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R W Olsen

Publications and source records attributed to R W Olsen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Expression of the GABA(A) receptor alpha6 subunit in cultured cerebellar granule cells is developmentally regulated by activation of GABA(A) receptors.

Primary cultures of cerebellar granule cells, prepared from cerebella of 7-day-old rats and cultured for 4 or 8 days, were used to study the neurodifferentiative effect of a GABA(A) receptor agonist, 4,5,6,7-tetrahydroisoxazol[5,4-c]pyridin-3-ol (THIP), on the expression of the alpha6 GABA(A) receptor subunit. Membranes prepared from these cultures were photolabeled with the imidazobenzodiazepine [3H]Ro15-4513. In THIP-treated cultures at 4 days in vitro (DIV), photolabeled [3H]Ro15-4513 binding in membranes was significantly increased for both the 51 kilodalton, kDa, (alpha1 subunit) and 56-kDa (alpha6 subunit) radioactive peaks in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In contrast, THIP-treated granule cells at 8 DIV demonstrated a small but significant decrease from control cultures in the photoincorporation of [3H]Ro15-4513 in the 51-kDa peak; however, no significant change in [3H]Ro15-4513 binding was observed for the 56-kDa polypeptide. Immunolabeling of the alpha6 subunit using silver-enhanced, immuno-gold staining of granule cells showed a significant effect with THIP treatment only at 4 DIV and not at 8 DIV. Examination by light microscopy demonstrated that the major effect of THIP was to increase alpha6 subunit clustering on granule cell bodies as well as neurites, 15-fold and sixfold, respectively. Using in situ hybridization, a small THIP-induced increase in alpha6 mRNA was detected at 4 DIV; however, no effect was apparent at 8 DIV. These data suggest that THIP has a trophic effect on alpha6 subunit expression, and this effect occurs only at an early developmental stage. Moreover, this study presents further evidence for the role of GABA(A) agonists, and thus the neurotransmitter, GABA, in regulating the expression of GABA(A) receptor subunits in the developing cerebellum.

Animals↗
PubMed1997

Mice devoid of gamma-aminobutyrate type A receptor beta3 subunit have epilepsy, cleft palate, and hypersensitive behavior.

gamma-Aminobutyric acid type A receptors (GABA(A)-Rs) mediate the bulk of rapid inhibitory synaptic transmission in the central nervous system. The beta3 subunit is an essential component of the GABA(A)-R in many brain regions, especially during development, and is implicated in several pathophysiologic processes. We examined mice harboring a beta3 gene inactivated by gene targeting. GABA(A)-R density is approximately halved in brain of beta3-deficient mice, and GABA(A)-R function is severely impaired. Most beta3-deficient mice die as neonates; some neonatal mortality, but not all, is accompanied by cleft palate. beta3-deficient mice that survive are runted until weaning but achieve normal body size by adulthood, although with reduced life span. These mice are fertile but mothers fail to nurture offspring. Brain morphology is grossly normal, but a number of behaviors are abnormal, consistent with the widespread location of the beta3 subunit. The mice are very hyperactive and hyperresponsive to human contact and other sensory stimuli, and often run continuously in tight circles. When held by the tail, they hold all paws in like a ball, which is frequently a sign of neurological impairment. They have difficulty swimming, walking on grids, and fall off platforms and rotarods, although they do not have a jerky gait. beta3-deficient mice display frequent myoclonus and occasional epileptic seizures, documented by electroencephalographic recording. Hyperactivity, lack of coordination, and seizures are consistent with reduced presynaptic inhibition in spinal cord and impaired inhibition in higher cortical centers and/or pleiotropic developmental defects.

Angelman Syndrome↗
PubMed1997

Chronic intermittent ethanol treatment in rats increases GABA(A) receptor alpha4-subunit expression: possible relevance to alcohol dependence.

Chronic administration of ethanol to rats on an intermittent regimen, for 60 repeated intoxicating doses and repeated withdrawal episodes, results in a long-lasting kindling phenomenon. This involves an increasing severity of withdrawal, including a reduced threshold to seizures produced by the GABA(A) antagonist, pentylenetetrazol. We have shown previously that muscimol-evoked 36Cl- efflux and paired-pulse inhibition (involving GABA(A)-mediated recurrent inhibition) were decreased persistently in the CA1 region of hippocampal slices from chronic intermittent ethanol (CIE)-treated rats. We now report elevated levels of mRNA in forebrain for the alpha4 subunit of the GABA(A) receptor (GABAR), considered to be a constituent of pharmacologically and physiologically novel subtypes of GABARs. Using in situ hybridization with digoxigenin-labeled RNA probes, we show that at 2 days withdrawal, 60-dose CIE leads to a significant 30% increase in alpha4 subunit mRNA levels in the dentate gyrus, 46% increase in the CA3, and 26% increase in the CA1 regions. In contrast, there was no significant change in the mRNAs for the alpha5 subunit or glutamic acid decarboxylase 67 in the same regions. This study suggests that GABAR subunit-selective alterations occur after CIE treatment, possibly resulting in the alteration of the subunit composition of GABARs, with presumably altered physiological functions. This plasticity of GABARs may contribute to the increased withdrawal severity, reduced hippocampal inhibition, and increased seizure susceptibility of this animal model of human alcohol dependence.

Animals↗
PubMed1997

Pentobarbital decreases the gamma-aminobutyric acidA receptor subunit gamma-2 long/short mRNA ratio by a mechanism distinct from receptor occupation.

Treatment with pentobarbital of primary cultured cerebellar granule cells decreased the gamma-aminobutyric acid, (GABA)A receptor subunit gamma-2 long/short (gamma-2L/S) mRNA ratio. A high dose of pentobarbital (500 microM) decreased the gamma-2L/S ratio by 64%; the decrease was dose and time dependent and reversible. (-)-Hexobarbital (500 microM), the less potent stereoisomer for GABA(A) receptor activation, decreased the ratio slightly (30%) but significantly more than (+)-hexobarbital (20%). Other GABA(A) receptor activators had no (100 mM ethanol) or little (2 microM 5alpha-pregnane-3alpha-ol-20-one) effect on the gamma-2L/S ratio. Furthermore, picrotoxin (10 microM), which blocks the GABA- and pentobarbital-activated GABA(A) receptor channel, neither changed the gamma-2L/S ratio nor blocked the pentobarbital-induced changes. These data suggest that barbiturates alter the gamma-2L/S mRNA ratio by a mechanism that does not require GABA(A) receptor activation. The gamma-2L/S subunit mRNA includes an exon encoding an octapeptide that contains a protein kinase C phosphorylation consensus site. This exon-encoded peptide, occurring in the putative intracellular loop, can be phosphorylated, and in vitro, this phosphorylation has been shown to have functional consequences. This is the first report of a drug-induced alteration in receptor mRNA splicing. Furthermore, the changes in the gamma-2L/S ratio produced by pentobarbital exposure may have significant effects on the function of an important brain protein, the GABA(A) receptor.

Animals↗
PubMed1996

Diazepam-insensitive GABAA receptors in rat cerebellum and thalamus.

Three major populations of GABAA receptor binding sites are present in cerebellar membranes: diazepam-sensitive [3H]Ro15-4513 binding sites, diazepam-insensitive [3H]Ro15-4513 binding sites and high-affinity [3H]muscimol binding sites. All three populations contain a beta subunit as shown by immunoprecipitation with antibodies that recognize all beta subunits. The beta 3 subtype of beta subunit is contained in all three populations, but only a similar low fraction (< 20%) in each. Thus, the majority contain beta subunits other than beta 3 (beta 2 and beta 1) and beta 3 subunits are not selectively associated with nor lacking in any of the three binding populations. Antibodies to the gamma 2 subunit precipitated similar fractions of [3H]Ro15-4513, [3H]flunitrazepam and [3H]muscimol binding sites, showing that gamma 2 subunits are present in high-affinity muscimol binding isoforms, as well as a significant fraction of the diazepam-insensitive [3H]Ro15-4513 binding sites. Under conditions that identify the 56 kDa alpha 6 subunit on SDS-PAGE as the diazepam insensitive site of [3H]Ro15-4513 binding in cerebellum, no polypeptide showing diazepam-insensitive binding of [3H]Ro15-4513 could be photoaffinity-labeled in rat thalamus. These results suggest that alpha 4 subunits in the thalamus participate primarily in subunit combinations which bind muscimol but not any benzodiazepine site ligands.

Affinity Labels↗
PubMed1996

Persistent reduction of GABA(A) receptor-mediated inhibition in rat hippocampus after chronic intermittent ethanol treatment.

GABA(A) receptor-mediated function was studied in rats treated with chronic intermittent ethanol (CIE). Rats were given 60 doses of 6g/kg ethanol every 24 h by gastric intubation, with repeated intoxicating and withdrawal episodes leading to a kindling-like increase in seizure susceptibility (Kokka et al., Alcohol: Clin. Exp. Res., 17 (1993) 525-531). Efflux of 36Cl-, evoked by application of muscimol, a measure of GABA(A) receptor function, was examined in 300 mu m slices obtained from frontal, parietal, and temporal cortex, hippocampus, and inferior colliculus, one day after the last administration of ethanol. Compared to controls, the 36Cl- efflux in hippocampal slices of CIE rats was significantly reduced by 29%, while there were no changes in the other brain regions studied. In hippocampal slices, paired-pulse inhibition in CA1 pyramidal neurons, measured extracellularly using homosynaptic orthodromic stimulation at an interval of 10 ms, was significantly reduced in CIE rats. A significant decrease by 40% both at 2 and 40 days after 60 doses of ethanol was found, implying a persistent decrease in GABA(A) receptor-mediated inhibition in CIE rats. These reductions in paired-pulse inhibition are consistent with the decrease in the pentylenetetrazol (PTZ) seizure threshold which was previously observed in CIE rats. Therefore, we suggest that this reduction of GABA(A) receptor-mediated inhibition contributes to the persistent increase in seizure susceptibility of CIE rats.

Animals↗
PubMed1995

Zinc modulation of GABAA receptor-mediated chloride flux in rat hippocampal slices.

We studied the effect of ZnCl2 application on GABAA receptor-mediated 36CI- flux in microsacs prepared from whole rat hippocampus and in region-specific hippocampal slices. Slices were obtained from the dentate gyrus (DG), which contains the zinc-enriched hilar region, and from the CA1 region which contains lower levels of endogenous zinc. Muscimol (10 microM)-evoked 36Cl- flux was significantly reduced by ZnCl2 (100 microM) in hippocampal microsacs. In hippocampal slices, muscimol (50 microM)-evoked 36Cl- efflux was higher in CA1 (112.5 +/- 27.9% above basal efflux rate) than in DG slices (29.7 +/- 5.6%). In the presence of ZnCl2, the muscimol effect on efflux rate in CA1 and DG regions was decreased to 10.6 +/- 5.4% and 6.9 +/- 4.9%, respectively. Preincubation with the zinc chelator, tetrakis(2-pyridylmethyl)ethylenediamine (TPEN, 20 microM), caused a significant increase in muscimol-evoked 36Cl- efflux only in DG slices (57.2 +/- 7.0%), suggesting that GABAA receptors in the DG of rat hippocampus under physiological conditions may function under the inhibitory influence of endogenous chelatable zinc. In intracellular recordings, ZnCl2 (100 microM) application had no effect on the responses to GABA applied perisomatically or in the dendritic region of CA1 neurons. The lack of Zn2+ effect on the postsynaptic GABAA receptor-mediated responses suggests that the decreases of the 36Cl- efflux observed in the biochemical assays may be due to zinc action on neurons other than the principal pyramidal CA1 cells, and possibly the non-neuronal cell populations.

Animals↗
PubMed1995

Length of continuous cocaine exposure determines the persistence of muscarinic and benzodiazepine receptor alterations.

The effects of varied durations of cocaine (1, 3 or 5 days) on muscarinic (MSC) and benzodiazepine (BZD) binding sites in striatum and hippocampus were investigated using homogenate receptor binding. The progressive alterations in these receptor sites from a 5 day cocaine administration were also examined 12 h, 2 days or 21 days after drug exposure. Neither a one nor a three day exposure to cocaine produced any long-term alteration in BZD binding in either structure whereas a 5 day administration produced significant increases in binding. Decreases in MSC receptor binding were apparent in striatum from either a 3 or 5 day cocaine exposure and in hippocampus from a 5 day exposure. The 5 day cocaine exposure produced immediate increases in striatal and hippocampal BZD binding which persisted for 21 days. Conversely, 5 days of cocaine produced a short-term increase in MSC receptor binding in both structures which then became significantly decreased 21 days later. Based on the divergent pattern of changes in BZD and MSC receptor types over time in these structures, it appears that cocaine may induce such changes via separate mechanisms. In addition, it is apparent that changes in the numbers of these receptor sites after cocaine exposure can be quite dynamic, changing rapidly over time.

Analysis of Variance↗
PubMed1995

The gamma-aminobutyric acid receptor gamma 3 subunit gene (GABRG3) is tightly linked to the alpha 5 subunit gene (GABRA5) on human chromosome 15q11-q13 and is transcribed in the same orientation.

GABAA receptors are heterooligomeric ligand-gated ion channels that mediate the effect of the inhibitory neurotransmitter gamma-aminobutyric acid. The GABAA receptors consist of at least 15 different receptor subunits that can be classified into 5 subfamilies (alpha, beta, gamma, delta, rho) on the basis of sequence similarity. Chromosomal mapping studies have revealed that several of the GABAA receptor subunit genes appear to be organized as clusters. One such cluster, which consists of the GABAA receptor beta 3 (GABRB3) and alpha 5 (GABRA5) subunit genes, is located in chromosome 15q11-q13. It is shown here that the GABAA receptor gamma 3 subunit gene (GABRG3) also maps to this region. Lambda and P1 phage clones surrounding both ends of GABRG3 were isolated; the clones derived from the 5' end of GABRG3 were linked to an existing phage contig spanning the 3' end of GABRA5. The two genes are located within 35 kb of each other and are transcribed in the same orientation.

Animals↗
PubMed1995

Modulation of GABAA receptor binding in human brain by neuroactive steroids: species and brain regional differences.

Allosteric modulation by neuroactive steroids of radioligand binding sites on the GABAA receptor complex was demonstrated by autoradiography in vitro in several regions of human brain and the effects compared to those in rat brain. Comparing human and rat, two steroids known to be active in enhancing GABA-mediated postsynaptic inhibition, 5 alpha-pregnane-3 alpha,21-diol-20-one (tetrahydro-deoxycorticosterone, THDOC) and alphaxalone (5 alpha-pregnane-3 alpha-hydroxy-11,20-dione), allosterically inhibited [35S]T-BPS binding to the picrotoxin/convulsant site in both species in several regions including the hippocampus. Unlike rat, human brain binding of [3H]flunitrazepam to the benzodiazepine site was not enhanced by alphaxalone (at any concentration), but was unaffected in many regions and inhibited in others. Binding of [3H]muscimol to high and low affinity GABA sites were enhanced by both steroids in all tested regions of rat brain, although to varying degrees. However, several lobes of human cortex showed no modulation of muscimol binding by either steroid, and THDOC, but not alphaxalone, inhibited in some areas. Comparing regions, THDOC at high concentrations (10 microM) enhanced in human frontal lobe and primary sensory and motor cortex, with greater effect in deep layers than superficial. This steroid had no effect in other parts of parietal lobe and inhibited muscimol binding in temporal lobe, primary visual cortex, and other parts of occipital lobe. Concentration-dependence curves for THDOC showed regional variation, e.g., in the hippocampal formation and surrounding neocortex. These regional and species differences are consistent with the existence of multiple GABAA receptor subtypes that differ in pharmacology. This heterogeneity provides both the opportunity and the difficulty of targeting clinically useful medications such as antiepileptic drugs to the appropriate human brain regions, and the species differences in regional subtype expression suggest caution in use of animal models.

Autoradiography↗
PubMed1995

Tyrosine kinase phosphorylation of GABAA receptors.

Phosphorylation of purified bovine brain GABAA receptors by the tyrosine kinase, pp60v-src was examined. pp60v-src phosphorylated two bands of 54-62 kDa and 48-51 kDa that migrated to approximately the same position as bands recognized by antisera against the beta 2 and gamma 2 GABAA receptor subunits, respectively. Bacterially expressed proteins containing the putative large cytoplasmic loops of the beta 1 and gamma 2L subunits were phosphorylated by pp60v-src, indicating that the phosphorylation sites are located in these subunit domains. The tyrosine kinase inhibitors, genistein and the tyrphostins B-42 and B-44, inhibited muscimol-stimulated 36Cl- uptake in mouse brain membrane vesicles (microsacs). magnitude of the tyrphostin B-44-induced inhibition of muscimol-stimulated 36Cl- uptake was significantly reduced in microsacs that were lysed and resealed under conditions that inhibit phosphorylation. GABA-gated Cl- currents were also inhibited by genistein and tyrphostin B-44 in Xenopus oocytes expressing alpha 1 beta 1 and alpha 1 beta 1 gamma 2L subunits. Consequently, protein tyrosine kinase-dependent phosphorylation appears to be another mechanism of regulating the function of GABAA receptors.

Animals↗
PubMed1995

Functional domains of GABAA receptors.

The transmitter-gated ion channels mediate rapid synaptic transmission, for example, at the neuromuscular junction using acetylcholine and in the CNS using primarily the amino acids glutamate and GABA. GABAA-receptor Cl- channels share sequence homology with a superfamily of these channels including nicotinic acetylcholine receptor and inhibitory glycine receptor. In this article, Geoffrey Smith and Richard Olsen discuss recent affinity labelling and site-directed mutagenesis studies on GABAA receptors that have identified amino acid residues essential for binding of agonists and allosteric modulators as well as the ion channel wall formation. The structural domains identified are consistent with results obtained with other members of the transmitter-gated ion channel superfamily and suggest that structural models for one member of the family may apply to the others as well.

Amino Acid Sequence↗
PubMed1995

Pharmacological subtypes of the gamma-aminobutyric acidA receptors defined by a gamma-aminobutyric acid analogue 4,5,6,7-tetrahydroisoxazolo[5,4-c] pyridin-3-ol and allosteric coupling: characterization using subunit-specific antibodies.

Various alpha and beta 3 subunit-specific antibodies were used to characterize some of the heterogeneous ligand-binding properties of gamma-aminobutyric acidA receptors. Polyclonal antibodies that were raised against the cytoplasmic amino acid sequence (380-392) of the rat beta 3 subunit recognized a single polypeptide of molecular mass of 58 kDa in Western blots with Ro7-1986 affinity-purified GABAA receptors from the rat brain, and a doublet of molecular mass of 54 kDa and 56 kDa in receptors from the bovine cortex, hippocampus, and cerebellum. Deglycosylation of purified receptors from the bovine cortex with N-glycanase resulted in a single band immunostained at molecular mass of 52 kDa. These anti-beta 3 subunit antibodies immunoprecipitated approximately 50% of [3H]flunitrazepam binding sites from soluble extracts of bovine cortex, whereas beta cyto antibodies, which probably recognize all beta subunit isoforms, precipitated almost 100% of benzodiazepine binding sites. These results indicate heterogeneity of GABAA receptor subunit composition with respect to the nature of beta subunits. The GABA analogue 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), like GABA, shows heterogeneous binding affinities in brain homogenates. The higher affinity sites were previously suggested as corresponding to a 58-kDa polypeptide in rat that is photoaffinity-labeled with [3H]muscimol, a band that comigrates with the one stained by anti-beta 3 antibodies. However, THIP affinity was not significantly different between receptors containing beta 3 subunits and those lacking beta 3, as demonstrated by similar affinities in receptors that ere immunoprecipitated by anti-beta 3 antibodies and those that were not. Also, THIP displaced [3H]muscimol binding with similar multiple affinities across brain regions where different beta subunit variants are expressed with varying abundances. These observations suggest that the property of high affinity THIP binding cannot be explained solely by beta 3 subunits. The coupling efficiency between GABA and benzodiazepine binding sites appears to be determined by the nature of alpha subunits rather than of beta subunits. GABA enhanced [3H]flunitrazepam binding with different efficacies and potencies in receptors immunoprecipitated by anti-alpha 1, -alpha 2, and -alpha 3 subunit antibodies. In contrast, beta 3 subunit-enriched and disenriched receptors did not differ in this property. [3H]Flunitrazepam binding in GABAA receptors containing alpha 2 and alpha 3 subunits was enhanced to a significantly greater extent than were those with alpha 1. In addition, receptors containing alpha 1 and alpha 3 subunits had higher potencies of enhancement than did those with alpha 2 subunits.(ABSTRACT TRUNCATED AT 400 WORDS)

Allosteric Regulation↗
PubMed1995

Neuroactive steroid modulation of GABAA receptors.

In summary, the discovery of neuroactive steroids has led to a new appreciation of endocrine-nervous system interactions. The modulation of GABAA receptors by steroid hormone metabolites has far-reaching physiological and pharmacological implications, including relevance to human psychiatric and neurological problems (Fig. 7): I. MECHANISM OF GENERAL ANESTHESIA (Alphaxalone) II. GABA TONE IN SOME REGIONS (e.g., caudate) III. ANTI-ANXIETY ACTIVITY: (Post-partum depression, premenstrual syndrome?) (New drugs?) IV. CHILDBIRTH V. ANTIEPILEPTIC ACTIVITY (New drugs?) VI. REGIONAL HETEROGENEITY (Receptor subtypes) VII. PARTIAL AGONISTS (Better clinical profile?) FIG. 7. Implications of GABAA receptor as a nongenomic CNS target of steroids.

Animals↗
PubMed1994

Identification of a [3H]muscimol photoaffinity substrate in the bovine gamma-aminobutyric acidA receptor alpha subunit.

An amino acid which appears to be involved in an agonist binding site of the gamma-aminobutyric acid type A (GABAA) receptor protein has been identified by photoaffinity labeling of affinity purified bovine receptor with [3H]muscimol and microsequencing of a chymotryptic fragment. Sequencing of a major purified labeled peptide gave the sequence Thr-Ile-Asp-Val-Phe with release of 3H label in the fifth cycle, corresponding to Phe. These 5 residues match the published sequence for the bovine alpha 1 subunit beginning at Thr61, following the chymotryptic substrate Tyr60. This sequence is found in the alpha 1-3 subunits of rat and cow and alpha 5 of rat, but not in any beta. Although previous evidence tentatively suggested that the beta subunit was the major [3H]muscimol-labeled subunit, homomeric expression studies have shown the potential for a functional gamma-aminobutyric acid binding site on all classes of subunits. The residue carrying the label, Phe65 on alpha 1, is conserved among all GABAA receptor alpha subunits, gamma 2, and delta. In addition, recent data indicated that a point mutation of Phe64-->Leu in rat alpha 1 subunit strongly decreased agonist and antagonist affinity when coexpressed with beta 2 and gamma 2 subunits in Xenopus oocytes (Sigel, E., Baur, R., Kellenberger; S., and Malherbe, P. (1992) EMBO J. 11, 2017-2023). The photolabeled Phe residue identified in this report is the bovine homolog to the Phe64 identified by the mutation studies of Sigel et al., to affect function in the rat GABAA receptor.

Affinity Labels↗
PubMed1994

Distinctive patterns of GABAA receptor subunit mRNAs in 13 cell lines.

We have investigated the GABAA receptor mRNA composition in 13 cell lines, using 13 subunit-specific oligo-primers (alpha 1-6, beta 1-3, gamma 1-3, and delta) and reverse transcriptase PCR amplification. Cell lines (B35, B65, B103, B104, RINm5F, Rat1, PC12, C6, C17, C27, beta TC3, NB41A3, AtT-20), derived from diverse tissue origins, were investigated in order to identify homogeneous cellular sources with distinctive GABAA receptor subunits. Fifteen GABAA receptor subunits have been cloned from mammalian tissue (those listed above plus the retinal subunits rho 1 and rho 2). This multiplicity of GABAA receptor subunits underlies the diverse pharmacology of the GABAA receptor. Attempts to understand the regulation and pharmacology of individual subunits and of the heterooligomeric receptor combinations have been impeded by a lack of pure populations of cells expressing GABAA receptor subunits. Permanent cell lines provide such a resource. Each GABAA receptor subunit mRNA, alpha 1-5, beta 1-3, gamma 1-3, and delta, was detected in at least one cell line. All cell lines examined contained detectable levels of at least one GABAA receptor subunit mRNA. Each cell line contained distinctive combinations of subunit mRNAs. None of the cell lines examined contained detectable amounts of alpha 6 mRNA. These cell lines, which transcribe GABAA receptor subunit mRNAs, provide useful cellular sources for transcriptional and pharmacological studies. Our data also suggest that endogenous GABAA receptor subunit mRNAs may be present in cells that are routinely used for transfection studies, and that this expression might confound interpretation of the studies. In the following companion article, we have looked for functional GABAA receptor Cl- ion channels in these cell lines, using the patch-clamp technique (Hales and Tyndale, 1994).

Animals↗