Fig. 4
The a-p pHi-gradient in the FCE is affected by all inhibitors during S10b (SIM-experiment; CFDA). a Pseudocolour SIM-fluorescence images of S10b-follicles. Compared to the control (DMSO), blocking with glibenclamide for 20 min resulted in strong alkalisation of the FCE which was most prominent in pFC (arrowhead). b Especially glibenclamide and furosemide, but also verapamil and 9-anthroic acid led to alkalisation in all FC types. Glibenclamide and furosemide resulted in a considerably steeper a-p gradient (enlargement of the angle × 20 and × 150, respectively). Verapamil and 9-anthroic acid enhanced the a-p gradient as well, but to a lesser extent (both × 2). The increase in fluorescence intensity as well as in the inclination of the a-p gradient (× 2) caused by bafilomycin was due to the alkalisation of vesicles (see Fig. 5 b) and, therefore, to the acidification of the cytoplasm resulting in a shallower a-p gradient. Amiloride led to acidification of pFC, thus slightly reducing the angle of the a-p gradient (× 0.5) as well. For each inhibitor, at least five repetitions of the experiment were performed. Normalised values of the single experiments were merged into one evaluation (relative intensity). Mean values, shown with their standard deviation (cf. Additional file 2: Table S5), were compared using an unpaired t-test (* p < 0.05; **p < 0.01; *** p < 0.001)