QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, May 4, 2005, 25(18):4633-4640; doi:10.1523/JNEUROSCI.4298-04.2005

This Article Full Text Full Text (PDF) A correction has been published Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted 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 (22) Citing Articles via Google Scholar Google Scholar Articles by Rabl, K. Articles by Thoreson, W. B. Search for Related Content PubMed PubMed Citation Articles by Rabl, K. Articles by Thoreson, W. B.

 Previous Article  |  Next Article 

Cellular/Molecular
Kinetics of Exocytosis Is Faster in Cones Than in Rods

Katalin Rabl,¹ Lucia Cadetti,¹ and Wallace B. Thoreson^1,2

Departments of ¹Ophthalmology and Visual Sciences and ²Pharmacology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5840

Cone-driven responses of second-order retinal neurons are considerably faster than rod-driven responses. We examined whether differences in the kinetics of synaptic transmitter release from rods and cones may contribute to differences in postsynaptic response kinetics. Exocytosis from rods and cones was triggered by membrane depolarization and monitored in two ways: (1) by measuring EPSCs evoked in second-order neurons by depolarizing steps applied to presynaptic rods or cones during simultaneous paired whole-cell recordings or (2) by direct measurements of exocytotic increases in membrane capacitance. The kinetics of release was assessed by varying the length of the depolarizing test step. Both measures of release revealed two kinetic components to the increase in exocytosis as a function of the duration of a step depolarization. In addition to slow sustained components in both cell types, the initial fast component of exocytosis had a time constant of <5 ms in cones, >10-fold faster than that of rods. Rod/cone differences in the kinetics of release were substantiated by a linear correlation between depolarization-evoked capacitance increases and EPSC charge transfer. Experiments on isolated rods indicate that the slower kinetics of exocytosis from rods was not a result of rod-rod coupling. The initial rapid release of vesicles from cones can shape the postsynaptic response and may contribute to the faster responses of cone-driven cells observed at light offset.

Key words: ribbon synapse; capacitance measurement; retina; tiger salamander; photoreceptor; postsynaptic current

---

Received Oct 20, 2004; revised April 4, 2005; accepted April 5, 2005.

This article has been cited by other articles:

				D. Dulon, S. Safieddine, S. M. Jones, and C. Petit Otoferlin Is Critical for a Highly Sensitive and Linear Calcium-Dependent Exocytosis at Vestibular Hair Cell Ribbon Synapses J. Neurosci., August 26, 2009; 29(34): 10474 - 10487. [Abstract] [Full Text] [PDF]

				J.-J. Pang, F. Gao, A. Barrow, R. A. Jacoby, and S. M. Wu How do tonic glutamatergic synapses evade receptor desensitization? J. Physiol., June 15, 2008; 586(12): 2889 - 2902. [Abstract] [Full Text] [PDF]

				W. B. Thoreson, N. Babai, and T. M. Bartoletti Feedback from Horizontal Cells to Rod Photoreceptors in Vertebrate Retina J. Neurosci., May 28, 2008; 28(22): 5691 - 5695. [Abstract] [Full Text] [PDF]

				B. Innocenti and R. Heidelberger Mechanisms Contributing to Tonic Release at the Cone Photoreceptor Ribbon Synapse J Neurophysiol, January 1, 2008; 99(1): 25 - 36. [Abstract] [Full Text] [PDF]

				R. Heidelberger Mechanisms of tonic, graded release: lessons from the vertebrate photoreceptor J. Physiol., December 15, 2007; 585(3): 663 - 667. [Abstract] [Full Text] [PDF]

				A. Molnar and F. Werblin Inhibitory Feedback Shapes Bipolar Cell Responses in the Rabbit Retina J Neurophysiol, December 1, 2007; 98(6): 3423 - 3435. [Abstract] [Full Text] [PDF]

				Z. Sheng, S.-Y. Choi, A. Dharia, J. Li, P. Sterling, and R. H. Kramer Synaptic Ca2+ in Darkness Is Lower in Rods than Cones, Causing Slower Tonic Release of Vesicles J. Neurosci., May 9, 2007; 27(19): 5033 - 5042. [Abstract] [Full Text] [PDF]

				L. Cadetti and W. B. Thoreson Feedback Effects of Horizontal Cell Membrane Potential on Cone Calcium Currents Studied With Simultaneous Recordings J Neurophysiol, March 1, 2006; 95(3): 1992 - 1995. [Abstract] [Full Text] [PDF]

				K. Rabl, L. Cadetti, and W. B. Thoreson Paired-Pulse Depression at Photoreceptor Synapses J. Neurosci., March 1, 2006; 26(9): 2555 - 2563. [Abstract] [Full Text] [PDF]

				L. Cadetti, D. Tranchina, and W. B. Thoreson A comparison of release kinetics and glutamate receptor properties in shaping rod-cone differences in EPSC kinetics in the salamander retina J. Physiol., December 15, 2005; 569(3): 773 - 788. [Abstract] [Full Text] [PDF]

				K. Reim, H. Wegmeyer, J. H. Brandstatter, M. Xue, C. Rosenmund, T. Dresbach, K. Hofmann, and N. Brose Structurally and functionally unique complexins at retinal ribbon synapses J. Cell Biol., May 23, 2005; 169(4): 669 - 680. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help