Fig. 2.

Sidedness of PGE2-induced I_sc in mIMCD-K2 cells. A: dashed trace demonstrates the I_sc response to sequential addition of PGE2 to the basal (b) bath and then to the apical bath (a); solid trace demonstrates the I_sc response to sequential addition of PGE2 to the apical bath and then to the basal bath. Additions of CI-172 (10⁻⁵ M) and FFA (2 × 10⁻⁴ M) to the apical side are shown. B: average transient (open bars) and sustained (solid bars) I_sc responses to addition of PGE2 to the apical bath (I_sc^PGE2). On the x-axis, “-” indicates absence of preexposure to PGE2; BLM indicates preexposure to basolateral PGE2. *Value significantly different from that induced by sequential addition of PGE2 in the reverse order. C: average transient (open bars) and sustained (solid bars) I_sc responses to addition of PGE2 to the basal bath (I_sc^PGE2). On the x-axis, AM indicates preexposure to apical PGE2. Values are represented as means ± SE (n = 16–18 filters). *Value significantly different from that induced by sequential addition of PGE2 in the reverse order. D: average conductance across mIMCD-K2 cell sheets after sequential addition of amiloride (Amil) and PGE2 to the apical and basal sides. Conductances in mS/cm² were measured at the peak of transient (trans) and sustained (sust) I_sc responses after addition of PGE2 (7.7 × 10⁻⁸ M). Values are means ± SE (n = 11). *Value significantly different from addition of PGE2 to the apical side. Conductance values were also significantly different between cells receiving amiloride vs. amiloride and apical PGE2. E: average conductance across mIMCD-K2 cell sheets after sequential addition of amiloride and PGE2 to the basal and apical sides. Conductances in mS/cm² were measured at the peak of transient and sustained I_sc responses after addition of PGE2 (7.7 × 10⁻⁸ M). Values are means ± SE (n = 11). Conductance after apical addition of PGE2 was not significantly different from that after basal addition (NS).