Effect of shear stress on 86Rb+ efflux from calf pulmonary artery endothelial cells.
The effect of flow-induced shear stress on membrane K+ permeability was investigated by measuring 86Rb+ efflux in cultured calf pulmonary artery endothelial cells. Cells were subjected to step changes in shear stress from 1 dyn/cm2 to 2.4, 4.8, or 10 dyn/cm2 in a parallel-plate flow chamber. Increasing shear stress produced a graded, transient increase in 86Rb+ efflux which peaked within 1 min and subsequently declined rapidly toward pre-stimulus levels. Upon returning shear stress to 1 dyn/cm2, 86Rb+ efflux initially decreased, but returned slowly to basal values. In contrast, application of bradykinin at a constant shear stress of 1 dyn/cm2 produced a transient increase in 86Rb+ efflux that was followed by a sustained elevated phase during which time efflux gradually returned to pre-stimulus levels. In order to exclude the possibility that the transient increase in 86Rb+ efflux with shear stress simply reflects a flow-dependent change in the washout of radiotracer, the transient convection-diffusion equation was solved using finite element simulation. When the flux of 86Rb+ from the cell monolayer was assumed to be constant with time, the mathematical model predicted an increase in efflux rate coefficients upon step increases in flow that were only 7-19% of that observed experimentally. The numerical predictions correlated well with the experimentally obtained peaks when the flux of 86Rb+ from the cell monolayer was simultaneously increased with flow to a new steady value. These simulations however, could not predict the transient nature of the response to increased shear stress.(ABSTRACT TRUNCATED AT 250 WORDS)
Alevriadou
B R
BR
Department of Chemical Engineering, Rice University, Houston, TX.
Eskin
S G
SG
McIntire
L V
LV
Schilling
W P
WP
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002417:Cattle; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D003198:Computer Simulation; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005069:Evaluation Studies as Topic; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D015759:Ionomycin / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D012212:Rheology; D012414:Rubidium Radioisotopes / Q000378:metabolism*; D013997:Time Factors
D012414:Rubidium Radioisotopes; D015759:Ionomycin; D011188:Potassium; D001920:Bradykinin