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 DeVries, S H Articles by Schwartz, E A Search for Related Content PubMed PubMed Citation Articles by DeVries, S H Articles by Schwartz, E A

University of Chicago, IL 60637.

1. Retinas from channel catfish were dissociated and the cells maintained in culture. Horizontal cells that normally receive input from cone photoreceptors were identified. The conductance of the electrical junction formed between a pair of 'cone' horizontal cells was measured by controlling the membrane voltage of each cell with a voltage clamp maintained through either a micropipette or a patch pipette. The two techniques yielded similar results. 2. Transjunctional current was measured while transjunctional voltage was stepped to values between +/- 60 mV. The current (measured 5 ms after a step) was proportional to voltage over the range tested. For steps to voltages greater than +/- 45 mV, the current exhibited a slight time-dependent decline. 3. Dopamine decreased junctional conductance in a dose-dependent fashion. A 50% reduction was obtained with 10 nM-dopamine. The D1 agonist fenoldopam (100 nM) also decreased junctional conductance. The uncoupling produced by either agent was rapid and reversible. 4. The introduction of 100 microM-cyclic AMP into one cell of a pair decreased junctional conductance by, on average, 40%. Forskolin (1-10 microM), an activator of adenylate cyclase, decreased junctional conductance 50-90%. 5. The introduction of 80 microM-cyclic GMP into one cell of a pair decreased junctional conductance by, on average, 40%. Nitroprusside (1-10 microM), an activator of guanylate cyclase, reduced junctional conductance 40-65%. 6. The introduction of a peptide inhibitor specific for the cyclic AMP-dependent protein kinase reversed a decrease in junctional conductance produced by superfusion with either dopamine (1 microM), fenoldopam (100 nM) or forskolin (5-10 microM). 7. Intracellular Ca2+ concentration was measured with the fluorescent indicator Fura-2. The intracellular Ca2+ concentration was increased by activation of a Ca2+ current. Junctional conductance remained constant as the internal Ca2+ concentration changed from 100 to 700 nM. 8. Intracellular pH was measured with the fluorescent indicator bis-carboxyethylcarboxyfluorescein. The application of acetate (2.5 mM) reduced intracellular pH by 0.2-0.3 units and decreased junctional conductance by approximately 50%. A subsequent application of fenoldopam did not alter intracellular pH, but decreased junctional conductance by more than 50%. 9. The sensitivity of the junctional conductance between isolated horizontal cells to dopamine is consistent with dopamine having a direct effect on coupling in intact retina. Dopamine regulates the activity of a cyclic AMP-dependent protein kinase which in turn modulates junctional conductance. Changes in intracellular pH and Ca2+ concentration are not involved in mediating the effect of dopamine on coupling. Cyclic GMP and intracellular pH may participate in regulatory pathways independent of that used by cyclic AMP.

This article has been cited by other articles:

				J. M. Wilson, A. I. Cowan, and R. M. Brownstone Heterogeneous Electrotonic Coupling and Synchronization of Rhythmic Bursting Activity in Mouse Hb9 Interneurons J Neurophysiol, October 1, 2007; 98(4): 2370 - 2381. [Abstract] [Full Text] [PDF]

				M. A. Kreitzer, L. P. Collis, A. J.A. Molina, P. J.S. Smith, and R. P. Malchow Modulation of Extracellular Proton Fluxes from Retinal Horizontal Cells of the Catfish by Depolarization and Glutamate J. Gen. Physiol., July 30, 2007; 130(2): 169 - 182. [Abstract] [Full Text] [PDF]

				M. G. Jonz and S. Barnes Proton modulation of ion channels in isolated horizontal cells of the goldfish retina J. Physiol., June 1, 2007; 581(2): 529 - 541. [Abstract] [Full Text] [PDF]

				J. J. O'Brien, W. Li, F. Pan, J. Keung, J. O'Brien, and S. C. Massey Coupling between A-Type Horizontal Cells Is Mediated by Connexin 50 Gap Junctions in the Rabbit Retina. J. Neurosci., November 8, 2006; 26(45): 11624 - 11636. [Abstract] [Full Text] [PDF]

				J. M. Ackert, S. H. Wu, J. C. Lee, J. Abrams, E. H. Hu, I. Perlman, and S. A. Bloomfield Light-induced changes in spike synchronization between coupled ON direction selective ganglion cells in the mammalian retina. J. Neurosci., April 19, 2006; 26(16): 4206 - 4215. [Abstract] [Full Text] [PDF]

				J. Snellman and S. Nawy cGMP-Dependent Kinase Regulates Response Sensitivity of the Mouse On Bipolar Cell J. Neurosci., July 21, 2004; 24(29): 6621 - 6628. [Abstract] [Full Text] [PDF]

				J. O'Brien, H. B. Nguyen, and S. L. Mills Cone Photoreceptors in Bass Retina Use Two Connexins to Mediate Electrical Coupling J. Neurosci., June 16, 2004; 24(24): 5632 - 5642. [Abstract] [Full Text] [PDF]

				G. Zoidl, R. Bruzzone, S. Weickert, M. Kremer, C. Zoidl, G. Mitropoulou, M. Srinivas, D. C. Spray, and R. Dermietzel Molecular Cloning and Functional Expression of zfCx52.6: A NOVEL CONNEXIN WITH HEMICHANNEL-FORMING PROPERTIES EXPRESSED IN HORIZONTAL CELLS OF THE ZEBRAFISH RETINA J. Biol. Chem., January 23, 2004; 279(4): 2913 - 2921. [Abstract] [Full Text] [PDF]

				E. Garcia-Perez, M. Vargas-Caballero, N. Velazquez-Ulloa, A. Minzoni, and F. F. De-Miguel Synaptic Integration in Electrically Coupled Neurons Biophys. J., January 1, 2004; 86(1): 646 - 655. [Abstract] [Full Text] [PDF]

				G.-Y. Wang, L. C. Liets, and L. M. Chalupa Nitric Oxide Differentially Modulates ON and OFF Responses of Retinal Ganglion Cells J Neurophysiol, August 1, 2003; 90(2): 1304 - 1313. [Abstract] [Full Text] [PDF]

				R. Dermietzel, M. Kremer, G. Paputsoglu, A. Stang, I. M. Skerrett, D. Gomes, M. Srinivas, U. Janssen-Bienhold, R. Weiler, B. J Nicholson, et al. Molecular and Functional Diversity of Neural Connexins in the Retina J. Neurosci., November 15, 2000; 20(22): 8331 - 8343. [Abstract] [Full Text] [PDF]

				D. M. Schneeweis and J. L. Schnapf The Photovoltage of Macaque Cone Photoreceptors: Adaptation, Noise, and Kinetics J. Neurosci., February 15, 1999; 19(4): 1203 - 1216. [Abstract] [Full Text] [PDF]

				D. W. Crevier and M. Meister Synchronous Period-Doubling in Flicker Vision of Salamander and Man J Neurophysiol, April 1, 1998; 79(4): 1869 - 1878. [Abstract] [Full Text] [PDF]

				E. M. Wexler, P. K. Stanton, and S. Nawy Nitric Oxide Depresses GABAA Receptor Function via Coactivation of cGMP-Dependent Kinase and Phosphodiesterase J. Neurosci., April 1, 1998; 18(7): 2342 - 2349. [Abstract] [Full Text] [PDF]

				M. E.M. Kelly and S. Barnes Physiology and Pathophysiology of Nitric Oxide in the Retina Neuroscientist, November 1, 1997; 3(6): 357 - 360. [Abstract] [PDF]

				D.-Q. Zhang and D. G. McMahon Direct gating by retinoic acid of retinal electrical synapses PNAS, December 19, 2000; 97(26): 14754 - 14759. [Abstract] [Full Text] [PDF]