Abstract
Abstract: :
Purpose: To investigate the effects of nitric oxide on the GABA receptor function in the rod bipolar cells of the rat retina. Methods: GABA induced currents were recorded by the whole cell patch clamp method in the rod bipolar cells enzymatically dissociated from retina. After recording, bipolar cells were processed for PKC immunoreactivity. Results: Rod bipolar cells were identified by their morphology and positive immunoreactivity to an antiserum against PKC. GABA (100µM)-activated currents on the rod bipolar cells comprised a fast and sustained part. The fast and the sustained GABA responses were blocked by bicuculline (200 µM; an antagonist of GABAA receptor) and imidazole-4-acetic acid (200 µM; an antagonist of GABAC rceptor), respectively. The GABA responses were completely blocked by picrotoxin (1 mM; a Cl¯ channel blocker). Muscimol (50 µM; an agonist at GABAA receptor) and trans-4-aminocrotonic acid (300 µM; an agonist at GABAC receptor) elicited the current, but baclofen (1 mM; a GABAB receptor agonist) did not minic the GABA effect. Sodium nitroprusside (1mM; a NO donor) reduced the fast part of GABA currents in the rod bipolar cells. The fast responses evoked by muscimol (50 µM) were also reduced in the presence of the NO donor. Conclusion: These results show that NO decrease GABAA receptor function of the rod bipolar cells in the rat retina.
Keywords: 330 bipolar cells • 491 nitric oxide • 541 receptors: pharmacology/physiology