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. 1988 Jul;85(13):4924–4928. doi: 10.1073/pnas.85.13.4924

Requirement of GTP on somatostatin-induced K+ current in human pituitary tumor cells.

N Yamashita 1, N Shibuya 1, E Ogata 1
PMCID: PMC280550  PMID: 2898785

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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bassetti M., Spada A., Arosio M., Vallar L., Brina M., Giannattasio G. Morphological studies on mixed growth hormone (GH)- and prolactin (PRL)-secreting human pituitary adenomas. Coexistence of GH and PRL in the same secretory granule. J Clin Endocrinol Metab. 1986 Jun;62(6):1093–1100. doi: 10.1210/jcem-62-6-1093. [DOI] [PubMed] [Google Scholar]
  2. Byerly L., Hagiwara S. Calcium currents in internally perfused nerve cell bodies of Limnea stagnalis. J Physiol. 1982 Jan;322:503–528. doi: 10.1113/jphysiol.1982.sp014052. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Dolphin A. C., Scott R. H. Calcium channel currents and their inhibition by (-)-baclofen in rat sensory neurones: modulation by guanine nucleotides. J Physiol. 1987 May;386:1–17. doi: 10.1113/jphysiol.1987.sp016518. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Fenwick E. M., Marty A., Neher E. Sodium and calcium channels in bovine chromaffin cells. J Physiol. 1982 Oct;331:599–635. doi: 10.1113/jphysiol.1982.sp014394. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Hagiwara S., Ohmori H. Studies of calcium channels in rat clonal pituitary cells with patch electrode voltage clamp. J Physiol. 1982 Oct;331:231–252. doi: 10.1113/jphysiol.1982.sp014371. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  7. Hescheler J., Rosenthal W., Trautwein W., Schultz G. The GTP-binding protein, Go, regulates neuronal calcium channels. 1987 Jan 29-Feb 4Nature. 325(6103):445–447. doi: 10.1038/325445a0. [DOI] [PubMed] [Google Scholar]
  8. Koch B. D., Dorflinger L. J., Schonbrunn A. Pertussis toxin blocks both cyclic AMP-mediated and cyclic AMP-independent actions of somatostatin. Evidence for coupling of Ni to decreases in intracellular free calcium. J Biol Chem. 1985 Oct 25;260(24):13138–13145. [PubMed] [Google Scholar]
  9. Kurachi Y., Nakajima T., Sugimoto T. On the mechanism of activation of muscarinic K+ channels by adenosine in isolated atrial cells: involvement of GTP-binding proteins. Pflugers Arch. 1986 Sep;407(3):264–274. doi: 10.1007/BF00585301. [DOI] [PubMed] [Google Scholar]
  10. Lewis D. L., Weight F. F., Luini A. A guanine nucleotide-binding protein mediates the inhibition of voltage-dependent calcium current by somatostatin in a pituitary cell line. Proc Natl Acad Sci U S A. 1986 Dec;83(23):9035–9039. doi: 10.1073/pnas.83.23.9035. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Logothetis D. E., Kurachi Y., Galper J., Neer E. J., Clapham D. E. The beta gamma subunits of GTP-binding proteins activate the muscarinic K+ channel in heart. Nature. 1987 Jan 22;325(6102):321–326. doi: 10.1038/325321a0. [DOI] [PubMed] [Google Scholar]
  12. Mihara S., North R. A., Surprenant A. Somatostatin increases an inwardly rectifying potassium conductance in guinea-pig submucous plexus neurones. J Physiol. 1987 Sep;390:335–355. doi: 10.1113/jphysiol.1987.sp016704. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Pfaffinger P. J., Martin J. M., Hunter D. D., Nathanson N. M., Hille B. GTP-binding proteins couple cardiac muscarinic receptors to a K channel. Nature. 1985 Oct 10;317(6037):536–538. doi: 10.1038/317536a0. [DOI] [PubMed] [Google Scholar]
  14. Sasaki K., Sato M. A single GTP-binding protein regulates K+-channels coupled with dopamine, histamine and acetylcholine receptors. Nature. 1987 Jan 15;325(6101):259–262. doi: 10.1038/325259a0. [DOI] [PubMed] [Google Scholar]
  15. Spada A., Sartorio A., Bassetti M., Pezzo G., Giannattasio G. In vitro effect of dopamine on growth hormone (GH) release from human GH-secreting pituitary adenomas. J Clin Endocrinol Metab. 1982 Oct;55(4):734–740. doi: 10.1210/jcem-55-4-734. [DOI] [PubMed] [Google Scholar]
  16. Tsunoo A., Yoshii M., Narahashi T. Block of calcium channels by enkephalin and somatostatin in neuroblastoma-glioma hybrid NG108-15 cells. Proc Natl Acad Sci U S A. 1986 Dec;83(24):9832–9836. doi: 10.1073/pnas.83.24.9832. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Yamashita N., Kojima I., Shibuya N., Ogata E. Pertussis toxin inhibits somatostatin-induced K+ conductance in human pituitary tumor cells. Am J Physiol. 1987 Jul;253(1 Pt 1):E28–E32. doi: 10.1152/ajpendo.1987.253.1.E28. [DOI] [PubMed] [Google Scholar]
  18. Yamashita N., Shibuya N., Ogata E. Hyperpolarization of the membrane potential caused by somatostatin in dissociated human pituitary adenoma cells that secrete growth hormone. Proc Natl Acad Sci U S A. 1986 Aug;83(16):6198–6202. doi: 10.1073/pnas.83.16.6198. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Yatani A., Codina J., Brown A. M., Birnbaumer L. Direct activation of mammalian atrial muscarinic potassium channels by GTP regulatory protein Gk. Science. 1987 Jan 9;235(4785):207–211. doi: 10.1126/science.2432660. [DOI] [PubMed] [Google Scholar]
  20. Yatani A., Codina J., Sekura R. D., Birnbaumer L., Brown A. M. Reconstitution of somatostatin and muscarinic receptor mediated stimulation of K+ channels by isolated GK protein in clonal rat anterior pituitary cell membranes. Mol Endocrinol. 1987 Apr;1(4):283–289. doi: 10.1210/mend-1-4-283. [DOI] [PubMed] [Google Scholar]

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