HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cull-Candy, S G Articles by Thesleff, S Search for Related Content PubMed PubMed Citation Articles by Cull-Candy, S G Articles by Thesleff, S

1. Botulinum toxin (BoTx) type A partially blocks spontaneous transmitter release from nerve terminals in the rat. Minature end-plate potentials (m.e.p.p.s) are present at all end-plates, initially with a low frequency but increasing with time after posoning. Their amplitude distribution is at first skew with a predominace of very small m.e.p.p.s but, after a few days, larger than normal m.e.p.p.s appear. 2. Tetanic nerve stimulation, Black Widow Spider Venom, the Caionophore A 23187 or mechanical damage to nerve terminals increases the frequency of m.e.p.p.s and alters the amplitude distribution of m.e.p.p.s towards a normal Gaussian one; the m.e.p.p. size approaches that seen at normal end-plates. This was seen at any time after poisoning. 3. Nerve stimulation gives rise to end-plate potentials (e.p.p.s) of low amplitude and high failure rate. Statistical analysis indicates that evoked release is quantal in nature and follows Poisson statistics, quantum size being initially very small, but after a few days approaching normal size. Short-term tetanic nerve stimulation reversibly increases the quantum content of e.p.p.s and during early stages of paralysis long-term (2 hr) stimulation causes an apparently permanent increase in quantum size. 4. Raising the extracellular Ca concentration from 2 to 16 mM increases the frequency of m.e.p.p.s in normal muscle but not in BoTx poisoned ones. K-free medium or ouabain, which are believed to raise the intracellular Ca concentration in nerve terminals, similarly increases m.e.p.p. frequency in normal but not in poisoned muscles. When the Ca-ionophore A 23187 is used together with high extracellular Ca (greater than 4 mM) massive release of transmitter occurs from poisoned terminals. 5. The extracellular Ca concentration which causes a certain level of transmitter release in reponse to nerve impulses is considerably higher at BoTx poisoned end-plates than at normal ones. The slope value for Ca dependence of transmitter release is about 1-5 compared with about 3 at normal end-plates. 6. Tetraethylammonium (TEA) greatly increases the amount of transmitter released by nerve impulses and restores neuromuscular transmission during all stages of poisoning, although it has not effect on spontaneous transmitter release. In the presence of TEA the power relation between Ca concentration and quantum content at the BoTx poisoned end-plate is similar to that seen at normal end-plates. 7. It is suggested that in BoTx poisoning the mechanism for transmitter release has a reduced sensitivity to Ca, and the level for activation by intracellular Ca is elevated. Once the intracellular concentration of Ca is raised to this level, by tetanic nerve stimulation, mechanical injury to nerve terminals, the Ca-ionophore or the prolongation of the nerve action potential with TEA, augmented transmitter release occurs, similar to that which occurs in normal nerve terminals at a lower level of Ca.

This article has been cited by other articles:

				E. Fdez, T. A. Jowitt, M.-C. Wang, M. Rajebhosale, K. Foster, J. Bella, C. Baldock, P. G. Woodman, and S. Hilfiker A Role for Soluble N-Ethylmaleimide-sensitive Factor Attachment Protein Receptor Complex Dimerization during Neurosecretion Mol. Biol. Cell, August 1, 2008; 19(8): 3379 - 3389. [Abstract] [Full Text] [PDF]

				J. Wang, J. Meng, G. W. Lawrence, T. H. Zurawski, A. Sasse, M. O. Bodeker, M. A. Gilmore, E. Fernandez-Salas, J. Francis, L. E. Steward, et al. Novel Chimeras of Botulinum Neurotoxins A and E Unveil Contributions from the Binding, Translocation, and Protease Domains to Their Functional Characteristics J. Biol. Chem., June 20, 2008; 283(25): 16993 - 17002. [Abstract] [Full Text] [PDF]

				H. Bao, R. W. Daniels, G. T. MacLeod, M. P. Charlton, H. L. Atwood, and B. Zhang AP180 Maintains the Distribution of Synaptic and Vesicle Proteins in the Nerve Terminal and Indirectly Regulates the Efficacy of Ca2+-Triggered Exocytosis J Neurophysiol, September 1, 2005; 94(3): 1888 - 1903. [Abstract] [Full Text] [PDF]

				T. Sakaba, A. Stein, R. Jahn, and E. Neher Distinct Kinetic Changes in Neurotransmitter Release After SNARE Protein Cleavage Science, July 15, 2005; 309(5733): 491 - 494. [Abstract] [Full Text] [PDF]

				W. C. Tucker, T. Weber, and E. R. Chapman Reconstitution of Ca2+-Regulated Membrane Fusion by Synaptotagmin and SNAREs Science, April 16, 2004; 304(5669): 435 - 438. [Abstract] [Full Text] [PDF]

				Y.-F. Xu, D. Autio, M. B. Rheuben, and W. D. Atchison Impairment of Synaptic Vesicle Exocytosis and Recycling During Neuromuscular Weakness Produced in Mice by 2,4-Dithiobiuret J Neurophysiol, December 1, 2002; 88(6): 3243 - 3258. [Abstract] [Full Text] [PDF]

				G. Schiavo, M. Matteoli, and C. Montecucco Neurotoxins Affecting Neuroexocytosis Physiol Rev, April 1, 2000; 80(2): 717 - 766. [Abstract] [Full Text] [PDF]

				K. L. Engisch, M. M. Rich, N. Cook, and M. C. Nowycky Lambert-Eaton Antibodies Inhibit Ca2+ Currents But Paradoxically Increase Exocytosis during Stimulus Trains in Bovine Adrenal Chromaffin Cells J. Neurosci., May 1, 1999; 19(9): 3384 - 3395. [Abstract] [Full Text] [PDF]

				F. Aguado, L. Gombau, G. Majo, J. Marsal, J. Blanco, and J. Blasi Regulated Secretion Is Impaired in AtT-20 Endocrine Cells Stably Transfected with Botulinum Neurotoxin Type A Light Chain J. Biol. Chem., October 10, 1997; 272(41): 26005 - 26008. [Abstract] [Full Text] [PDF]

				M. Capogna, R. A. McKinney, V. O'Connor, B. H. Gahwiler, and S. M. Thompson Ca2+ or Sr2+ Partially Rescues Synaptic Transmission in Hippocampal Cultures Treated with Botulinum Toxin A and C, But Not Tetanus Toxin J. Neurosci., October 1, 1997; 17(19): 7190 - 7202. [Abstract] [Full Text] [PDF]

				J. E. Keller and E. A. Neale The Role of the Synaptic Protein SNAP-25 in the Potency of Botulinum Neurotoxin Type A J. Biol. Chem., April 13, 2001; 276(16): 13476 - 13482. [Abstract] [Full Text] [PDF]

				B. A. Stewart, M. Mohtashami, W. S. Trimble, and G. L. Boulianne SNARE proteins contribute to calcium cooperativity of synaptic transmission PNAS, December 5, 2000; 97(25): 13955 - 13960. [Abstract] [Full Text] [PDF]