FIGURE 6.

Effect of Vasopressin receptors on glycerol permeability. Osmotically induced volume changes recorded by the calcein-quenching method in HCT8 cells exposed to dDAVP stimulation or cotreated with V1aR antagonist (dDAVP/TLV) or VR2 antagonist (dDAVP/SR49059) compared to control conditions (untreated, DMSO). On the left, a representative time course of cell shrinking (water exit) followed by cell swelling indicative of the osmotic influx of water promoted by glycerol entry along its gradient (Δ 100 mOsm/L). On the right, a bar plot showing the mean ± S.E.M. values of the cell swelling time constants (1/τ, s^-1) reflecting glycerol entry into the cells. Note that the treatment with 100 nM dDAVP significantly reduced glycerol permeability. A comparable effect was observed after cotreatment with 100 nM dDAVP and 100 nM tolvaptan for 72 h. By contrast, treatment with 100 nM SR49059 for 72 h prevented the dDAVP effect on glycerol uptake. Data are obtained from 35 to 56 different measurements of 3 independent experiments. A one-way ANOVA and Dunnett’s Multiple Comparison test were performed (****p < 0.0001 vs. untreated; ^#### p < 0.0001 vs. DMSO).