, primary aging, diabetes, chronic kidney disease, polycystic ovary syndrome, preeclampsia, major depressive disorder14,15,16,17,18,19, and hypertension20,21,22,23,24. For example, a previous study found that normotensive women with a history of preeclampsia, who are at an increased risk for CVD, had reduced NO-mediated vasodilation in the cutaneous circulation compared with women with a history of normotensive pregnancy20. In another study, adults diagnosed with primary HTN demonstrated increased angiotensin II sensitivity in the microvasculature compared with healthy controls21, and chronic sulfhydryl-donating antihypertensive pharmacotherapy in primary HTN patients has been shown to decrease blood pressure and improve both hydrogen sulfide- and NO-mediated vasodilation22. Wong et al.23 found impaired sensory-mediated and NO-mediated vasodilation in prehypertensive adults, coinciding with our finding of a progression of endothelial dysfunction with increasing HTN stages, as categorized by the 2017 American Heart Association and American College of Cardiology guidelines24.
The intradermal microdialysis technique allows for tightly controlled mechanistic investigations into microvascular function in health and disease states. Therefore, this paper aims to describe the intradermal microdialysis technique as applied by our group and others. We detail the procedures for both pharmacological stimulation of the endothelium with acetylcholine (ACh) to examine the dose-response relationship and physiological stimulation of endogenous NO production with either a 39 &#176;C or 42 &#176;C local heating stimulus protocol. We present representative results for each approach and discuss the clinical implications of the findings that have arisen from this technique.

Pleins feux sur l’auteur : Une approche de pharmacodissection pour découvrir les mécanismes dans les populations à risque de maladies cardiovasculaires 

Microdialyse intradermique : une approche pour étudier les nouveaux mécanismes du dysfonctionnement microvasculaire chez l’homme

Watch this Scientific Journal Video about Removing the Microdialysis Probes After Performing the Dose-Response Experiments at JoVE.com

Removing the Microdialysis Probes After Performing the Dose-Response Experiments  

Retrait des sondes de microdialyse après avoir effectué les expériences dose-réponse

Après avoir effectué l’expérience dose-réponse, utilisez des ciseaux chirurgicaux pour couper les sondes de microdialyse. Retirez délicatement les sondes de débitmétrie laser Doppler des appareils de chauffage et détachez les éléments chauffants de la peau. Retirez délicatement le ruban adhésif fixant les sondes à la peau.Inspectez les sites de ponction de chaque côté de la sonde pour identifier le plus petit caillot sanguin. Coupez la sonde près du site avec le plus petit caillot, en laissant environ un pouce de la sonde à l’extérieur de la peau non coupée. Nettoyez ensuite la zone cutanée autour des sites d’entrée et de sortie de la sonde à l’aide d’un tampon imbibé d’alcool, y compris la longueur d’un pouce du côté le moins coagulé.Saisissez la sonde qui s’étend du site de ponction avec le plus gros caillot et tirez-la doucement vers le caillot. Enfin, couvrez tout saignement dû au retrait de la sonde avec de la gaze stérile et appliquez une pression.

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Removing the Microdialysis Probes After Performing the Dose-Response Experiments

92 vues. Après avoir effectué l’expérience dose-réponse, utilisez des ciseaux chirurgicaux pour couper les sondes de microdialyse. Retirez délicatement les sondes de débitmétrie laser Doppler des appareils de chauffage et détachez les éléments chauffants de la peau. Retirez délicatement le ruban adhésif fixant les sondes à la peau.Inspectez les sites de ponction de chaque côté de la sonde pour identifier le plus petit caillot sanguin. Coupez la sonde près du site avec le plus ...

Vidéo: Removing the Microdialysis Probes After Performing the Dose-Response Experiments  

Intradermal Microdialysis: An Approach to Investigating Novel Mechanisms of Microvascular Dysfunction in Humans

The cutaneous vasculature is an accessible tissue that can be used to assess microvascular function in humans. Intradermal microdialysis is a minimally invasive technique used to investigate mechanisms of vascular smooth muscle and endothelial function in the cutaneous circulation. This technique allows for the pharmacological dissection of the pathophysiology of microvascular endothelial dysfunction as indexed by decreased nitric oxide-mediated vasodilation, an indicator of cardiovascular disease development risk. In this technique, a microdialysis probe is placed in the dermal layer of the skin, and a local heating unit with a laser Doppler flowmetry probe is placed over the probe to measure the red blood cell flux. The local skin temperature is clamped or stimulated with direct heat application, and pharmacological agents are perfused through the probe to stimulate or inhibit intracellular signaling pathways in order to induce vasodilation or vasoconstriction or to interrogate mechanisms of interest (co-factors, antioxidants, etc.). The cutaneous vascular conductance is quantified, and mechanisms of endothelial dysfunction in disease states can be delineated.

Intradermal microdialysis is a minimally invasive technique used to investigate microvascular function in health and disease. Both dose-response and local heating protocols can be utilized for this technique to explore mechanisms of vasodilation and vasoconstriction in the cutaneous circulation.

The cutaneous vasculature is an accessible tissue that can be used to assess microvascular function in humans. Intradermal microdialysis is a minimally ...