Fig. 3.

Knockdown of VNUT preferentially impaired the vesicular exocytosis of adrenaline in chromaffin cells. (A) Typical HPLC chromatograms showing the detection of amines. (Left) External standard of noradrenaline (NA), adrenaline (A), and DHBA (internal standard). Cells were stimulated for 5 min with DMPP and the amines secreted into the media were analyzed. (Right) These traces show the catecholamines secreted from control cells (scrambled, dashed line) and VNUT-KD cells (solid line). (B) Average total catecholamine content in lysates from cells transfected with the scrambled (S) and siVNUT₁ (KD) siRNAs. ns, not significant. (C and D) Basal and DMPP-evoked noradrenaline and adrenaline secretion from cells stimulated by DMPP, showing greater release of noradrenaline. The data are the means ± SEM of at least three independent cell cultures: *P < 0.05, **P < 0.01 (Dunnett’s paired t test). (E) Linear fit from the relation catecholamines/ATP obtained from purified SGs. The R² values were 0.9 and 0.7 for ATP/adrenaline and ATP/noradrenaline, respectively. The slopes of the linear equations were 2.5 vs. 9.1, with values from an experiment from two independent gradients of isolated vesicles shown.