Fig. 6.

Expression of CIRL reduces secretion at all Ca²⁺ concentrations. Chromaffin cells were transfected with plasmids for hGH (pXGH5) and either pCDR7 or pCMVneo, as in Figure 2. After 4 d the cells were permeabilized with 20 μm digitonin in KGENP buffer (potassium glutamate, EGTA, nitrilotriacetic acid, and PIPES-containing solution; see Materials and Methods) without Ca²⁺ for 4 min, followed by incubation with the indicated Ca²⁺concentrations in KGENP for 15 min. MgATP (2 mm) was included in both incubations. The amounts of hGH (A) and catecholamine (B) released into the medium and the amounts remaining in the cells were determined as described; n = 4 wells/group. *p < 0.05 versus pCMVneo; **p< 0.001 versus pCMVneo; ***p < 0.0001 versus pCMVneo.