Requirement of GTP on somatostatin-induced K+ current in human pituitary tumor cells.
- 1 July 1988
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 85 (13) , 4924-4928
- https://doi.org/10.1073/pnas.85.13.4924
Abstract
The role of GTP on somatostatin-induced K+ current increase was examined in dissociated human pituitary tumor cells obtained from three acromegalic patients. Pituitary cells in culture were voltage-clamped by using the patch clamp technique in the whole-cell configuration. Somatostatin (100 nM) increased the membrane permeability to K+ ions and inhibited hormone secretion. A current-voltage relation of the somatostatin-induced K+ current showed an inward rectification when the concentration of extracellular K+ ions was increased. The amplitude of the somatostatin-induced K+ current decreased during recording when the patch pipette solution did not contain GTP; addition of 100 microM GTP to the patch pipette solution prevented this reduction. Intracellular application of 100 microM guanosine 5'-[gamma-thio]triphosphate (GTP[gamma S] evoked an inward rectifying K+ conductance in the absence of somatostatin. After the GTP[gamma S]-induced K+ conductance reached a steady level, application of somatostatin did not further increase the K+ conductance. In pertussis toxin-treated cells GTP[gamma S] did not evoke K+ conductance. It was concluded that somatostatin-induced K+ channels were regulated by a GTP-binding protein.This publication has 21 references indexed in Scilit:
- Reconstitution of Somatostatin and Muscarinic Receptor Mediated Stimulation of K+Channels by Isolated GKProtein in Clonal Rat Anterior Pituitary Cell Membranes *Molecular Endocrinology, 1987
- Direct Activation of Mammalian Atrial Muscarinic Potassium Channels by GTP Regulatory Protein G kScience, 1987
- The βγ subunits of GTP-binding proteins activate the muscarinic K+ channel in heartNature, 1987
- A single GTP-binding protein regulates K+-channels coupled with dopamine, histamine and acetylcholine receptorsNature, 1987
- The GTP-binding protein, Go9 regulates neuronal calcium channelsNature, 1987
- Block of calcium channels by enkephalin and somatostatin in neuroblastoma-glioma hybrid NG108-15 cells.Proceedings of the National Academy of Sciences, 1986
- A guanine nucleotide-binding protein mediates the inhibition of voltage-dependent calcium current by somatostatin in a pituitary cell line.Proceedings of the National Academy of Sciences, 1986
- On the mechanism of activation of muscarinic K+ channels by adenosine in isolated atrial cells: involvement of GTP-binding proteinsPflügers Archiv - European Journal of Physiology, 1986
- Hyperpolarization of the membrane potential caused by somatostatin in dissociated human pituitary adenoma cells that secrete growth hormone.Proceedings of the National Academy of Sciences, 1986
- Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patchesPflügers Archiv - European Journal of Physiology, 1981