Influence of Endogenous Cardiac Glycosides, Digoxin, and Marinobufagenin in the Physiology of Epithelial Cells

Figure 2

Digoxin and marinobufagenin, in a nanomolar range, promote a statistically significant increase in transepithelial electrical resistance (TER) in monolayers of MDCK cells. (a, b) Relationship of TER versus time of digoxin and marinobufagenin, corresponding to the different concentrations tested, including control (0 nM). Each dot represents the average ± SE value of TER (Ohms·cm²) of nine repeats of three independent assays. The asterisks indicate a statistically significant difference obtained after comparison of the value at any concentration versus the control group (0 nM) of a given time. Statistical analyses consisted of Kruskal–Wallis one-way analysis of variance on ranks, followed by multiple comparisons versus control group (Dunnett’s method); ; . (c) Representative images of inmmunofluorescence assays of MDCK monolayers, showing the expression (green) of either claudin-2 (top row) or claudin-4 (bottom row) under three experimental conditions, either control, or treated with marinobufagenin or digoxin (100 nM) for 48 hours. (d) On the left side, a representative Western blot assay, comparing the expression of claudin-4 and actin, of lysates of MDCK monolayers at four experimental conditions, either untreated (control) at zero or after 48 hours of treatment, or after 48 hours of treatment with digoxin or marinofugfagenin 100 nM. The right part compares the mean values of standardized relative density under the four experimental conditions aforementioned.

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