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 was 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 overnight in 0.5% fetal bovine serum in Dulbecco's modified Eagle's medium with an extracellular potassium concentration of 4 mmol/L. With increasing potassium concentration, migration was significantly inhibited (P<0. 02, 2-way ANOVA). 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 potassium concentration=100%) in medium containing 3 to 6 mmol/L extracellular potassium concentration (P<0. 03). Long-term potassium exposure was investigated 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 weeks. Migration was assessed with 0 or 20 ng/mL PDGF-BB. Migration was significantly inhibited by the elevation of extracellular potassium concentration (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 potassium (P<0.01). Increases in extracellular potassium concentration within the physiological range significantly and directly inhibit vascular smooth muscle cell migration.