Methods and Applications in Vascular Physiology: 2021

Editorial

08 November 2022

Editorial: Methods and applications in vascular physiology: 2021

Julien V. Brugniaux

Rosalia Rodriguez-Rodriguez

Ali Dabiri

Kıvılcım Kılıç

, 2 more and

Antonio Colantuoni

1,302 views

0 citations

Editors

Ali Dabiri

California Medical Innovations Institute

Julien Vincent Brugniaux

Université Grenoble Alpes

Alexey Goltsov

Moscow State Institute of Radio Engineering, Electronics and Automation

Kıvılcım Kılıç

Boston University

Antonio Colantuoni

University of Naples Federico II

Rosalia Rodriguez-Rodriguez

International University of Catalonia

Calum Wilson

University of Strathclyde

Impact

Methods

22 August 2022

Application of a multicomponent model of convectional reaction-diffusion to description of glucose gradients in a neurovascular unit

Yaroslav R. Nartsissov

A supply of glucose to a nervous tissue is fulfilled by a cerebrovascular network, and further diffusion is known to occur at both an arteriolar and a microvascular level. Despite a direct relation, a blood flow dynamic and reaction-diffusion of metabolites are usually considered separately in the mathematical models. In the present study they are coupled in a multiphysical approach which allows to evaluate the effects of capillary blood flow changes on near-vessels nutrient concentration gradients evidently. Cerebral blood flow (CBF) was described by the non-steady-state Navier-Stokes equations for a non-Newtonian fluid whose constitutive law is given by the Carreau model. A three-level organization of blood–brain barrier (BBB) is modelled by the flux dysconnectivity functions including densities and kinetic properties of glucose transporters. The velocity of a fluid flow in brain extracellular space (ECS) was estimated using Darcy’s law. The equations of reaction-diffusion with convection based on a generated flow field for continues and porous media were used to describe spatial-time gradients of glucose in the capillary lumen and brain parenchyma of a neurovascular unit (NVU), respectively. Changes in CBF were directly simulated using smoothing step-like functions altering the difference of intracapillary pressure in time. The changes of CBF cover both the decrease (on 70%) and the increase (on 50%) in a capillary flow velocity. Analyzing the dynamics of glucose gradients, it was shown that a rapid decrease of a capillary blood flow yields an enhanced level of glucose in a near-capillary nervous tissue if the contacts between astrocytes end-feet are not tight. Under the increased CBF velocities the amplitude of glucose concentration gradients is always enhanced. The introduced approach can be used for estimation of blood flow changes influence not only on glucose but also on other nutrients concentration gradients and for the modelling of distributions of their concentrations near blood vessels in other tissues as well.

1,548 views

10 citations

Original Research

25 March 2022

Carotid Reservoir Pressure Decrease After Prolonged Head Down Tilt Bed Rest in Young Healthy Subjects Is Associated With Reduction in Left Ventricular Ejection Time and Diastolic Length

Carlo Palombo

, 6 more and

Alun D. Hughes

1,933 views

2 citations

Correction

17 August 2022

Corrigendum: Carotid reservoir pressure decrease after prolonged head down tilt bed rest in young healthy subjects is associated with reduction in left ventricular ejection time and diastolic length

Carlo Palombo

, 6 more and

Alun D. Hughes

1,840 views

0 citations

(A) During the first pacing session, prior to administration of vehicle or phenylephrine, blood pressure was decreased with increasing pacing frequencies in both groups (****P < 0.0001 for systolic pressure and ++P = 0.0028). (B) During the second pacing session after administration of phenylephrine, blood pressure did not change with increasing pacing frequencies, but elevation of blood pressure compared to vehicle group was maintained (*P = 0.028 for systolic blood pressure and ++P = 0.0064 for diastolic pressure). (C) Stroke volume decreased significantly with increasing pacing frequencies (****P < 0.0001). (D) Cardiac output was also affected with increasing pacing frequencies (***P = 0.0002). (E) Total peripheral resistance did not change with increasing pacing frequencies, but the phenylephrine-induced increments in total peripheral resistance were maintained during the second pacing session compared to the vehicle group (*P = 0.04). Data were compared with two-way ANOVA, n = 6.

Methods

17 February 2022

Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate

Rajkumar Rajanathan

, 3 more and

Vladimir V. Matchkov

Objective: Investigating the cardiovascular system is challenging due to its complex regulation by humoral and neuronal factors. Despite this complexity, many existing research methods are limited to the assessment of a few parameters leading to an incomplete characterization of cardiovascular function. Thus, we aim to establish a murine in vivo model for integrated assessment of the cardiovascular system under conditions of controlled heart rate. Utilizing this model, we assessed blood pressure, cardiac output, stroke volume, total peripheral resistance, and electrocardiogram (ECG).

Hypothesis: We hypothesize that (i) our in vivo model can be utilized to investigate cardiac and vascular responses to pharmacological intervention with the α₁-agonist phenylephrine, and (ii) we can study cardiovascular function during artificial pacing of the heart, modulating cardiac function without a direct vascular effect.

Methods: We included 12 mice that were randomly assigned to either vehicle or phenylephrine intervention through intraperitoneal administration. Mice were anesthetized with isoflurane and intubated endotracheally for mechanical ventilation. We measured blood pressure via a solid-state catheter in the aortic arch, blood flow via a probe on the ascending aorta, and ECG from needle electrodes on the extremities. Right atrium was electrically paced at a frequency ranging from 10 to 11.3 Hz before and after either vehicle or phenylephrine administration.

Results: Phenylephrine significantly increased blood pressure, stroke volume, and total peripheral resistance compared to the vehicle group. Moreover, heart rate was significantly decreased following phenylephrine administration. Pacing significantly decreased stroke volume and cardiac output both prior to and after drug administration. However, phenylephrine-induced changes in blood pressure and total peripheral resistance were maintained with increasing pacing frequencies compared to the vehicle group. Total peripheral resistance was not significantly altered with increasing pacing frequencies suggesting that the effect of phenylephrine is primarily of vascular origin.

Conclusion: In conclusion, this in vivo murine model is capable of distinguishing between changes in peripheral vascular and cardiac functions. This study underlines the primary effect of phenylephrine on vascular function with secondary changes to cardiac function. Hence, this in vivo model is useful for the integrated assessment of the cardiovascular system.

5,420 views

7 citations