Figure 3

Catecholamine secretion is reduced in SNAP-25 knockdown PC12 cells. Representative amperometric traces are shown from a control cell stably transfected with pG418-shRNA lacking an shRNA insert (empty vector) (A) and from a SNAP-25 knockdown cell prior to and during a 2.5 min stimulation with 60 mM KCl (B). To the right of each of the traces is an averaged amperometric event shown on an expanded time scale. C) When compared to empty vector controls (n = 18) the silencing of SNAP-25 in PC12 cells (n = 18) did not alter the number of norepinephrine molecules per release event. D) Silencing of SNAP-25 resulted in a 63% reduction in the total number of exocytotic events produced following stimulation. Control transfected cells and SNAP-25 knockdown cells produced a mean ± SEM of 79 ± 17 events and 29 ± 10 events, respectively. *p < 0.03 (Student's t-test). E) Transient transfection with a human SNAP-25 expression plasmid rescued the deficit in catecholamine secretion in the SNAP-25 knockdown cells. *p < 0.03 (Student's t-test).