Examination of vascular remodelling in resistance arteries using laser scanning confocal microscopy

McGrory, Simon Peter (2003) Examination of vascular remodelling in resistance arteries using laser scanning confocal microscopy. MSc(R) thesis, University of Glasgow.

Abstract

No single technique has been developed which has the ability to give the experimenter all the results needed to describe in detail the morphological characteristics of an arterial wall. All methods have their advantages and limitations therefore two or more techniques are often used to validate each other. Quantitative methods for studying remodelling in animal models were used before using human tissue since the ability to use human blood vessels can prove difficult. Patients are often not willing to provide biopsies of healthy tissue which can be compared with diseased tissue. Therefore animal models are valuable in that they allow us to obtain experimental tissue easily under control conditions. Although thinking of an artery as three distinct individual layers can be useful it is important to remember that the cellular organisation within each of these layers is very complex. Therefore, new techniques are required to advance our understanding of how an artery is constructed at the cellular level and how each individual cell plays its role in the bigger picture. By using Laser Scanning Confocal Microscopy we can show that remodelling in each of the arteries can be defined according to the Mulvany 1996 classification depending on the changes observed within the vascular wall. In anterior cerebral arteries from a rabbit model of heart failure there was an increase in lumen diameter along with increases in both thickness of the adventitial and medial layers. The overall increase in wall cross sectional area meant that the changes in the morphology of these arteries could be defined as outward hypertrophic remodelling. Third order mesenteric arteries from a rat model of heart failure show a decrease in lumen diameter along with a decrease in the density of smooth muscle cells within the ligated animals. There was no difference in the medial cross sectional area therefore arteries undergo eutrophic remodelling. Remodelling within hypertension was shown in two models. Firstly, a vasodilator study in genetically hypertensive SHRSP rats, hi third order mesenteric arteries from these animals treatment with the angiotensin II type 1 antagonist - Irbesartan, or a combination of the diuretic hydrochlorothiazide and calcium chamiel blocker hydralazine produced no change in the lumen diameter between control and experimental groups. However a significant decrease in the wall cross sectional area of both experimental groups resulted from a significant decrease in the medial layer thickness with no difference in the number of cells. These arteries undergo hypotrophic remodelling. The second model of hypertension was an inducible Fischer rat model. Infusion with Indole-3 Carbinol for 14 days results in a hypertensive state. Third order mesenteric arteries from these animals showed no difference in lumen diameter between controls and hypertensive animals. However these arteries displayed an increase in adventitial thickness along with a reduction in medial thickness resulting in no overall difference in the wall thickness as the decrease medial thickness cancelled the increased adventitial thickness. These results would suggest that mesenteric arteries from an inducible model of hypertension undergo eutrophic remodelling. What these results show is that by using Laser Scanning Confocal Microscopy more precise estimations of the type of remodelling within an aitery wall can be made. The results show that by using the classification developed by Mulvany et al, (1996) most types of remodelling can be explained but it also shows that there are gaps in the accepted classification. Remodelling within the vasodilator hypertension study can not be classified any further than hypertrophic remodelling. This is due to the fact that there was not an observed difference in the lumen diameter so remodelling can not be further described as inward or outward.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Medical imaging.
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Supervisor's Name: McGrath, Prof. J.C.
• Date of Award: 2003
• Depositing User: Enlighten Team
• Unique ID: glathesis:2003-71471
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 May 2019 14:34
• Last Modified: 10 Jun 2021 09:13
• URI: https://theses.gla.ac.uk/id/eprint/71471

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