In COS-7 cells incubated at 37°C, the effects of
PDBu on the transport activity and the cell surface expression of
Na,K-ATPase are dependent on PKCs and arachidonic acid metabolism.
COS-7 cells expressing the wild-type Bufo α1 subunit
were incubated for 30 min at 37°C in the absence (C) or presence of
10−7 M PDBu (P), 5 × 10−6 M arachidonic
acid (A), 5 × 10−7 M GF109203X (a PKC inhibitor; G),
GF109203X and PDBu (G+), 10−5 M
oleoyloxyethylphosphocholine (a phospholipase A2
inhibitor; Ol), oleoyloxyethylphosphocholine and PDBu (Ol+);
17-octadecynoic acid (a cytochrome P450 inhibitor; Od), and
17-octadecynoic acid and PDBu (Od+). (A) Exogenous Na,K-ATPase-mediated
86Rb uptake was measured in the presence of 2.5 ×
10−6 M ouabain under initial rates of influx. Results are
expressed as fractional change (with respect to control value) and are
means ± SE from 6–14 independent experiments (**, p <
0.01). (B) After streptavidin precipitation, the cell
surface–expressed Bufo α1 subunits were detected by
immunoblotting using a specific
anti-Bufo α1 subunit antibody. Results are expressed
as fractional change (with respect to control values) and are
means ± SE from six or seven independent experiments (*, p
< 0.05).