2552 Catecholamine Exocytosis in the Absence
of Chromogranins A and B
The generation of double CgA&B-KO mice allowed us to analyse catecholamine
secretion in the absence of both chromogranins. Electron microscopy images of the
adrenal medulla revealed the presence of giant granules with little or no vesicular
Fig. 4 The quantum size of secretory spikes in chromaffin cells from Cgs-KO mice. Data were
obtained from mouse chromaffin cells by carbon fibre amperometry. Average number of secretory
spikes counted over 2 min following a 5 s pulse of 5 mM BaCl 2 from CgA-KO (a), CgB-KO (b)
and the double KO CgA&B (c). Data are compared with their isogenic controls (WT) by alternat-
ing WT and KO cells from the same culture day and using the same calibrated electrode. Note the
quantitative differences obtained within the experiments. *p < 0.05, **p < 0.01, Mann-Whitney
test. Cell number is indicated in brackets (Modified from (Montesinos et al. 2008 ; Diaz-Vera et al.
2010 ) and from (Diaz-Vera et al. 2012 ))
Fig. 5 Chromogranins as promoter of the neoformation of functional LDCV. (a) HEK293 cells
were incubated for 60 min with L-DOPA (100 μM, 60 min) and the lysates were prepared for
HPLC analysis. Control: non-transfected cells; CgA-EGFP cells expressing CgA-EGFP. Bar
graphs normalized the L-DOPA accumulation (measured as ng L-DOPA/μg protein): *p = 0.0022;
(Mann–Whitney U test). (b) As in a but incubating the cells with 5-HT (100 μM for 60 min)
#p = 0.0043; (Mann–Whitney U test). (c) Amperometric recording showing exocytotic events from
HEK293 cells incubated for 90 min with 1 mM of L-DOPA. This secretory activity is only detected
in cells that express CgA-EGFP (Modified from (Dominguez et al. 2014 ))
Chromogranins and Exocytosis