Protein kinases modulate two glycine currents in salamander retinal ganglion cells.
1. Protein kinase modulation of glycine-activated currents was examined in acutely dissociated ganglion cells from tiger salamander retina using whole-cell voltage-clamp techniques. 2. Glycine (100 microM) induced an outward chloride current in cells clamped at 0 mV. Co-application of 50 microM forskolin made the glycine-induced current more transient. The combination of forskolin and glycine reduced the later portion of current response without changing the initial peak amplitude. 3. 3-Isobutyl-1-methylxanthine (IBMX) or 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) produced effects similar to those of forskolin. H-89, a protein kinase A (PKA) inhibitor, blocked the effect of forskolin. 4. A protein kinase C (PKC) activator, OAG (1-oleoyl-2-acetyl-sn-glycerol), also made the glycine response more transient. Unlike PKA analogues, OAG enhanced the glycine peak response without changing the glycine late response. OAG effects were blocked by 1 microM GF-109203X, a PKC inhibitor. 5. Nanomolar concentrations of strychnine selectively blocked the fast phase of the glycine current and reversed the effect of OAG, but not that of forskolin. Conversely, forskolin occluded the effect of 5,7-dichlorokynurenic acid, which selectively suppresses the late phase of the glycine current. The action of OAG was not blocked by 5,7-dichlorokynurenic acid. 6. Thus, through a differential modulation, both protein kinase A and C shorten the decay time of the glycine current. PKA suppresses the slow component, while PKC potentiates the fast component.
Han
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Departments of Physiology & Biophysics and Ophthalmology, School of Medicine, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY 14214, USA.
Slaughter
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D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000557:Ambystoma; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005998:Glycine / Q000378:metabolism*; D018684:Glycine Agents / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D007736:Kynurenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000201:enzymology*; D013331:Strychnine / Q000494:pharmacology; D013449:Sulfonamides
D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D018684:Glycine Agents; D007546:Isoquinolines; D010726:Phosphodiesterase Inhibitors; D013449:Sulfonamides; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D007736:Kynurenic Acid; D013331:Strychnine; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C066192:5,7-dichlorokynurenic acid; D015056:1-Methyl-3-isobutylxanthine; D005998:Glycine