Figure 5.
Effect of serine/threonine kinase inhibitors on the [Na+]i-dependent Na,K-ATPase cell surface expression in mpkCCDcl4 cells. Confluent mpkCCDcl4 cells grown on polycarbonate filters were first preincubated in the presence of 15 or 135 mM Na+ without or with 10–5 M H-7, 10–6 M GF109203X (GF), or 10–5 M ML-7 for 30 min at 37°C. After permeabilization by 1 μg/ml amphotericin B cells were incubated for 1 h at 37°C. Cell surface Na,K-ATPase was detected as described in the legend of Figure 2. (A) Representative immunoblot showing Na,K-ATPase cell surface expression. (B) Bars represent densitometric values expressed as the percentage of the optical density value measured in the presence of 15 mM Na+. Results are means ± SE from six independent experiments. *p < 0.05 vs. 15 mM Na+ values.