Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at square root of sNN=200 GeV

We present STAR measurements of the azimuthal anisotropy parameter v(2) and the binary-collision scaled centrality ratio R(CP) for kaons and lambdas (Lambda+Lambda) at midrapidity in Au+Au collisions at square root of s(NN)=200 GeV. In combination, the v(2) and R(CP) particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p(T) approximately 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K(0)(S) and Lambda+Lambda v(2) values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination.

A distance of 133–137 parsecs to the Pleiades star cluster

Nearby 'open' clusters of stars (those that are not gravitationally bound) have played a crucial role in the development of stellar astronomy because, as a consequence of the stars having a common age, they provide excellent natural laboratories to test theoretical stellar models. Clusters also play a fundamental part in determining distance scales. The satellite Hipparcos surprisingly found that an extensively studied open cluster--the Pleiades (also known as the Seven Sisters)--had a distance of D = 118 +/- 4 pc (refs 2, 3), about ten per cent smaller than the accepted value. The discrepancy generated a spirited debate because the implication was that either current stellar models were incorrect by a surprising amount or Hipparcos was giving incorrect distances. Here we report the orbital parameters of the bright double star Atlas in the Pleiades, using long-baseline optical/infrared interferometry. From the data we derive a firm lower bound of D > 127 pc, with the most likely range being 133 < D < 137 pc. Our result reaffirms the fidelity of current stellar models.

Pion-Kaon correlations in central Au+Au collisions at square root [sNN] = 130 GeV

Pion-kaon correlation functions are constructed from central Au+Au STAR data taken at sqrt[s(NN)]=130 GeV by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e., transverse flow, lead to a space-time emission asymmetry of pions and kaons that is consistent with the data. This result provides new independent evidence that the system created at RHIC undergoes a collective transverse expansion.

Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5<p(T)<12 GeV/c. The collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.

Evidence from d+Au measurements for final-state suppression of high-p(T) hadrons in Au+Au collisions at RHIC

We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions.

A recombinant fusion protein and DNA vaccines against foot-and-mouth disease virus type Asia 1 infection in guinea pigs

On the basis of amino acid (aa) sequence of the tandem repeat 133-158-20-34-133-158 which consisted of aa 133-158 of VP1 and aa 20-34 of VP4 of Foot-and-mouth disease virus (FMDV) type Asia 1 a recombinant prokaryotic expression vector pAS1-P encoding a fusion protein and eukaryotic expression vectors pAS1-E and pAS1-EdeltaCpG-ODN representing DNA vaccines were constructed. Guinea pigs immunized with these vaccines showed both neutralizing antibody and T cell proliferation responses. FMDV challenge tests for the first time showed that the recombinant fusion protein and pAS1-E and pAS1-EdeltaCpG-ODN vaccines protected 86%, 60% and 43% of guinea pigs from FMDV type Asia1 challenge, respectively. The results also indicated that the immune response of animals treated with the vector pAS1-E containing an oligodeoxynucleotide (ODN), which consisted of immunostimulatory cytosine-phosphate-guanosine (CpG) motifs, was augmented by CpG ODN.

[Association between dopamine transporter gene polymorphism and Parkinson's disease]

OBJECTIVE

To detect the association between dopamine transporter gene polymorphism and Parkinson's disease (PD).

METHODS

The authors analyzed the difference in the distribution of the variable number tandem repeat (VNTR ) polymorphism within the 3' untranslated region of the DAT gene between 85 normal controls and 128 PD patients that were further divided into the senile subgroup (aged >50 years at onset of PD ) and the early-onset subgroup (aged </=50 years).

RESULTS

There were significant differences in genotypic and allelic distribution between the control group and the PD group. The senile PD was strongly associated with the 7-copy allele and weakly with the 10-copy allele, and the early onset PD was mainly associated with the 9-copy allele.

CONCLUSION

The findings not only support an association between DAT gene and PD but also suggest the relationship of the 3'VNTR polymorphism of DAT gene with the age at the onset of PD.

[Induced tolerance to cardiac allografts with intrathymic injection of donor spleen cells]

OBJECTIVE

To study the methods and mechanisms of immune tolerance in cardiac transplantation.

METHODS

Male DA rat hearts were transplanted to male Lewis rats using Ono's model and randomly divided into four groups: untreated (group I), intrathymic injection of 2.5 x 10(7) DA splenocytes to Lewis rat (group II), intraperitoneal injection of 1 ml rabbit anti-rat lymphocyte serum (ALS) to Lewis recipient (group III), intrathymic injection of 2.5 x 10(7) DA splenocytes combined with intraperitoneal injection of 1 ml rabbit anti-rat lymphocyte serum (ALS) to Lewis recipient (group IV). 21 days later heart transplantation was performed. Mean survival time (MST), histological changes and mixed lymphocyte reaction (MLR) were measured after operation.

RESULTS

In the group of intrathymic injection of spleen cells combined with ALS treatment, the survival time of heart allografts [MST: (81.8 +/- 7.6)d] was significantly longer than in the groups I [MST: (7.3 +/- 1.0) d], group II [MST:(7.8+/- 1.0)d], and group III [MST(8.2 +/- 1.2) d, P < 0.01]. Only a few inflammatory cells infiltrated in cardiac allografts in group IV. MLR of group IV were significantly decreased compared with those of the normal control (P < 0.01).

CONCLUSIONS

The role of thymus as a special site for induction and maintenance of specific immunological unresponsiveness to organ allografts was confirmed. T cell clonal deletion may play an important role in this immune tolerance.

[Effects of seed coating formulation on seedling characters of Atractylodes macrocephala]

The effects of seed coating formulation (SCF) of Atractylodes macrocephala Koidz. on seedling in two experimental plots located in Hangzhou and Jiande were studied, and desinged with L9(3(4)) orthogonal comparison. The results showed that the SCF with paclobutrazol (pp333) had a significant effect on the rate of germination at Hangzhou plot, all factors had no significant effects on length of seedlings in both plots, and both atonik (sodium O-nitrophenolate) and PP333 on the fresh or dry seedling weight had significant effects.

[Enrichment of organic matter and nitrogen in eroded bedloads]

Under natural rainfall, the influences of rainfall, slope gradient, tillage and fertilization on the enrichment ratio(ER) of organic matter(OM) and total nitrogen(TN) in eroded bedloads and the relationship between the ER and the composition of eroded bedloads was analyzed. The results showed that the enrichment of clay(ERclay) resulted in the enrichment of OM and TN, and the average value of ERclay, EROM and ERTN under different slope gradients was 1.77, 2.09 and 1.61, respectively. The soil erosion module was negatively correlated with EROM and ERTN. The measures for soil erosion may increase the EROM and ERTN affected by rainfall, slope gradient, tillage and fertilization.

[Genetic polymorphisms of cytochrome P450 1A1 and susceptibility of early-onset Parkinson's disease]

OBJECTIVE

To assess the possible association between the Msp I polymorphisms of cytochrome P450 1A1(CYP1A1) and the susceptibility of early-onset Parkinson's disease among Hans in the northern part of China.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to analyze three genotypes A, B and C in 3'flanking region of CYP1A1 in 126 patients with idiopathic early-onset Parkinson's disease and 172 healthy controls.

RESULTS

The frequencies of genotypes A, B and C in patients were 41.3%, 43.6% and 15.1% while those in the controls were 34.9%, 51.7% and 13.4%, respectively. No statistically significant difference in the frequencies of the three genotypes was observed between the two groups. The frequencies of two alleles were of no significant difference between the patients and controls.

CONCLUSION

The above results suggest that the Msp I polymorphisms of cytochrome P450 1A1 itself might not be associated with idiopathic early-onset Parkinson's disease.

Regional glucose metabolic increases in left auditory cortex in tinnitus patients: a preliminary study with positron emission tomography

OBJECTIVE

To investigate the relationship between tinnitus and glucose metabolism in auditory cortex and whether positron emission tomography (PET) can be an objective tool in measuring tinnitus.

METHODS

Eleven right-handed patients with severe tinnitus and ten right-handed control subjects participated in the 18F-FDG/PET study. Analysis with regions of interests was used to calculate asymmetry indices according to the formula: [(L-R) x 100/[(L + R) divided by 2]].

RESULTS

Glucose metabolism in the auditory cortex of tinnitus patients was asymmetric between the left and right auditory cortices, with that of the left being much higher than that of the right. The asymmetry indices of tinnitus patients was significantly higher than that of the control group (unpaired t test, P < 0.001). This revealed that the increased metabolic activity was present in the predominant left hemisphere with a significant focus on the superior and transverse temporal gyri (Brodmann areas 41 and 42, respectively corresponding to primary and secondary auditory cortex), and the results were independent of the subjective localization of the tinnitus sensation.

CONCLUSION

It is suggested that the increased metabolism in the left auditory cortex is related to the tinnitus sensation. PET is capable of providing objective evidence for tinnitus and may be used as a potential tool in measuring tinnitus.

Influence of fuel quality on vehicular NOx emissions

The quality of gasoline and diesel fuel affects pollutant emissions from vehicles. By applying the COMPLEX model, developed by the US EPA and industry to relate fuel composition to vehicle emissions, this paper estimates the influence of improvements in gasoline quality to lower vehicular NOx emissions. A case study is performed for Guangzhou City that has NOx concentrations significantly above the national ambient air quality standards(NAAQS). The paper discusses the potential for reducing NOx in Guangzhou by improving the quality of gasoline.

[High concentration ethanol continuous fermentation using yeast flocs]

Continuous ethanol fermentation using yeast flocs was carried out in 4 air-lift suspended-bed bioreactors operated in series. Drafted by CO2, with complete recycle of ethanol distilled effluent broth and at the dilution rate of 0.2/h, the average ethanol concentration of the fermentation broth was 96.6 g/L, while the average concentration of residual total sugar was 4.1 g/L and residual reducing sugar was 1.2 g/L.

[Polymorphism of MAO-B gene and NAD(P)H: quinone oxidoreductase gene in Parkinson's disease]

OBJECTIVE

To investigate whether Parkinson's disease(PD) is associated with genetic polymorphism of intron 13 of monoamine oxidase B(MAO-B) and NAD(P)H: quinone oxidoreductase(NQO1) gene cDNA 609C to T.

METHODS

Association study was performed in 126 PD patients and 136 healthy control subjects matched for age, sex and origin. The NQO1 gene polymorphism was analyzed with the polymerase chain reaction-restriction fragment length polymorphism, the polymorphism of intron 13 of MAO-B was analyzed by allele- specific PCR.

RESULTS

The allelic frequency of the mutant T allele of NQO1 gene was significantly higher in the PD patients as compared to the controls(P<0.05). The relative risk of suffering from PD increased (OR=3.8) in the individuals with T allelic genotype of NQO1 gene, and the odds ratio was as high as 5.7 when the individuals with A or AA genotype of MAO-B gene coexisted with the T allele genotype of NQO1 gene.

CONCLUSION

The cDNA 609T allele of NQO1 gene might be a risk factor of PD, which could be associated with the genetic susceptibility of PD. The high activity A or AA genotype of MAO-B and the low activity genotype of NQO1 gene might have synergistic effect. When both genotypes coexist, the risk of suffering PD will be increased greatly.

Preliminary studies on parkin gene deletion at exons 1 to 6 in Chinese patients with praecox Parkinson's disease

OBJECTIVE

To search parkin gene deletion mutations at exons 1 to 6 in Chinese patients with praecox Parkinson's disease (PPD) and analyze them together with the clinical features of PPD.

METHODS

DNA was extracted from peripheral blood of PPD patients; deletion mutations of parkin gene were identified by PCR amplification and agarose gel electrophoresis. The clinical data were analyzed together with the above information.

RESULTS

Out of 21 patients, 2 had exon 1 deletion, 2 exon 4 deletion, and 1 exon 6 deletion. The mean age of the patients with deletion mutation was 45.7+/-1.8 years. All of the patients who had parkin gene deletion mutation had tremor, rigidity and bradykinesia, but athetosis and family history of PD were not found. In additon, the deletion mutations of parkin gene at exons 2, 3, 5, were not found.

CONCLUSION

There are deletion mutations of parkin gene at exons 1,4,6 in PPD of Chinese, and such deletions generally happen on middle-aged patients.

[Modulation of GABA-activated currents by oxytocin in rat dorsal root ganglion neurons]

Experiments were performed on freshly isolated dorsal root ganglion (DRG) neurons of rat. GABA(A)-activated currents were recorded using the whole-cell patch clamp technique. The majority of the neurons (48/52, 90.5%) were sensitive to GABA (10( 6)~10( 3) mol/L). Application of oxytocin (OT) induced outward membrane responses in 51.3% (20/39) of the neurons, no apparent responses in 43.6% (17/39) and inward responses in 5.1% (2/39). 10( 12), 10( 11), 10( 10) and 10( 9) mol/L OT increased 10( 4) mol/L GABA-activated currents to 24.1+/-7.6% (n=6), 33.4+/-6.9% (n=9), 40.2+/-6.5% (n=13) and 67.2+/-14.8% (n=5), respectively. After preapplication of OT, the Kd value for GABA(A)-activated currents decreased, while the response obtained at the maximum concentration increased. The results suggest that the enhancement of GABA-activated currents by OT may suppress primary sensory transmission by potentiating pre-synaptic inhibition of GABA.

Mouse keratinocytes immortalized with large T antigen acquire alpha3beta1 integrin-dependent secretion of MMP-9/gelatinase B

Remodeling of the extracellular matrix during tissue development, wound repair and tumor cell invasion depends on the coordinated regulation of cell adhesion receptors, matrix proteins and enzymes that proteolyse the extracellular matrix. Integrin alpha3beta1 is a major receptor on epidermal keratinocytes for laminin-5 in the cutaneous basement membrane and is required for normal basement membrane organization during skin development. alpha3beta1 is also expressed at high levels in the majority of adherent transformed cells and in most tumors, and it could have similar roles in extracellular matrix remodeling during tumorigenesis and cell invasion. In the present study, we show that alpha3beta1 expression is required in immortalized mouse keratinocytes (MK) for the production of the matrix metalloproteinase MMP-9/gelatinase B, an MMP that is coexpressed with alpha3beta1 in epithelial cell carcinomas and during wound healing, and contributes to the invasive potential of some tumor cells. MMP-9 was expressed in MK cells derived from wild-type mice, but not in MK cells derived from alpha3-null mice. Reconstitution of alpha3beta1 expression in alpha3-null MK cells through transfection with the alpha3 subunit restored MMP-9 secretion, indicating an alpha3beta1-dependent pathway for MMP-9 production. alpha3beta1-dependent expression of MMP-9 was associated with the immortalized phenotype, since nonimmortalized, primary keratinocytes required soluble growth factors, but not alpha3beta1, for efficient expression of MMP-9. Our results suggest that an alpha3beta1-independent pathway(s) for MMP-9 production is suppressed in keratinocytes immortalized with large T antigen, and that an alpha3beta1-dependent pathway is required for sustained production of MMP-9 in the absence of other pathways.

[Effects of soil moisture and shading levels on photosynthetic characteristics of cotton leaves]

The effects of different soil moistures and shading levels on stomatal conductance(Gs), net photosynthetic rates(Pn), transpiration and leaf water potential(LWP) of cotton (variety Zhongmian No. 23) grown in pots from the seedling to flower bud stages in summer noon were evaluated. We designed three shading levels: no-shading(CK), 75% shading (DN), 40% shading(SN); and three soil moistures; 85%-100% (high water, HW), 65%-85% (medium water, MW) and 45%-65% (low water, LW) of field water-bolding capacity. The Gs of DN and SN increased by 16.69% and 28.01% compared with CK at HW, respectively, while the Pn of DN and SN declined by 45.74% and 20.54%, respectively. The Gs of DN and SN enhanced by 28.86% and 23.28% compareds with CK at MW, respectively, while the Pn of DN and SN decreased by 31.97% and 1.64%, respectively. The Gs of CK, DN and Sn did not exhibit significant differences at LW, while Pn of DN and SN reduced by 46.22% and 13.45%, respectively. Significant difference in Gs did not exist between DN and SN at the same soil moisture, but there was significant difference in Pa between them (except at LW). It was suggested that Gs declined with the increasing of leaf-to-air vapor pressure difference (VPD) and showed weak correlation with Pn by regression. The combined effects of soil moistures and shading levels on LWP and transpiration rate were not significant. There was no significant difference in LWP and transpiration rate among three shading treatments. Contrasted to treatment CK, intercellular CO2 concentration (Ci) in DN and SN at HW, MW and LW increased significantly, except no apparent change of Ci in SN at MW.

[Simultaneous pallidotomy and thalamotomy for Parkinson's disease with intractable tremor]

OBJECTIVE

To evaluate the clinical necessity, outcomes, safety, and indications of contemporary combined pallidotomy and thalamotomy for Parkinson's disease (PD) with intractable tremor.

METHODS

The UPDRS data from 20 patients who received simultaneous pallidotomy and thalamotomy were analyzed retrospectively. During the same period, 326 patients were subjected to unilateral pallidotomy. Improvement and complications between the two groups were compared.

RESULTS

Contemporary pallidotomy and thalamotomy effectively improved parkinsonian symptoms as did pallidotomy alone. This procedure completely abolished intractable tremor in all 20 patients. No permanent complications occurred.

CONCLUSIONS

Contemporary combination of pallidotomy and thalamotomy is effective and safe in treating regular parkinsonian symptoms and intractable tremor.

[Fibronectin in adhesion, spreading and proliferation of mandibular condylar cartilage cells on cytodex-3 microcarrier]

OBJECTIVE

The purpose of this study was to investigate the effects of exogenous fibronectin on the attachment and growth of mandibular condylar cartilage (MCC) cells on DEAE-dextran micro-carrier.

METHODS

MCC cells were harvested from newborn New Zealand white rabbits by sequential digestion with trypsin and collagenase. They were grown on the 20 mg/L fibronectin-coated and uncoated cytodex-3 micro-carrier. Samples were collected after 1, 3, 5, 7, 9, 11 days. The kinetics of adhesion and growth were observed with phase contrast microscope and environmental scanning electronic microscope (ESEM) and quantified by 0.1% crystal violet nuclear extrusion method.

RESULTS

MCC cells could rapidly attach and spread onto the fibronectin-coated cytodex-3, and nearly 60 percent cells attached to the micro-carrier within 2 hours. Spreading cells were flat and lowly refractile observed under phase contrast microscope. While the attachment and spreading of the cells in the untreated group were slow, and only 36 percent cells attached to the uncoated micro-carrier. However, most cells attached to the micro-carrier in both groups after 24 hours. The MCC cells attaching to FN-coated cytodex-3 observed under ESEM were flatter and adhered tightly with more processes (pseudopodia) stretching out from cytoplasm. In contrast, cells on untreated cytodex-3 remained regularly round even 24 hours after being plated. Meanwhile, there was an accelerated growth rate of the MCC cells on the fibronectin treated cytodex-3. The cell density in the FN treated group was higher than that of the untreated group at the end of the culture.

CONCLUSION

Fibronectin, one major glycoprotein of extracellular matrix, plays an important role in cell attachment and spreading. The better understanding of the extracellular matrix will be helpful in selecting the optimal substrate for cell growth in vitro.

[Soil nitrogen and organic matter losses under water erosion]

The results of artificial water-scoured experiment show that with the increase of water-scoured intensity, the losses of nitrate and ammonium in runoff, and those of organic matter and total N in sediment increased greatly, while the enrichment ratios of organic matter and total N in sediment reduced correspondingly. When the soils in gully-hilly loess region were fertilized with same amount of NH4NO3, the ammonium and nitrate loss in runoff was respectively 0.9-3.5% and 8.2-19.7% of the application amount. Nitrate mainly lossed in runoff, not in sediment. The correlation coefficient of soil erosion module, organic matter and total N loss with > 20 microns soil aggregates was -0.8935, -0.7928 and -0.8151, respectively. The content of > 20 microns soil aggregates could be used as an index to differentiate the soil organic matter and total N loss.

Bilateral pallidotomy for treatment of idiopathic Parkinson's disease

OBJECTIVE

To clarify the benefits and risks of patients undergoing bilateral posteroventral pallidotomy (BPVP) for patients with idiopathic Parkinson's disease (PD) and the differences between contemporaneous BPVP (CBPVP) and staged BPVP (SBPVP).

METHODS

Twenty patients underwent microelectrode-guided CBPVP and 26 SBPVP for bilateral PD symptoms. The data were retrospectively reviewed. Unified Parkinson's Disease Rating Scale (UPDRS) was used to evaluate the effects of these operations.

RESULTS

BPVP, either CBPVP or SBPVP, significantly improved patients' bilateral PD symptoms (P < 0.001). The improvement was consistently higher in "off" state than in "on" state. No statistical difference was observed in the improvement percentages of CBPVP, SBPVP1 and SBPVP2. CBPVP contributed greatly to L-dopa induced side effects (part IV). BPVP, SBPVP1, and SBPVP2 significantly improved cardinal parkinsonian signs but no difference was found among them. One patient after CBPVP developed hypophonia and swallowing problem, while 2 patients after SBPVP sustained hypophonia. These conditions were improved 3 months later.

CONCLUSIONS

BPVP may significantly improve bilateral signs of PD. It is safer than bilateral thalamotomy. CBPVP is applicable to some patients. BPVP may not cause mental impairment but shows a higher incidence rate of hypophonia. The practice of BPVP requires a refined surgical technique and a better understanding of pathophysiology of the basal ganglia.

[A clinical analysis of L-dopa induced dyskinesia treated by posteroventral pallidotomy for Parkinson's disease]

OBJECTIVE

To evaluate the outcome of microelectrode-guided posteroventral pallidotomy (PVP) for L-dopa induced dyskinesia in patients with Parkinson's disease.

METHODS

Thirty-six patients with dyskinesia were evaluated with unified Parkinson's disease rating scale (UPDRS) before and after operation. Duration and disability of dyskinesia were analyzed respectively.

RESULTS

The total surgical improvement for dyskinesia was 76.2%. Duration improvement was 88.8% and disability 79.7%. Significant change (P < 0.05) happened postoperatively. Seventeen patients were followed up for 3 months. The result showed a stable improvement for dyskinesia.

CONCLUSIONS

L-dopa induced dyskinesia may disappear or be improved after PVP. Surgical treatment promises a maximum L-dopa therapy without any severe pharmaceutical complications. Synergic treatment of drug and surgery are a new strategy for Parkinson's disease.

Enhancement of GABA-activated current by muscarine in rat dorsal root ganglion neurons

The modulation of GABA-gated ion channel responses to GABA, pentobarbital and diazepam by muscarine was studied in freshly isolated rat dorsal root ganglion neurons using a whole-cell patch-clamp technique. Muscarine enhanced current activated by 5 microM GABA dose-dependently with an EC50 of 40 +/- 2 microM. This potentiation was not blocked by pirenzepine, gallamine and atropine, the specific and non-specific muscarinic receptor antagonists. Muscarine shifted the GABA dose-response curve to the left, with the GABA EC50 decreased from 45 +/- 2 to 13 +/- 2 microM. The maximal response to GABA was suppressed to 89.3 +/- 4.6% as compared with the control (100%) by 80 microM muscarine. Muscarine potentiated GABA (1-100 microM)-activated current in a voltage-independent manner. Muscarine shifted the dose-response curve for pentobarbital enhancement of GABA-activated current to the left, and the enhancement of GABA-activated current by muscarine was additive to that of pentobarbital over all pentobarbital concentrations. Muscarine shifted the dose-response curve for diazepam (1-100 nM) enhancement of GABA-activated current to the left. However, muscarine attenuated the facilitatory effect of saturating concentrations of diazepam (> 100 nM). The potentiating effect of muscarine was blocked by 1 nM ethyl-beta-carboline-3-carboxylate, the inverse agonist of benzodiazepine receptors. These results suggest that GABA-gated ion channel responses to GABA and pentobarbital were potentiated by muscarine and the binding site(s) for muscarine might be related to those for diazepam.