Underlying Morphological Changes in the Arterial Wall at Bifurcations for Atherogenesis
Apical and outer wall intimas at branchings of inferior mesenteric arteries from aortas of human autopsy cases were investigated. The outer wall intima, a low shear stress region, was thicker than the apical intima, a high shear stress region, except in cases younger than one month. Deposit of ß-lipoproteins in the outer wall intima increased with age, but not that in the apical intima. Electron microscopic studies revealed that collagen fibers increased markedly in the apical intima in the third decade. Among the dense collagen fibers, intimai smooth muscle cells(SMC) exhibited contractile phenotype. The outer wall possessed mucinous intima accompanied with synthetic SMC. Atherosclerotic rabbit intimai SMC cultivated on type 1 collagen gel increased cAMP production to change phenotype from synthetic to contractile and to suppress DNA synthesis. Early lipid deposition of rabbits placed on an atherogenic diet within three weeks occurred in special linear areas of flow dividers. As a result, blood flow dynamics may induce cellular and microarchitectural changes in vessel walls which are favorable or resistant to atherogenesis.
KeywordsOuter Wall Lipid Deposition Intimal Thickness Atherogenic Diet Flow Divider
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