The ICM-induced changes in
J V could be solely due to the observed polarization of the cytokine receptors. To test this hypothesis, we concomitantly added IL-1β to the apical bathing solution and TNF-α, together with IFN-γ, to the solution bathing the basal side. In
Figure 6A ,
J V increased by ∼13 μL · cm
−2 · h
−1 and then recovered to baseline after washout of cytokines from both bathing solutions. This experiment showed a small cytokine-induced change in
R T but a significant change was not observed in six cytokine-treated monolayers (365 ± 97 Ω · cm
2 in control versus 368 ± 94 Ω · cm
2 in treated monolayers). In six experiments, the ICM combination increased mean
J V from 5.4 ± 1.6 to 19 ± 3.6 μL · cm
−2 · h
−1 (mean ± SEM;
P = 0.005). In control experiments, IL-1β was added to the solution bathing the basal membrane, and concomitantly, TNF-α was added together with IFN-γ to the solution bathing the apical membrane.
Figure 6Bsummarizes the data from a representative experiment with a baseline
J V of ≈15 μL · cm
−2 · h
−1. The cocktail produced no change in
J V and a small change in TEP. In four such experiments,
J V, TEP, and
R T were 12.5 ± 1.1 μL · cm
−2 · h
−1, −0.2± 0.8 mV, 516 ± 70 Ω · cm
2, respectively (mean ± SEM) in the
absence of this cytokine mixture. In each experiment, subsequent addition of cytokines produced little change.
J V, TEP, and
R T were 11.2 ± 1.1 μL · cm
−2 · h
−1, 0.6± 0.5 mV, 364 ± 80 Ω · cm
2, respectively (
P > 0.1). Therefore, mean steady state
J V, TEP, and
R T are unaltered by adding cytokines to the sides of the epithelium apparently lacking their cognate receptors.