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A Varicosity Ensemble Model of Sympathetic Neuromuscular Transmission

  • Lennart Stjärne
Part of the Advances in Behavioral Biology book series (ABBI, volume 53)

Abstract

Varicosities within sympathetic nerve terminals appear to differ widely in function, e.g., in secretory responsiveness to action potentials.1 By recording excitatory junction currents (EJCs) at visualised nerve terminals in mouse vas deferens, the probability of release of a quantum of ATP from single varicosities (p ATP ) was found to be highly nonuniform, in a few 0.1–0.5 but in most 0.01 or less.2 ATP-mediated responses to nerve impulse trains may thus be evoked by repeated release of ATP quanta from ‘strong’ varicosities while weak’ varicosities remain ‘silent’ (hotspot transmission). The question is if this applies as well to transmission mediated by co-released noradrenaline (NA).3

Keywords

Carbon Fibre Sympathetic Nerve Terminal Neuronal Reuptake Sympathetic Nerve Release Secretory Responsiveness 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    M.R. Bennett, Autonomic neuromuscular transmission at a varicosity, Prog. Ncurobiol., 50, 505–532 (1996).CrossRefGoogle Scholar
  2. 2.
    N.A. Lavidis, and M.R. Bennett, Probabilistic secretion of quanta from visualised varicosities along single sympathetic nerve terminals. J. Auton. Nerv. Syst., 43, 41–50 (1993).PubMedCrossRefGoogle Scholar
  3. 3.
    L. Stjärne, and E. Stjärne, Geometry, kinetics and plasticity of release and clearance of ATP and noradrenaline as sympathetic cotransmitters: roles for the neurogenic contraction, Prog. Ncurobiol., 47, 45–94 (1995).CrossRefGoogle Scholar
  4. 4.
    P. Alberts, T. Bartfai, and L. Stjärne, Site(s) and ionic basis of oe-autoinhibition and facilitation of [3H]-noradrenaline secretion in guinea-pig vas deferens, J. Physiol., 312, 297–334 (1981)PubMedGoogle Scholar
  5. 5.
    L. Stjärne, Do sympathetic nerves release noradrenaline in ‘quanta’? J. Auton. Nerv. Syst., 81, 236–243 (2000).PubMedCrossRefGoogle Scholar
  6. 6.
    M. Msghina, F. Gonon, and L. Stjärne, Facilitation and depression of ATP and noradrenaline release from sympathetic nerves of rat tail artery, J. Physiol., 515(2), 523–531 (1999).PubMedCrossRefGoogle Scholar
  7. 7.
    S.E. Luff, and E.A. McLachlan, Frequency of neuromuscular junctions on arteries of different dimensions in the rabbit, guinea-pig and rat, Blood Vessels, 26, 95–106 (1989).PubMedGoogle Scholar
  8. 8.
    J.X. Bao, F. Gonon, and L. Stjärne, Frequency- and train length-dependent variation in the roles of postjunctional a,- and α2-adrenoceptors for the field stimulation-induced neurogenic contraction of rat tail artery, Naunyn-Schmiedeberg’s Arch. Pharmacol., 347, 601–616 (1993).CrossRefGoogle Scholar
  9. 9.
    L. Stjärne, J.X. Bao, F. Gonon, and M. Msghina, Nerve activity-dependent variations in clearance of released noradrenaline: regulatory roles for sympathetic neuromuscular transmission in rat tail artery. Ncuroscicncc, 60(4), 1021–1038 (1994).CrossRefGoogle Scholar
  10. 10.
    M.A. Hansen, J.L. Dutton, V.J. Valcar, J.A. Barden, and M.R. Bennett, P2x (purinergic) receptor distribution in rat blood vessels. J. Auton. Nerv. Syst., 75, 147–155 (1999).PubMedCrossRefGoogle Scholar
  11. 11.
    11.M. Msghina, F. Gonon, and L. Stjärne, A novel electrophysiological approach to monitor pulse by pulse the concentration of released NA at the presynaptic α2-adrenoceptors of sympathetic nerves in rat tail artery, Naunyn-Schmiedeberg’s Arch. Pharmacol., 351, 173–185 (1995).CrossRefGoogle Scholar
  12. 12.
    J.A. Brock, and T.C. Cunnane, Local application of drugs to sympathetic nerve terminals: an electrophysiological analysis of the role of prejunctional α-adrenoceptors in the guinea-pig vas deferens, Br. J. Pharmacol., 102, 595–600 (1991).PubMedCrossRefGoogle Scholar
  13. 13.
    K.L. Brain, and M.R. Bennett, Calcium in sympathetic varicosities of mouse vas deferens during facilitation, augmentation and autoinhibition, J. Physiol., 502(3), 521–536 (1997).PubMedCrossRefGoogle Scholar
  14. 14.
    S.C. O’Connor, K.L. Brain, and M.R. Bennett, Individual sympathetic varicosities possess different sensitivities to alpha 2 and P2 receptor agonists and antagonsits in mouse vas deferens. Br. J. Pharmacol., 128, 1739–1753 (1999).PubMedCrossRefGoogle Scholar
  15. 15.
    A.R. Martin, Junctional transmission II. Presynaptic mechanisms. In Handbook of Physiology, pp. 329–355 (1977).Google Scholar

Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Lennart Stjärne
    • 1
  1. 1.Dpt of Physiology and PharmacologyKarolinska InstitutetSweden

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