Effects of benzodiazepines on frog ERG.
Effect of flurazepam (water-soluble benzodiazepine) on the amplitude and time course of ERG waves was investigated in superfused frog eyecups (Rana ridibunda). Flurazepam (50 and 100 microM) had inhibitory effect on the b- and d-wave amplitude, which was not accompanied with significant changes in their implicit time. Flurazepam potentiated the depressant effect of GABA (2.5 and 5 mM) on the b- and d-wave amplitude. The inhibitory effect of flurazepam was not blocked by 50 microM bicuculline (BCC), (GABA(A) antagonist), although the blocker markedly potentiated the b- and d-wave amplitude. The suppressive effect of flurazepam on the b- but not d-wave amplitude was blocked by 100 microM BCC. Our results indicate existence of functional benzodiazepine regulatory sites on GABA(A) receptors in distal frog retina.
Popova
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Department of Physiology, Medical Faculty, Medical University, 1431 Sofia, Bulgaria. popova@medfac.acad.bg
D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology*; D001640:Bicuculline / Q000494:pharmacology; D004596:Electroretinography / Q000187:drug effects* / Q000379:methods; D005479:Flurazepam / Q000494:pharmacology; D066298:In Vitro Techniques; D011895:Rana ridibunda; D012160:Retina / Q000187:drug effects* / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D001569:Benzodiazepines; D005680:gamma-Aminobutyric Acid; D005479:Flurazepam; D001640:Bicuculline