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

This Article Full Text Full Text (PDF) All Versions of this Article: 91/4/1500    most recent 01019.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science 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 Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Zhao, Y. Articles by Klein, M. Search for Related Content PubMed PubMed Citation Articles by Zhao, Y. Articles by Klein, M.

Changes in the Readily Releasable Pool of Transmitter and in Efficacy of Release Induced by High-Frequency Firing at Aplysia Sensorimotor Synapses in Culture

Department of Physiological Science, UCLA, Los Angeles, California 90095-1606

Submitted 22 October 2003; accepted in final form 25 November 2003

Synaptic transmission at the sensory neuron-motor neuron synapses of Aplysia, like transmission at many synapses of both vertebrates and invertebrates, is increased after a short burst of high-frequency stimulation (HFS), a phenomenon known as posttetanic potentiation (PTP). PTP is generally attributable to an increase in transmitter release from presynaptic neurons. We investigated whether changes in the readily releasable pool of transmitter (RRP) contribute to the potentiation that follows HFS. We compared the changes in excitatory postsynaptic potentials (EPSPs) evoked with action potentials to changes in the RRP as estimated from the asynchronous transmitter release elicited by a hypertonic solution. The changes in the EPSP were correlated with changes in the RRP, but the changes matched quantitatively only at connections whose initial synaptic strength was greater than the median for all experiments. At weaker connections, the increase in the RRP was insufficient to account for PTP. Weaker connections initially released a smaller fraction of the RRP with each EPSP than stronger ones, and this fraction increased at weaker connections after HFS. Moreover, the initial transmitter release in response to the hypertonic solution was accelerated after HFS, indicating that the increase in the efficacy of release was not restricted to excitation-secretion coupling. Modulation of the RRP and of the efficacy of release thus both contribute to the enhancement of transmitter release by HFS.

This article has been cited by other articles:

				A. Khoutorsky and M. E. Spira Activity-dependent calpain activation plays a critical role in synaptic facilitation and post-tetanic potentiation Learn. Mem., January 29, 2009; 16(2): 129 - 141. [Abstract] [Full Text] [PDF]

				A. Sakurai and P. S. Katz State-, Timing-, and Pattern-Dependent Neuromodulation of Synaptic Strength by a Serotonergic Interneuron J. Neurosci., January 7, 2009; 29(1): 268 - 279. [Abstract] [Full Text] [PDF]

				D. Fioravante, R.-Y. Liu, A. K. Netek, L. J. Cleary, and J. H. Byrne Synapsin Regulates Basal Synaptic Strength, Synaptic Depression, and Serotonin-Induced Facilitation of Sensorimotor Synapses in Aplysia J Neurophysiol, December 1, 2007; 98(6): 3568 - 3580. [Abstract] [Full Text] [PDF]

				R. L. P. Habets and J. G. G. Borst Dynamics of the readily releasable pool during post-tetanic potentiation in the rat calyx of Held synapse J. Physiol., June 1, 2007; 581(2): 467 - 478. [Abstract] [Full Text] [PDF]

				A. Khoutorsky and M. E. Spira Calcium-activated proteases are critical for refilling depleted vesicle stores in cultured sensory-motor synapses of Aplysia Learn. Mem., July 1, 2005; 12(4): 414 - 422. [Abstract] [Full Text] [PDF]