Pflügers Archiv

, Volume 427, Issue 1–2, pp 129–135 | Cite as

Modulation of the inhibitory action of ATP on acetylcholine-activated current by protein phosphorylation in rat sympathetic neurons

  • Ken Nakazawa
Molecular and Cellular Physiology


Modulation by protein phosphorylation of the relation between acetylcholine (ACh)-activated current (IACh) and adenosine triphosphate-(ATP)-activated current (IATP) was investigated with the whole-cell voltage-clamp technique in rat sympathetic neurons. During simultaneous activation by 100 μM ATP of an inward current, the current evoked by 100 μM ACh was reduced to 60–70% of that in the absence of ATP. Effects of compounds that are known to modulate protein phosphorylation were tested by including them in the intracellular solution. The reduction ofIACh by ATP was not observed when K252a (1 μM), a non-selective protein kinase inhibitor, adenosine 5′-O-(3-thiotriphosphate) (ATP[γS], 1 mM) orα,β-methylene ATP (1 mM) were included in the intracellular solution. Activators of protein kinases, adenosine 3′,5′-cyclic monophosphate (cAMP, 100 μM), guanosine 3′,5′-cyclic monophosphate (cGMP, 100 μM), phorbol 12-myristate 13-acetate (PMA, 1 μM), also abolished the reduction by ATP ofIACh. The effects of okadaic acid, a protein phosphatase inhibitor, were paradoxical: okadaic acid (2 μM) itself abolished the reduction by ATP ofIACh but it “antagonized” the abolishment by cAMP or cGMP of the reduction ofIACh. Okadaic acid did not affect the disappearance of the reduction ofIACh by ATP in the presence of intracellular PMA. The results suggest that the interaction betweenIACh andIATP is regulated by protein phosphorylation/dephosphorylation. Possible mechanisms underlying the effects of these modulators of protein phosphorylation are discussed.

Key words

Nicotinic receptor channels ATP-activated channels Voltage clamp Protein phosphorylation 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Akasu T, Koketsu K (1985) Effect of adenosine triphosphate on the sensitivity of the nicotinic acetylcholine-receptor in the bullfrog sympathetic ganglion cell. Br J Pharmacol 84:525–531Google Scholar
  2. 2.
    Akasu T, Hirai K, Kotetsu K (1981) Increase of acetylcholinereceptor sensitivity by adenosine triphosphate: a novel action of ATP on ACh-sensitivity. Br J Pharmacol 74:505–507Google Scholar
  3. 3.
    Bean BP (1990) ATP-activated channels in rat and bullfrog sensory neurons: concentration dependence and kinetics. J Neurosci 10:1–10Google Scholar
  4. 4.
    Bean BP (1992) Pharmacology and electrophysiology of ATP-activated ion channels. Trends Pharmacol Sci 13:87–90Google Scholar
  5. 5.
    Bean BP, Friel DD (1990) ATP-activated channels in excitable cells. In: Narahashi T (ed) Ion channels, vol 2. Plenum, New York, pp 169–203Google Scholar
  6. 6.
    Burnstock G (1990) Noradrenaline and ATP as cotransmitters in sympathetic nerves. Neurochem Int 17:357–368Google Scholar
  7. 7.
    Burnstock G, Kennedy C (1985) A dual function for adenosine 5′-triphosphate in the regulation of vascular tone: excitatory cotransmitter with noradrenaline from perivascular nerves and locally released inhibitory intravascular agent. Circ Res 58:319–330Google Scholar
  8. 8.
    Edwards FA, Gibb AJ, Colquhoun D (1992) ATP receptor-mediated synaptic currents in the central nervous system. Nature 359:144–147Google Scholar
  9. 9.
    Eusebi F, Molinaro M, Zani BM (1985) Agents that activate protein kinase C reduce acetylcholine sensitivity in cultured myotubes. J Cell Biol 1339–1342Google Scholar
  10. 10.
    Evans RJ, Derkach V, Surprenant A (1992) ATP mediates fast synaptic transmission in mammalian neurons. Nature 357:503–505Google Scholar
  11. 11.
    Ewald DA (1976) Potentiation of postjunctional cholinergic sensitivity of rat diaphragm muscle by high-energy-phosphate adenine nucleotides. J Membr Biol 29:47–65Google Scholar
  12. 12.
    Friel DD, Bean BP (1988) Two ATP-activated conductance in bullfrog atrial cells. J Gen Physiol 91:1–27Google Scholar
  13. 13.
    Gordon L (1986) Extracellular ATP: effects, sources, and fate. Biochem 1233:309–319Google Scholar
  14. 14.
    Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recordings from cells and cell-free membrane patches. Pflügers Arch 391:85–100Google Scholar
  15. 15.
    Huganir R, Delcour AH, Greengard P, Hess GP (1986) Phosphorylation of the nicotinic acetylcholine receptor regulates its rate of desensitization. Nature 321:774–776Google Scholar
  16. 16.
    Igusa Y (1988) Adenosine 5′-triphosphate activates acetylcholine receptor channels in culturedXenopus myotomal muscle cells. J Physiol (Lond) 405:169–185Google Scholar
  17. 17.
    Inoue K, Nakazawa K (1992) ATP receptor-operated Ca2+ influx and catecholamine release from neuronal cells. News Physiol Sci 7:56–59Google Scholar
  18. 18.
    Inoue K, Nakazawa K, Watano T, Ohara-Imaizumi M, Fujimori K, Takanaka A (1992) Dopamine receptor agonists and antagonists enhance ATP-activated currents. Eur J Pharmacol 215:321–324Google Scholar
  19. 19.
    Kase H, Iwahashi K, Nakanishi S, Matsuda Y, Yamada K, Takahashi M, Murakata C, Sato A, Kaneko M (1987) K252 compounds, novel and potent inhibitors of protein kinase C and cyclic nucleotide-dependent protein kinases. Biochem Biophys Res Commun 142:436–440Google Scholar
  20. 20.
    Lu Z, Smith DO (1991) Adenosine 5′-triphosphate increases acetylcholine channel opening frequency in rat skeletal muscle. J Physiol (Lond) 436:45–56Google Scholar
  21. 21.
    Nakazawa K (1993) ATP-activated current and its interaction with acetylcholine-activated current in rat sympathetic neurons. J Neurosci (in press)Google Scholar
  22. 22.
    Nakazawa K, Fujimori K, Takanaka A, Inoue K (1991) Comparison of adenosine triphosphate- and nicotine-activated inward currents in rat phaeochromocytoma cells. J Physiol (Lond) 434:647–660Google Scholar
  23. 23.
    Nakazawa K, Watano T, Inoue K (1993) Mechanism underlying facilitation by dopamine of ATP-activated currents in rat pheochromocytoma cells. Pflügers Arch 422:458–464Google Scholar
  24. 24.
    Sasakawa N, Nakaki T, Yamamoto S, Kato R (1989) Stimulation by ATP of inositol trisphosphate accumulation and calcium mobilization in cultured adrenal chromaffin cells. J Neurochem 52:441–447Google Scholar
  25. 25.
    Swartz KJ, Merritt A, Bean BP, Lovinger DM (1992) Protein kinase C modulates glutamate receptor inhibition of Ca2+ channels and synaptic transmission. Nature 361:165–168Google Scholar
  26. 26.
    Yellen G (1982) Single Ca2+-activated nonselective cation channels in neuroblastoma. Nature 296:357–359Google Scholar

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Ken Nakazawa
    • 1
  1. 1.Department of NeurobiologyHarvard Medical SchoolBostonUSA

Personalised recommendations