关于血管内皮细胞膜张应力累加效应的实验研究

AN EXPERIMENTAL INVESTIGATION ON THE ACCUMUNATION OF TENSILE MEMBRANE STRESS IN VASCULAR ENDOTHELIAL CELLS

冯元桢等的理论分析表明 ,在一定条件下血管内皮细胞膜张应力会逆血流方向累加。此结果意义重大 ,但实验验证尚难。本文试图通过不同长度的内皮细胞单层的Invitro实验为此求得一种证据。人胚肾小球血管内皮细胞 (HGVEC)单层暴露在平面剪切流场中 (切应力水平为 0 .4 5N/m2 ) 2 4h ,两种不同长度 (10cm和 6cm)单层内皮细胞的内皮素 (ET 1)累积分泌量、平均分泌速率、最大分泌速率、最小分泌速率及分泌率变异系数以及血管紧张素II(ATII)的累积分泌量、平均分泌速率等均有显著差异。其中 ,在前述两种长度下 ,平均分泌率比值 ,ET 1为 2 .7∶1,ATII为 1.5∶1。而在 0 .6 5N/m2 切应力作用 10h条件下 ,相应的比值同为 1.5∶1。本试验结果表明在相同切应力条件下 ,单层内皮细胞长度与其蛋白质代谢有密切的相关 ,进而从一个侧面证明血管内皮细胞膜张应力存在累加效应。

Theoretical analysis by Fung Y.C. et al had shown that the tensile stress in the endothelial cell membrane was capable of growing in the direction opposite to the blood flow under certain conditions. This finding was of great importance, but it was also not easy to verify by an experiment. We reported to obtain an experimental evidence of the phenomenon by a set of in vitro experiment of endothelial cell monolayers of different length. Human glomerular vascular endothelial cells (HGVECs) were cultured, HGVEC monolayers of length of 6 cm and 10 cm were subjected to the same steady laminar shear stress of 4.5N/m 2 for 24 hours, the cumulative production, average production rate, maximum production rate, minimum production rate as well as coefficient of variation of production rate of endothelin 1 (ET 1), and the cumulative production, average production rate of angiotensin Ⅱ (ATⅡ) by endothelial cells had highly significant difference between the two kinds of cell monolayers. The average production rates of ET 1 and ATⅡ in 6 cm long group increased by 1.7 and 0.5 fold (n=26, P<0.001) over 10 cm long group respectively. After 10 hours of exposure to shear stress of 0.65N/m 2, the average production rate of both ET 1 and ATⅡ by HGVEC monolayers of 6 cm in length exceeded 0.5 fold (n=26, P <0.0001) over those of monolayers of 10 cm in length. All these demonstrated that a close relationship existed between length of endothelial cell monolayer and protein metabolism of endothelial cells, indicating the existence of cumulative effect of tensile stress in the upper endothelial cell membrane under the shear flow field.