The phenomenon of cell membrane tensile stress accumulation and its effect on endothelin-1 secretion by vascular endothelial cells

Theoretical analysis has shown that that the tensile stress in the upper cell membrane of the vascular endothelium could accumulate upstream to a very high level despite of the identical shear environments. This phenomenon is called cell membrane tension accumulation (CMTA). To verify the theoretical analysis, the secretion of endothelin-1 (ET-1) by a paired human umbilical vein segments with different lengths (10 and 15 cm, respectively) were measured. The results clearly showed highly significant differences in the secretion rates of ET-1 between the 10 cm-long vein (segment A) and the 15 cm-long vein (segment B) under the same shear stress level of 0.48 N/m². When exposed to a shear stress of 0.48 N/m² for 24 h, segment B secreted ET-1 at an average rate of 34.9154±0.9830 pg/cm² h, almost 14% higher than the average rate of 30.6274±0.4912 pg/cm² h recorded by segment A (P<0.01). The present study, therefore, confirms that CMTA does in fact occur in the blood vessel. This phenomenon affects the secretion of ET-1 by vascular endothelial cells, and may be more important than shear stress in its effect on the metabolism and biological function of endothelial cells.