Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues

Summary

The protocol describes the use of wire myography to evaluate the transmural isometric tension of mesenteric arteries isolated from mice, with special consideration of the modulation by factors released from endothelial cells and perivascular adipose tissues.

Abstract

Altered vascular tone responsiveness to pathophysiological stimuli contributes to the development of a wide range of cardiovascular and metabolic diseases. Endothelial dysfunction represents a major culprit for the reduced vasodilatation and enhanced vasoconstriction of arteries. Adipose (fat) tissues surrounding the arteries play important roles in the regulation of endothelium-dependent relaxation and/or contraction of the vascular smooth muscle cells. The cross-talks between the endothelium and perivascular adipose tissues can be assessed ex vivo using mounted blood vessels by a wire myography system. However, optimal settings should be established for arteries derived from animals of different species, ages, genetic backgrounds and/or pathophysiological conditions.

Introduction

Dilatations and constrictions of arteries are achieved by relaxations and contractions, respectively, of their vascular smooth muscle cells. Changes in vascular responsiveness of small arteries contribute to the homeostatic regulation of arterial blood pressure by autonomic nerves and hormones present in the blood (e.g., catecholamines, angiotensin II, serotonin, vasopressin). At the local level, the vascular responses of smooth muscle cells are modulated by signals from both the endothelial cells of the intima and the adipose tissue surrounding the arteries (Figure 1).

The endothelium is not only a passive bar....

Protocol

All animals used for the following study were provided by the Laboratory Animal Unit of the Faculty of Medicine, The University of Hong Kong. Ethical approval was obtained from the departmental Committee on Use of Laboratory Animals for Teaching and Research (CULATR, no.: 4085-16).

1. Preparations

1. Preparation of drugs
   1. Store drugs appropriately as stated in the Material Safety Data Sheet (MSDS) immediately after receiving them. Dissolve the drugs in powd.......

Discussion

Apart from the endothelial cells, signals derived from PVAT play an important role in the regulation of smooth muscle tone reactivity³⁰. Healthy PVAT releases NO and anti-inflammatory adiponectin to exert an anti-contractile effect on arteries, which is lost under pathological conditions such as obesity and metabolic syndrome^31,32. In disease states, PVAT contributes to the development of endothelial dysfunction and other cardiovascular ab.......

Materials

Name	Company	Catalog Number	Comments
Acetylcholine	Sigma-Aldrich	A6625	Stock concentration: 10-1 M Working concentration: 10-10 to 10-5 M
L-NAME (Nω-nitro-L-arginine methyl ester)	Sigma-Aldrich	N5751	Stock concentration: 3 x 10-2 M Working concentration: 10-4 M
Phenylephrine	Sigma-Aldrich	P6126	Stock concentration: 10-2 M Working concentration: 10-10 to 10-5 M
U46619 (9,11-dideoxy-9α,11αmethanoepoxy prostaglandin F2α)	Enzo	BML-PG023-0001	Stock concentration: 10-5 M Working concentration: 1-3 x 10-8 M
Multiwire myograph	Danish MyoTechnology (DMT)	620M
PowerLab 4/26	ADInstruments	ML848
Labchart7	ADInstruments	-
Adipo-SIRT1 wild type mice	Laboratory Animal Unit, The University of Hong Kong	CULATR NO.: 4085-16
Silicon-coated Petri dishes	Danish MyoTechnology (DMT)
Tungsten wires	Danish MyoTechnology (DMT)	300331
Surgical tools