Acidic Extracellular pH Promotes Activation of Integrin αvβ3
Figure 6
Cell spreading, morphology, and migration speed are altered at acidic extracellular pH.
(A) Cell area for a representative cell over 8 hours, during which media pH was changed to pH 6.0 every hour. After each pH change, media pH drifted up to ∼7.2 due to presence of bicarbonate buffer, as evidenced by the color change of the pH indicator in the media (shown for 1 hour). Images are snapshots of the cell at area minima and maxima. Arrowheads indicate point immediately before media pH was brought down to pH 6.0. Each hour, cell area increased immediately after pH was dropped to 6.0, and decreased as pH drifted up. (B) Mean cell circularity 8 hours after changing media pH for adhered αvβ3 CHO-B2 cells. Cell circularity was significantly lower at pH 6.5 than at pH 7.4 (asterisk indicates p = 0.0002). Images are representative for cells at pH 6.5 and pH 7.4. (C) Mean cell migration speed as a function of fibronectin coating concentration. Maximum migration speed occurred at a lower fibronectin concentration when cells were in acidic pH. Statistical significance of maximum migration speed value at pH 7.4: 0.1 vs. 1 µg/ml, p<0.05; 1 vs. 20 µg/ml, p<0.001; 1 vs. 30 µg/ml, p<0.001. For pH 6.5: 0.1 vs. 1 µg/ml, p<0.1; 0.1 vs. 10 µg/ml, p<0.05; 0.1 vs. 20 µg/ml, p<0.001; 0.1 vs. 30 µg/ml, p<0.001. All error bars represent SEM.