FIGURE 6.

Role of PKC in exocytosis induced by trypsin. A, PDEC were preincubated with 20 μm BAPTA-AM for 1 h at 37 °C and then treated with 1 μm trypsin. [Ca²⁺]_i averaged from four cells (solid line). Exocytosis (gray bars) is the average from 21 cells. B, PDEC were pretreated with both 5 μm thapsigargin for 5 min to deplete intracellular Ca²⁺ stores and 10 μm La³⁺ to block Ca²⁺ influx through SOC and then treated with 1 μm trypsin. Similar to panel A, [Ca²⁺]_i was averaged from 3 cells, and exocytosis was averaged from 18 cells. C, PDEC were pretreated with 20 μm BAPTA-AM and then treated with 100 nm of the PKC inhibitor BIS I for 3 min before application of 1 μm trypsin. [Ca²⁺]_i was averaged from four cells, and exocytosis was averaged from 6 cells. D, mediation of Ca²⁺-independent exocytosis by PKC, not PKA. PDEC pretreated with 20 μm BAPTA-AM and treated with 1 μm trypsin in the absence (control) or presence of different protein kinase inhibitors (100 nm BIS I, n = 6; 500 nm BIS V, an inactive BIS I analogue, n = 9; 10 μm calphostin C (Cal. C), n = 6; 30 μm Rottlerin, n = 6;1 mm Rp-8-Br-cAMPS, n = 13). Relative exocytosis was calculated for the first 3 min after trypsin treatment. The asterisk (^*) denotes the significant statistical difference compare with BAPTA control (Control, p < 0.05).