Fig. 10.

Effect of overexpressed G-protein-coupled receptors on secretion from digitonin-permeabilized chromaffin cells. Chromaffin cells were transfected with plasmids for hGH (pXGH5) and the α₂ adrenergic receptor, the bombesin receptor, or pCMVneo, as in Figure 2. After 4 d the cells were permeabilized (A) with 20 μm digitonin in KGEP buffer without Ca²⁺ and with 2 mm MgATP for 4 min, followed by incubation with or without 30 μmCa²⁺ in KGEP containing 2 mm MgATP for 2 min. B, Intact cells transfected with either pCMVneo or bombesin receptor were challenged for 12 min with 20 nmbombesin in PSS containing 2.2 mm Ca²⁺and 0.5 mm Mg²⁺. The amounts of hGH and catecholamine (data not shown) released into the medium and the amounts remaining in the cells were determined as described;n = 4 wells/group.