Activation of G-proteins induces Ca2+ oscillations with hyperpolarizing K+ currents in pancreatic beta-cells.
1991 (English)In: Second messengers and phosphoproteins, ISSN 0895-7479, Vol. 14, no 3, 173-83 p.Article in journal (Refereed) Published
Activation of G-proteins by internal perfusion with GTP-gamma-S or external application of carbachol resulted in oscillations of cytoplasmic Ca2+ in isolated mouse pancreatic beta-cells. The Ca2+ transients were associated with the generation of K+ currents sufficiently pronounced to induce marked pulses of hyperpolarization. The oscillatory G-protein response remained largely unaffected when altering the membrane potential. The oscillations became less frequent in the presence of 1 mM neomycin and disappeared when the cells were internally perfused with 100 micrograms/ml heparin. The frequency of the oscillations was positively correlated with the basal level of cytoplasmic Ca2+. Addition of Ca2+ to the internal perfusion medium increased the oscillatory rate and buffering of the ion with Indo-1 or EGTA had the opposite effect. It is concluded that G-protein activation results in cyclic mobilisation of intracellular calcium mediated by inositol-1,4,5-triphosphate and that the basal concentration of cytoplasmic Ca2+ is an important determinant for the frequency of the oscillations.
Place, publisher, year, edition, pages
1991. Vol. 14, no 3, 173-83 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-259865PubMedID: 1345342OAI: oai:DiVA.org:uu-259865DiVA: diva2:1061352