Localized Oxygen Exchange Platform for Intravital Video Microscopy Investigations of Microvascular Oxygen Regulation.

Richard J Sové,Stephanie Milkovich,Hristo N Nikolov,Graham M Fraser,David W Holdsworth,Christopher G Ellis

doi:10.3389/fphys.2021.654928

Abstract

Intravital microscopy has proven to be a powerful tool for studying microvascular physiology. In this study, we propose a gas exchange system compatible with intravital microscopy that can be used to impose gas perturbations to small localized regions in skeletal muscles or other tissues that can be imaged using conventional inverted microscopes. We demonstrated the effectiveness of this system by locally manipulating oxygen concentrations in rat extensor digitorum longus muscle and measuring the resulting vascular responses. A computational model of oxygen transport was used to partially validate the localization of oxygen changes in the tissue, and oxygen saturation of red blood cells flowing through capillaries were measured as a surrogate for local tissue oxygenation. Overall, we have demonstrated that this approach can be used to study dynamic and spatial responses to local oxygen challenges to the microenvironment of skeletal muscle.

Highlights

Oxygen (O2) regulation is a critical physiological function where precise regulatory control is required to ensure the metabolic demands of the tissues of the body are met (Duling, 1972; Sparks, 1980; Kontos and Wei, 1985; Golub and Pittman, 2013)
We developed a modular gas exchange platform to deliver a localized gas composition to the surface of externalized extensor digitorum longus (EDL) muscle tissue for use in intravital microscopy studies
Our model predicts that the platform is able to change red blood cell (RBC) SO2 in capillaries within a localized area of approximately 614 by 434 μm (Figure 5)

Summary

Introduction

Oxygen (O2) regulation is a critical physiological function where precise regulatory control is required to ensure the metabolic demands of the tissues of the body are met (Duling, 1972; Sparks, 1980; Kontos and Wei, 1985; Golub and Pittman, 2013). Numerous studies have confirmed that the presence or absence of O2 in the microcirculation results in a vasoactive response such that high levels of O2 result in vasoconstriction (Duling, 1972; Hutchins et al, 1974; Welsh et al, 1998; Zhu et al, 1998; Frisbee and Lombard, 2002) and low levels of O2 result in vasodilation (Pittman and Duling, 1973; Fredricks et al, 1994; Frisbee et al, 2002) These findings allude to the existence of an O2 sensor, the location of which remains unclear (Jackson, 2016).

Objectives

Methods

Results

Conclusion