Functional Evidence of Multidrug Resistance Transporters (MDR) in Rodent Olfactory Epithelium
Figure 4
MDR inhibitors enhanced calcein accumulation in olfactory receptor neurons (ORNs) of mouse and rat. A:
Pseudocolored fluorescence micrograph of a part of an olfactory slice from rat in the presence of MK571 (50 µM) at the 60 min time point. Arrowheads point to ORNs appearing as pear-shaped cells with visible knob-bearing dendritic structures. Fluorescence image adjusted for contrast, pseudocolor bar scales from low (blue) to high (red) intensities. LP = lamina propria, scale bar in A = 20 μm. B: Fluorescence scaling is different for the two images, the value of the pseudocolor bar scales 0 to 1500 for the left panel and micrograph of a single mouse ORN in the presence of calcein-AM (left panel) and a row of ORNs in the presence of cyclosporin A (right panel). Both images are taken at the 60 min time point. Note, that the 0 to 4095 for the right panel. Scale bar in the left panel = 5 µm, and 10 µm in the right panel. C: Intracellular inhibitor-dependent increase in fluorescence intensities was evaluated from regions of interest (ROIs) placed over the cell bodies of ORNs at the 60 min time point. Bars represent the averaged inhibitor-to-control ratios of calcein fluorescence intensities in mouse (upper panel) and rat (lower panel) for four tested inhibitors: vera = verapamil at 100 and 200 µM, CsA = cyclosporin A at 5 and 10 µM, prob = probenecid at 2.5 and 5 mM, and MK = MK571 at 25 and 50 µM. * p<0.05.