Inhibition of vascular smooth muscle cell migration by elevation of extracellular potassium concentration

The effect of potassium on the migration of vascular smooth muscle cells wa s analyzed in media made with extracellular potassium concentrations of 3, 4, 5, and 6 mmol/L. The migration of cultured porcine coronary artery cells was stimulated with platelet-derived growth factor (PDGF)-BB. In the first study, cells were exposed to PDGF-BB at concentrations of 0, 10, or 20 ng/ mL for 5 hours with the use of a Boyden chamber. Cells were quiescent overn ight in 0.5% fetal bovine serum in Dulbecco's modified Eagle's medium with an extracellular potassium concentration of 4 mmol/L. With increasing potas sium concentration, migration was significantly inhibited (P<0.02, 2-way AN OVA). In the cells exposed to 10 ng/mL PDGF-BB, migration ranged from 500+/ -86% to 294+/-44% (value in wells with 0 ng/mL PDGF-BB and 4 mmol/L potassi um concentration=100%) in medium containing 3 to 6 mmol/L extracellular pot assium concentration (P<0.03). Long-term potassium exposure was investigate d in cells grown in 5% serum in Dulbecco's modified Eagle's medium with an extracellular potassium concentration of 3, 4, 5, or 6 mmol/L for 3 to 4 we eks. Migration was assessed with 0 or 20 ng/mL PDGF-BB. Migration was signi ficantly inhibited by the elevation of extracellular potassium concentratio n (P<0.01, 2-way ANOVA). With 20 ng/mL PDGF-BB, the migration rates ranged from 152+/-11% in medium with 3 mmol/L potassium to 69+/-5% in 6 mmol/L pot assium (P<0.01), Increases in extracellular potassium concentration within the physiological range significantly and directly inhibit vascular smooth muscle cell migration.