View clinical trials related to Vasoconstriction.
Filter by:Microcirculatory flow is subject to cyclic changes under the influence of heart rate, respiration, myogenic activity, neurogenic factors and endothelial factors. Microcirculatory oscillations (vasomotion) contribute significantly to tissue perfusion. Vasomotion analysis allowed to discriminate normoglycemic subjects, prediabetic subjects and diabetic subjects. Furthermore, changes in vasomotion can precede the emergence of global signs of microangiopathy complications in type 2 diabetes. In fact, few studies reported impaired vasomotion in type 2 diabetes with peripheral neuropathy. Vasomotion analysis after vasodilator (6-min walking test and hyperthermia) and after vasoconstrictor (foot lowering) stimulus could be an effective diagnostic tool to sharpen the diagnostic. Objectives and Methodology: to study vasomotion at baseline and after exercise, hyperthermia and foot lowering within 3 groups of patients: diabetic without peripheral neuropathy, diabetic with subclinical peripheral neuropathy and diabetic with peripheral neuropathy and one group of sex- age- and body mass index-matched healthy control subjects. All the subjects will benefit from a clinical, anthropometric, level of physical activity and biological evaluations. Type 2 diabetes participants will benefit from neuropathy evaluation. In addition, cutaneous microcirculation (perfusion and vasomotion) by means of Laser Doppler Flowmetry and Laser Speckle Imaging will be recorded at rest and after different stimuli (exercise, hyperthermia and foot lowering).
The aim of this double-blind randomized study will be to compare a fixed-rate prophylactic noradrenaline infusion to a fixed-rate prophylactic phenylephrine infusion during elective cesarean section under combined spinal-epidural anesthesia
The objective of this trial is to compare the vasoconstriction potential
Cardiovascular disease (CVD) afflicts nearly one-third of the adult population with all races and ethnicities represented in CVD prevalence. Unfortunately, a disparity exists such that the black population (BL) is disproportionately affected compared to other groups, including the white population (WH). While the underlying cause of this disparity is multifactorial, vascular dysfunction (i.e., impaired vasodilation and/or augmented vasoconstriction) is a key contributor. As has been previously observed, BL exhibit a heightened vasoconstrictor response to both pharmacological (e.g., alpha-adrenergic receptor agonists) and environmental (e.g., cold pressor test) stimuli compared to their WH counterparts. Additionally, reactive oxygen species (ROS) and the subsequent reduction in nitric oxide (NO) bioavailability may partially mediate this response. Our laboratory has recently observed (UTA IRB 2016-0268) that the small blood vessels in the skin (cutaneous microvasculature) in BL, but otherwise healthy individuals, produce an impaired blood flow response to local heating when compared to age-, body mass index (BMI)-, and gender-matched WH. However, pre-treatment of the cutaneous microvasculature with various antioxidants abolishes this skin blood flow difference. These antioxidant drugs inhibit possible sources of ROS, which, as mentioned, maybe mediating the heightened vasoconstrictor response in BL. However, this has not been investigated in this population and thus remains unknown. Therefore, the purpose of this study proposal is to test the following hypotheses: 1) BL will have a greater reduction in cutaneous blood flow in response to local administration of Norepinephrine (alpha1-adrenergic and alpha 2-adrenergic receptor agonist) relative to WH. 2) This greater reduction in the BL population will be related to elevated oxidative stress and subsequent reduction in bioavailability of the potent vasodilator Nitric oxide.
The goal of this study is to examine possible mechanisms of heightened vasoconstriction in Black/African American men and women as possible links to the elevated prevalence of cardiovascular dysfunction and disease. The main targets in this study are sources of oxidative stress
The goal of this study is to examine possible mechanisms of heightened vasoconstriction in Black/African American men and women as possible links to the elevated prevalence of cardiovascular dysfunction and disease. The main targets in this study are sources of oxidative stress.
The goal of the study is to examine the possible mechanisms of impaired cutaneous microvascular function through local heating along with administration of vasoconstrictors.
This study aims to evaluate whether dietary supplementation with fish oil can protect against the cardiopulmonary alterations linked to air pollution
This is the second part of a research study in order to determine if using a specialized pulse oximetry probe with external heat pack will help obtain oxygen saturation (SaO2) and heart rate (HR) during monitoring for patients with peripheral vascular disease (PVD), vasoconstriction, and hypothermic extremities. The inability to obtain accurate SaO2 and pulse readings can lead to misdiagnosis, incorrect treatment, or procedures to be canceled. SaO2 and pulse readings are important to maintain patient stability during diagnostic testing, surgical procedures and monitoring while in critical care areas. Changes in SaO2 and pulse are important to monitor in order to be able to compensate for any decrease in patient oxygen saturations during hemodynamic monitoring. The primary aim of this study is to determine if using a specialized pulse oximetry probe with external heat pack will improve oxygenation readings in order to obtain SaO2 and pulse readings in patients with PVD, vasoconstriction, and hypothermic extremities as compared to readings obtained from an arterial blood gas. The hypothesis is using a specialized pulse oximetry probe with external heat pack will help obtain more accurate pulse oximetry readings consistent with values obtained with an arterial blood gas.
Endothelin-1 (ET-1) has been linked to a number of conditions including pulmonary arterial hypertension (PAH). ET-1 acts via 2 receptors, ETA and ETB. The ET-1 receptor blockers bosentan and sitaxsentan have been shown to be beneficial in patients with PAH. Bosentan blocks both ETA and ETB receptors. Sitaxsentan selectively blocks ETA receptors. Theoretically, selective ETA blockade may be associated with greater vasodilation and clearance of ET-1 by leaving the ETB receptor unblocked. This has not been directly studied in humans. We aim to investigate the endothelial ETB-mediated vascular responses between bosentan and sitaxsentan by using a ETB selective agonist (ET-3). We hypothesise that at clinically relevant doses: - Bosentan will show evidence of ETB receptor blockade compared to sitaxsentan and placebo. - These effects will be confirmed by 2 functional markers of ETB receptor antagonism: plasma ET-1 (a very sensitive, but not necessarily clinically relevant marker), and the forearm vasodilator response to ET-3.