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Fibronectin expression and aortic wall elastic modulus in spontaneously hypertensive rats
Y Bézie1, J M Lamazière, S Laurent
1Institut National de la Santé et de la Recherche Médicale, U337, Paris, France.
Arteriosclerosis, Thrombosis, and Vascular Biology
|July 22, 1998
Summary
Hypertension in rats does not alter aortic wall mechanics, but increases fibronectin and alpha5-integrin. These changes may help adapt the arterial wall to higher stress levels.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Extracellular Matrix Biology
Background:
- Arterial wall remodeling in hypertension is complex, involving changes in mechanical properties and extracellular matrix composition.
- Previous studies suggest arterial remodeling may not inherently reduce distensibility, implying altered material properties.
Purpose of the Study:
- To investigate changes in elastic properties (incremental elastic modulus) and extracellular matrix components (fibronectin, alpha5beta1-integrin) in the aorta of spontaneously hypertensive rats (SHRs).
- To determine the relationship between incremental elastic modulus and circumferential wall stress in SHRs compared to normotensive Wistar rats.
Main Methods:
- High-resolution echo-tracking system to measure in vivo pulsatile blood pressure and arterial diameter.
- In vitro medial cross-sectional area measurements.
- Calculation of incremental elastic modulus-stress curves.
- Immunohistochemistry and Western blot analysis for fibronectin and alpha5-integrin.
- Quantification of elastin and collagen densities.
- Analysis of fibronectin and alpha5-integrin mRNA levels.
Main Results:
- Spontaneously hypertensive rats exhibited higher mean stress and incremental elastic modulus compared to Wistar rats.
- Incremental elastic modulus-stress curves were superimposable between SHRs and Wistar rats, indicating equivalent material mechanical behavior.
- Increased total fibronectin, EIIIA fibronectin isoform, and alpha5-integrin were observed in SHRs aortas.
- No significant changes in elastin and collagen densities were detected between the groups.
- Messenger RNA levels for fibronectin and alpha5-integrin did not differ between SHRs and Wistar rats.
Conclusions:
- The aortic wall material in SHRs and Wistar rats possesses equivalent mechanical properties.
- SHRs experience higher levels of aortic wall stress.
- Increased fibronectin may enhance cell-matrix attachment, contributing to mechanical adaptation in the hypertensive rat aorta.