Characteristics of stimulation-evoked exo-endocytosis and reacidification of SLMVs in MIN6B1 cells: whole-cell studies.

<p>A. Time-course of cocktail-induced (glucose 20 mM; KCl 30 mM; forskolin 10 µM, IBMX 100 µM) pHluorin fluorescence intensity obtained with TIRF and EPI illumination. The curve represents the whole-cell pHluorin fluorescence signal, expressed as ΔF/F₀ obtained averaging results from 5 cells. B. Same as A. but in the presence of BafA1 (2.5 µM; n = 4 cells). The rate of spontaneous alkalinization (TIRF 0.08±0.006 ΔF/F₀; EPI 0.096±0.01 ΔF/F₀) was calculated in the pre-stimulus period and subtracted from the curves. Not that the curve under EPI represents a cumulative curve of exocytosis. C. Cumulative curve of estimated endocytosis (movement out of the TIRF field) obtained by subtracting the normalized curves of the pHluorin fluorescence signal measured under TIRF and under EPI both in the presence of BafA1 (curves in B). Curves in B were normalized to the maximum fluorescence obtained under EPI and TIRF, respectively in the presence of BafA1 for each cell. D. Cumulative curve of estimated reacidification obtained by subtracting the normalized curves of the pHluorin fluorescence signal obtained under EPI in the absence of BafA1 (curve in A) from the curve in the presence of the drug (curve in B). Curves in A and B were normalized to the maximum fluorescence obtained under EPI in the presence of BafA1 for each cell.