Flow Effects on Prostacyclin Production by Cultured Human Endothelial Cells

Abstract

Endothelial cell functions, such as arachidonic acid metabolism, may be modulated by membrane stresses induced by blood flow. The production of prostacyclin by primary human endothelial cell cultures subjected to pulsatile and steady flow shear stress was measured. The onset of flow led to a sudden increase in prostacyclin production, which decreased to a steady rate within several minutes. The steady-state production rate of cells subjected to pulsatile shear stress was more than twice that of cells exposed to steady shear stress and 16 times greater than that of cells in stationary culture.

The role of endothelial glycocalyx components in mechanotransduction of fluid shear stress

“…Although not displayed here, the characteristic biphasic nitric oxide production response to a step onset of shear stress was observed as demonstrated previously [9]. The time course for prostacyclin response to a step onset of shear stress was also biphasic and similar to previous reports in the literature [15]. In all cases, three hours of steady shear stress induced a significant increase in nitric oxide and prostacyclin production compared to static controls (Figures 1 and 2, p<0.01 for all experimental sets).…”

“…To further test this hypothesis, we considered the shear-induced PGI 2 response of BAECs after the same enzyme treatments, realizing that shearinduced PGI 2 is another hallmark of mechanotransduction in endothelial cells [15]. To our initial surprise, we observed that none of the enzymes that blocked shear-induced NO production had any inhibitory effect on shear-induced PGI 2 production (Fig.…”

Inhibition of MAP kinase kinase (MEK) blocks endothelial PGI2 release but has no effect on von Willebrand factor secretion or E‐selectin expression

“…In the present study, inhibition of basal and agonist-induced p42 m~pk activation by PD98059 was accompanied by a parallel inhibition of PGI2 release in both 'resting' and stimulated HUVEC. Our ability to detect both p42 m~pk activation and PGI2 release in the absence of agonist is not unexpected; replacement of medium above endothelial cell monolayers subjects the cells to shear stress which is known to promote PGI2 release [23] and to enhance phosphorylation and activation of p42 m~pk [19,20]. Taken together these results demonstrate a central role for p42 m~pk in the control of PGI2 synthesis/release in HUVEC.…”

Endothelial basement membrane laminin 511 is essential for shear stress response

“…It was not possible to use laminin 411 as the cells detached under even low flow conditions due to weak adhesion. Prostacyclin is released from endothelial cells under flow‐induced shear (Frangos et al , 1985) and its expression is controlled by COX2 (Topper et al , 1996); hence, elevated COX2 expression reflects an enhanced shear response. Figure 3B shows a higher fold change in COX2 mRNA and protein expression in shear versus non‐shear conditions in HUAECs plated on laminin 511 compared with laminin 111, consistent with a role for laminin 511 in shear‐induced arterial dilation in vivo .…”