a1 Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Winston-Salem
Using patch-clamp recording in combination with reverse transcriptase-polymerase chain reaction (RT-PCR), we show in individual bipolar cells acutely dissociated from the adult rat retina a correlation between the expression of the GABAA receptor ρ1 subunit mRNA and a bicuculline-resistant, diazepam-insensitive component of the GABA-activated whole-cell current response. This “GABAC-like” response, contributing to approximately 42% of the GABA-activated whole-cell current and displaying variable sensitivity to picrotoxin, was found in bipolar cells but not in any of the ganglion cells examined. Expression profiling of GABAA receptor subunit mRNAs in individual electrophysiologically tested retinal neurons revealed that, while both bipolar cells and ganglion cells may express numerous GABAA receptor subunit isoforms, including that of ρ2, the expression of the ρ1 subunit was strictly limited to bipolar cells. We propose a possible link between the presence of a receptor with GABAC-like pharmacological profile and the expression of the retina-specific ρ1 subunit isoform. The results presented in this study constitute the first direct demonstration of such a correlation at the single-cell level.
(Received March 28 1995)
(Accepted July 24 1995)
Reprint requests to present address of Hermes H. Yeh: Department of Pharmacology, The University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-6125, USA.