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Hypertensive structural changes in blood vessels: do endothelial cells hold the key?
1Department of Anatomy, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Insights
The endothelium, the inner lining of blood vessels, plays a critical role in vascular disease development. Altered endothelium in hypertension and diabetes contributes to complications like atherosclerosis.
Area of Science:
- Cardiovascular Biology
- Endothelial Function
- Vascular Pathology
Background:
- Vascular smooth muscle cells were historically the focus of research, but recent findings highlight the endothelium's complexity and importance.
- The endothelium's role in maintaining or altering blood vessel architecture is increasingly recognized.
- This study proposes the endothelium as a key factor in the development of vascular diseases, including those associated with diabetes mellitus.
Purpose of the Study:
- To investigate the hypothesis that the endothelium is central to vascular disease.
- To examine the role of an altered endothelium in the vascular complications of diabetes mellitus.
- To analyze endothelial changes and early atherogenic pathology in deoxycorticosterone acetate-induced hypertension in rats.
Main Methods:
- Transmission electron microscopy of coronary artery and thoracic aorta in male Wistar rats.
- Scanning electron microscopy of the thoracic aorta's luminal surface.
- Assessment of adherent monocytes as indicators of endothelial alteration.
Main Results:
- Hypertensive changes and early atherogenic pathology were observed in the absence of dietary modifications.
- Adherent monocyte-macrophages, including typical monocytes and larger macrophages, were identified on the thoracic aorta's luminal surface.
- Monocytes were found to infiltrate the endothelium, forming subendothelial foam cells and phagocytosing macrophages.
- Endothelial adherence of monocytes was significantly elevated in diabetic animals compared to controls.
Conclusions:
- The endothelium is implicated as a key factor in vascular disease.
- An altered endothelium is likely pivotal in the vascular complications associated with diabetes mellitus.
- Hypertension and diabetes induce endothelial alterations, evidenced by monocyte adherence and early atherogenic changes.
Abstract:
In recent decades, the complexity of the endothelium and its major role in maintaining or altering blood vessel architecture are being revealed. In contrast, the vascular smooth muscle cell previously received the most attention. I suggest support of the hypothesis that the endothelium is the key to vascular disease. An altered endothelium in diabetes mellitus likewise is likely to be pivotal in vascular complications that develop. We have demonstrated that adherent monocytes, indicators of altered endothelium, occur in deoxycorticosterone acetate induced hypertension in male Wistar rats. The coronary artery and thoracic aorta were investigated using transmission electron microscopy. Details of hypertensive changes were revealed as well as early atherogenic pathology in the absence of dietary modifications. Scanning electron microscopy of thoracic aorta showed details of the luminal endothelial surface and adherent monocyte-macrophages in hypertensive animals. There were two cell types: numerous typical monocytes with upstream tails, and larger cells that may have been free grazing macrophages or macrophages that had returned to the circulation. Debris and amorphous material were particularly evident in vessels from hypertensive animals. Monocytes squeezed between intact endothelial plasma membranes (as seen in section), and were found as subendothelial foam cells and phagocytosing macrophages. The endothelial adherence of monocytes to the aortas from diabetic animals was significantly (p less than 0.05) elevated over that found in controls (but not different from control-hypertensive or diabetic-hypertensive animals) supporting the concept of altered endothelium in diabetes.