Figure 4. Anti-G_i1/2 prevents the inhibitory action of somatostatin on exocytosis.

Effects of antibodies against the C-terminal end of the α-subunit of G_i1/2 (anti-G_i1/2; A) or non-immune IgG (IgG control; B) on changes in cell capacitance (ΔC_m) and whole-cell Ca²⁺ currents (I_Ca) elicited by 500 ms voltage-clamp depolarisations from -70 to 0 mV (V_m) in single rat α-cells. The standard whole-cell configuration was used to record changes in cell capacitance before and 2 min after the addition of somatostatin (Sst). The antibodies were allowed to diffuse into the cells for 2 min before initiation of the experiments. Cyclic AMP (0.1 mm) was included in the pipette solution dialysing the cell interior. C, histogram summarising the effects of somatostatin under control conditions (IgG-control) or following application of anti-G_i1/2 (Anti-Gα_i1/2), antibodies neutralised with the corresponding peptide of G_i1/2 (Neutr. anti-Gα_i1/2) or antibodies against G_i3/o (Anti-Gα_i3/o). Final concentration of the antibodies in the pipette solution was 17.5 μg ml⁻¹. The data are means ±s.e.m. of 5-6 different cells in each group. *P < 0.01.