Effect of shear stress on surface membrane potassium ion permeability of calf pulmonary artery endothelial cells (Potassium ion)
This study aims to determine the effect of shear stress on membrane potassium (K$\sp+$) permeability in vascular endothelial cells. Cultured monolayers of calf pulmonary artery endothelial cells, preloaded with $\rm \sp{86}Rb\sp+$, were subjected to different levels of fluid shear stress in the range 1-10 dynes/cm$\sp2$, in a parallel-plate geometry flow chamber, and the radioactivity of the effluent was monitored with time. Increase in laminar shear stress, from 1 dyne/cm$\sp2$ to a higher level, resulted in a rapid transient increase in the rate constant for $\rm \sp{86}Rb\sp+$ release. The difference of efflux rate coefficients, between the peak and the baseline at 1 dyne/cm$\sp2$, varied with shear stress in a "dose-dependent" manner. Changes in K$\sp+$ permeability may occur via activation of shear-stress-activated K$\sp+$ channels, Ca$\sp{2+}$-activated K$\sp+$ channels, or both. The Ca$\sp{2+}$-activated K$\sp+$ channels were shown to respond to bradykinin stimulation under flow conditions. The significance of such flow studies is that they provide more knowledge about the flow-associated changes in ionic channels and intracellular second messengers in endothelial cells.
Biomedical engineering, Chemical engineering
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