The relationship between light, dopamine release and horizontal cell coupling in the mudpuppy retina.

Dopamine concentrations of 10-250 microM may decrease electrical coupling between horizontal cells in the mudpuppy retina.

• An increase in response amplitude to a centered spot stimulus and a decrease in response to a concentric annulus indicate changes in coupling between horizontal cells.
• Dopamine's effect on coupling is significantly more pronounced in dark-adapted retinas compared to light-adapted retinas.
• The D1-receptor agonist SKF38393 mimics the uncoupling effect of dopamine, while the D2-receptor agonist LY171555 produces the opposite effect.
• The D1 antagonist SCH23390 leads to increased coupling, especially in light-adapted conditions.
• Exposure to the glutamate analogue APB increases coupling between horizontal cells more in light-adapted retinas and may decrease dopamine release.
• Adaptation to light for 2.5 minutes reduces horizontal cell coupling, an effect that can be blocked by SCH23390 or APB.

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