A specific Goheterotrimer couples somatostatin receptors to voltage-gated calcium channels in RINm5F cells

Abstract
The peptide hormone somatostatin inhibits glucose‐induced insulin secretion in the rat insulinoma RINm5F cells by inhibition of voltage‐gated calcium channels. Here we used microinjection of antisene oligonucleotides directed against subtypes of G‐protein subunits to determine the subunit composition involved in somatostatin‐induced inhibition of voltage‐gated calcium channels in RINmF5 cells. Injection of antisene oligonucleotides annealing to the respective mRNA of Gαo2, Gβ1 and Gγ3 reduced the somatostatin‐induced inhibition of calcium channels in these cells. Injection of antisene oligonucleotides directed against other G‐protein subunits did not, suggesting that in RINm5F cells the somatostatin receptor couples to a G protein of Gαo2β1γ3 composition. By using a selective agonist of type 2 somatostatin receptors (SSTR 2) NC 8–12, we identified this receptor as the subtype coupling to calcium channels in RINm5F cells.