Furosemide increases the basal tert-[³⁵S]butylbicyclophosphorothionate
([³⁵S]TBPS) binding and reverses the inhibition of the binding by
gamma-aminobutyric acid (GABA) in the cerebellar GABA_A receptors
containing the alpha6 and beta2/beta3 subunits. These effects are less
pronounced in the alcohol-sensitive (ANT) than in the
alcohol-insensitive (AT) rat line. The difference between the rat lines
in the increase of basal [³⁵S]TBPS binding was removed after a longer
preincubation with ethylendiaminetetraacetic acid (EDTA) containing
buffer, but long preincubation did not reduce the GABA content of the
incubation fluid or remove the difference in GABA antagonism by
furosemide. The GABA sensitivity of the [³⁵S]TBPS binding did not differ
between the rat lines. There was no nucleotide sequence difference in
the beta2 or beta3 subunits between the rat lines and similar beta2/3
subunit-dependent agonistic actions by
methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) in the
rat lines were detected. The data suggest that there are still unknown
structural alterations in the cerebellar GABA_A receptors between the
AT and ANT rat lines, possibly associated with differential alcohol
sensitivity.