Biomedical subjects

Hui Liu

Publications and source records attributed to Hui Liu.

At least 163 records · Page 9Linked to original sources

PubMed2004

Gene therapy of rat malignant gliomas using neural stem cells expressing IL-12.

Primary malignant brain tumors have a poor prognosis. This report investigates the potential for gene therapy of experimental brain tumors using neural stem cells (NSCs) expressing IL-12. In this study NSCs were isolated from the hippocampi of 3-5-month human embryos and used for lipofectamine mediated transfer of the IL-12 gene. Positive clones of anti-G418 were obtained and were proliferated in culture and expression of IL-12 was demonstrated by RT-PCR. For the in vivo studies three groups of rats were used and stereotactic injections were made into the striatum. In the first group C6 tumor cells were injected, in the second C6 cells and hNSCs. IL-12, and in the third C6 cells on Day 0 followed by hNSCs.IL-12 on day 5. The growth of the resulting tumors was monitored by magnetic resonance imaging (MRI) and after sacrifice by immunohistochemistry. Rats injected with C6 cells and hNSCs.IL-12 had a significantly prolonged survival. Injections of hNSCs.IL-12 were also made into established gliomas. The survival time was also significantly prolonged compared to controls. MR imaging demonstrated that there was initial growth of tumor followed by shrinkage and then disappearance. After sacrifice, tumor areas were studied by histochemistry. NSCs were often seen intermingled with tumor cells, particularly when they had been injected into established tumors; they were also present at the boundaries of the tumor mass. The immunohistochemical analysis showed that these infiltrates were mostly constituted by CD4(+) and CD8(+) T-lymphocytes, the CD8(+) being more numerous than the CD4(+). These findings indicated that NSCs engineered to release IL-12 could have a strong antitumor effect. Neural stem/precursor cells could be useful vectors in genetic approaches to brain tumors.

Animals↗

PubMed2004

Recombinant scFv antibodies against E protein and N protein of severe acute respiratory syndrome virus.

Three single chain antibodies (scFv) against the proteins of severe acute respiratory syndrome coronavirus (SARS-CoV) were isolated by phage display from an scFv antibody library. Bio-panning was carried out against immobilized purified envelope (E) and nucleocapsid (N) proteins of SARS-CoV. Their binding activity and specificity to E or N protein of SARS-CoV were characterized by phage-ELISA. Two of them, B10 and C20, could recognize non-overlapping epitopes of the E protein according to the two-site binding test result. Clone A17 could recognize N protein. The sequence of the epitope or overlapping epitope of scFv antibody A17 was PTDSTDNNQNGGRNGARPKQRRPQ. The affinity (equilibrium dissociation constant, K(d)) of SARS-CoV E protein was 5.7 x 10(-8) M for B10 and 8.9 x 10(-8) M for C20. The affinity of A17 for N protein was 2.1 x 10(-6) M. All three scFv antibodies were purified with affinity chromatography and determined by Western blot.

Amino Acid Sequence↗

PubMed2004

Accommodating ethnic diversity: a study of California hospice programs.

BACKGROUND: Studies have confirmed ethnic disparities in the use of hospice services and identified barriers that minorities face in accessing care. OBJECTIVES: We sought to determine whether hospices provide services that might affect minority participation. RESEARCH DESIGN: We surveyed California hospices to determine whether programs use diverse health care providers and volunteers, offer translation, diverse spiritual care, or outreach materials and whether they plan to expand such services. Linking the data to the California Office of Statewide Health Planning and Development annual home care and hospice survey and 2000 US Census, we used multivariate linear regression to evaluate the relationship of program characteristics (profit status, size, chain/freestanding status, urban/rural location, and proportion of nonwhite residents) to services that might affect minority participation. SUBJECTS: One hundred of 149 programs that we surveyed responded. RESULTS: Many programs offer translation (81%), diverse providers (63%) and volunteers (64%), and culturally diverse spiritual services (52%). Few (21%) were conducting outreach, but 23/25 programs expanding services reported plans to improve outreach. In multivariate models adjusted for program size, chain status, profit status, urban/rural location, proportion of nonwhite residents, we found that larger hospices and those in ethnically diverse zip codes were more likely to offer such services. Larger hospices are more likely to report expanding such services. CONCLUSIONS: Many hospices are making efforts to accommodate ethnically diverse patients, but a substantial number are not. Culturally appropriate care and outreach should be addressed in efforts to improve the acceptability and experience of hospice care among minorities.

California↗

PubMed2004

Hospice admission practices: where does hospice fit in the continuum of care?

OBJECTIVES: To evaluate selected hospice admission practices that could represent barriers to hospice use and the association between these admission practices and organizational characteristics. DESIGN: From December 1999 to March 2000, hospices were surveyed about selected admission practices, and their responses were linked to the 1999 California Office of Statewide Health Planning and Development's Home and Hospice Care Survey that describes organizational characteristics of California hospices. SETTING: California statewide. PARTICIPANTS: One hundred of 149 (67%) operational licensed hospices. MEASUREMENTS: Whether hospices admit patients who lack a caregiver; would not forgo hospital admissions; or are receiving total parenteral nutrition (TPN), tube feedings, radiotherapy, chemotherapy, or transfusions. RESULTS: Sixty-three percent of hospices restricted admission on at least one criterion. A significant minority of hospices would not admit patients lacking a caregiver (26%). Patients unwilling to forgo hospitalization could not be admitted to 29% of hospices. Receipt of complex medical care, including TPN (38%), tube feedings (3%), transfusions (25%), radiotherapy (36%), and chemotherapy (48%), precluded admission. Larger program size was significantly associated with a lower likelihood of all admission practices except restricting the admission of patients receiving TPN or tube feedings. Hospice programs that were part of a hospice chain were less likely to restrict the admission of patients using TPN, radiotherapy, or chemotherapy than were freestanding programs. CONCLUSION: Patients who are receiving complex palliative treatments could face barriers to hospice enrollment. Policy makers should consider the clinical capacity of hospice providers in efforts to improve access to palliative care and more closely incorporate palliation with other healthcare services.

Caregivers↗

PubMed2004

Simulation of the interaction between ScyTx and small conductance calcium-activated potassium channel by docking and MM-PBSA.

Computational methods are employed to simulate interaction of scorpion toxin ScyTx in complex with the small conductance calcium-activated potassium channel rsk2. All of available 25 structures of ScyTx in the Protein Data Bank determined by NMR were considered for improving performance of rigid protein docking of ZDOCK. Four main binding modes were found among a large number of predicted complexes by using clustering analysis, screening with expert knowledge, energy minimization, and molecular dynamics simulations. The quality and validity of the resulting complexes were further evaluated by molecular dynamics simulations with the generalized Born solvation model and by calculation of relative binding free energies with the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) in the AMBER 7 suit of programs. The complex formed by the 22nd structure of the ScyTx and rsk2 channel was identified as the most favorable complex by using a combination of computational methods, which contain further introduction of flexibility without restraining residue side chain. From the resulted spatial structure of the ScyTx and rsk2 channel, ScyTx associates the mouth of the rsk2 channel with alpha-helix rather than beta-sheet. Structural analysis first revealed that Arg(13) played a novel and vital role of blocking the pore of the rsk2 channel, whose role is remarkably different from that of highly homologous scorpion toxin P05. Between the interfaces in the ScyTx-rsk2 complex, strong electrostatic interaction and hydrogen bonds exist between Arg(13) of ScyTx and Gly-Tyr-Gly-Asp sequential residues located in the four symmetrical chains of the pore region. Simultaneously, five hydrogen bonds between Arg(6) of ScyTx and Asp(341)(C), Val(366)(C), and Pro(367)(C), and electrostatic interaction between Arg(6) of ScyTx and Asp(364)(B) and Asp(341)(C) are also found by structural analysis. In addition, His(31) located at the C-terminal of ScyTx is surrounded by Val(342)(A), Asp(364)(A), Met(365)(A), Pro(367)(B), and Asn(366)(B) within a contact distance of 4.0 A. These simulation results are in good agreement with experimental data and can effectively explain the binding phenomena between ScyTx and the potassium channel at the level of molecular spatial structure. The consistency between results of molecular modeling and experimental data strongly suggests that our spatial structure model of the ScyTx-rsk2 complex is reasonable. Therefore, molecular docking combined with molecular dynamics simulations followed by molecular mechanics Poisson-Boltzmann surface area analysis is an attractive approach for modeling scorpion toxin-potassium channel complexes a priori for further biological studies.

Animals↗

PubMed2004

A novel method to assay proteins in blood plasma after intravenous injection of plasmid DNA.

Gene therapy is expected to lead to new and useful methods to treat diseases. The development of assays to quantitate gene-therapy-derived proteins circulating in blood will be essential to investigate the effects and side effects of the introduced proteins. The purpose of this study is to evaluate whether a protein circulating at trace concentrations in blood can be measured by tagging a peptide corresponding to glucagon residues 19-29 onto its C-terminal end. We constructed plasmids encoding chimeric proteins and transferred them into rats by hydrodynamics-based delivery. When plasmids encoding human IL8-glucagon 19-29 chimeric protein were injected into rats to evaluate the accuracy of this method, there was a high correlation between chimeric proteins measured by an enzyme-linked immunosorbent assay for human IL8 and one by a radioimmunoassay for glucagon. Furthermore, when plasmids coding rat IFN gamma receptor IgG-Fc glucagon 19-29 chimeric protein were injected to evaluate the time course of chimeric proteins in blood plasma, we could calculate the concentrations in blood from 10 microl plasma samples using glucagon 19-29 tag as follows: 2815+/-2318 ng/ml after 4 hours (mean+/-s.D.), 6061+/-2789 ng/ml after 8 hours, 5752+/-2270 ng/ml after 12 hours, 2870+/-1062 ng/ml after one day, 1440+/-334 ng/ml after three days, 1120+/-433 ng/ml after seven days, and 281+/-162 ng/ml after 16 days. Blood sugar levels which might have been increased by glucagon did not increase even at peak chime- ric protein concentrations. These results demonstrate a useful and convenient method to assay gene therapy products circulating in blood using a glucagon 19-29 tagging vector.

Animals↗

PubMed2004

Topical delivery of different acyclovir palmitate liposome formulations through rat skin in vitro.

The objective of this investigation was to examine the permeation of acyclovir palmitate from various liposome formulations through hairless rat skin in vitro. The penetrated amount, permeability and intradermal retention of ACV-C16 were compared among various lipid compositions and different vesicle charges. We found that all of the liposome formulations resulted in higher flux and permeability of ACV-C16 than a common ointment form. The 'skin lipid' liposome provided the most effective transdermal delivery of incorporated ACV-C16. Presence or absence of cholesterol in the lipid bilayers did not reveal any difference in transdermal delivery of the associated ACV-C16. Intradermal retention of ACV-C16 from positive liposomes was significantly higher than that from other formulations. These findings suggested that liposomes itself might not penetrate through the skin, but enhance the transfer of incorporated ACV-C16. Liposomal lipid composition was the most important factor affecting the efficiency of transdermal delivery of incorporated drugs, but was not correlated with its phase transition temperature.

Acyclovir↗

PubMed2004

[Effects of protease inhibitors on intestinal absorption of insulin].

AIM: To study the effects of protease inhibitors on the large and small intestinal absorption of insulin in rats and to explore the mechanism of various protease inhibitors in different intestinal regions. METHODS: The intestinal absorption of insulin was evaluated by its hypoglycemic effect and serum insulin level using an in situ loop method with the washing treatment. RESULTS: Administration of insulin alone did not decrease the glucose level at either intestinal region with or without the washing treatment. With the unwashing treatment, there were no hypoglycemic effects in small intestinal loop when coadministration of insulin with protease inhibitors. With the washing treatment, the biological effects of insulin were amplified a little in small intestinal loop; obvious hypoglycemic effects were found in large intestinal loop with or without the washing treatment. The effectiveness of protease inhibitors was susceptible to their categories, concentrations and activities of proteolytic enzymes in different regions. The efficacy order of various protease inhibitors for enhancing hypoglycemic response of insulin was: leupeptin > sodium glycocholate > bacitracin > bestatin > cystatin; the percutaneous enhancement effects were observed in the presence of either sodium glycocholate or bacitracin. CONCLUSION: Coadministration of protease inhibitors could increase the insulin efficacy more effectively in the large intestine than in the small intestine.

Animals↗

PubMed2004

Cloning and functional analysis of the promoter of ZNF268 gene.

The human ZNF268 gene is a novel C2H2 zinc finger gene restrictively expressed in the liver of human embryo. As an initial study on the regulation of its expression, 2.5 kb fragment of the ZNF268 5'-flanking region was cloned from human genome by PCR. This fragment was inserted into pEGFP1 vector and then the recombinant plasmid was transfected into several cell lines by liposomal transfection method. EGFP expression was observed in four cell lines under confocal laser scanning microscope. A series of 5'-deletion fragments from -2456(-)+77 bp to -20(-)+77 bp were inserted into pCAT-Basic vector to construct recombinant reporter plasmids, which were then transfected into Hela cells for deletion analysis. Results of deletion analysis revealed that an important region for transcriptional activity lies between -156 and -20 bp.

Cloning, Molecular↗

PubMed2004

Effects of raloxifene hydrochloride on bone mineral density, bone metabolism and serum lipids in Chinese postmenopausal women with osteoporosis: a multi-center, randomized, placebo-controlled clinical trial.

BACKGROUND: Raloxifene has been approved for prevention and treatment of postmenopausal osteoporosis in Caucasian women. It also has some positive effects on serum lipids in Caucasians. The objective of this study was to determine the effect of raloxifene hydrochloride on lumbar spine and total hip bone mineral density (BMD), bone metabolism, and serum lipids in Chinese postmenopausal women with osteoporosis. METHODS: This was a multi-center, randomized, double-blind, placebo-controlled clinical trial in which 204 postmenopausal Chinese women with osteoporosis were assigned to receive raloxifene (60 mg) or placebo treatment daily for 12 months. BMD, serum bone metabolism markers, and serum lipids were measured before and after drug administration. BMD was measured by Dual-Energy X-Ray Absorptiometry (DEXA) and bone metabolism markers were analyzed by one-step enzyme-linked immunosorbent assay. Serum lipids were measured by enzymatic analysis. RESULTS: At the end of the 12-month study, lumbar spine BMD increased in both groups with a mean increase of (3.3 +/- 4.8)% in the raloxifene group and (1.0 +/- 4.9)% in the placebo group (P < 0.001). There was a mean increase in total hip BMD of (1.4 +/- 4.8)% in the raloxifene group and a mean decrease of (0.9 +/- 5.0)% in the placebo group (P < 0.001). No subject in the raloxifene group had a new vertebral fracture and 5 placebo subjects had new fractures (P > 0.05). In the raloxifene group, the median decreases in the biochemical markers of bone metabolism serum osteocalcin and C-telopeptide were 41.7% and 61.5%, respectively. These changes were statistically significant compared with those in the placebo group (10.6% and 35.6%, P < 0.001, respectively). Both total cholesterol and low-density lipoprotein cholesterol decreased significantly in the raloxifene group compared with those in the placebo group (P < 0.001, respectively) and there was no significant effect of raloxifene on high-density lipoprotein cholesterol and triglycerides compared with placebo. CONCLUSIONS: Raloxifene 60 mg/d for 12 months significantly increases lumbar spine and total hip BMD, significantly decreases bone turnover, and has favourable effects on serum lipids in Chinese postmenopausal women with osteoporosis.

Aged↗

PubMed2004

[Effects of hydrocortisone sodium succinate on sodium current in human and guinea pig cardiac myocytes].

AIM: To study the effects of hydrocortisone sodium succinate on sodium current in human atrial myocytes and in guinea pig ventricular myocytes. METHODS: Single cardiac myocytes were isolated by enzyme. The effects of hydrocortisone sodium succinate on sodium current (INa) were assessed by applying whole-cell patch clamp techniques. RESULTS: Hydrocortisone sodium succinate (1, 3, 10 micromol x L(-1)) was shown to inhibit INa of both human atrial myocytes and guinea pig ventricular myocytes in concentration dependent manner and the IC50 were 6.97 and 8.74 micromol x L(-1), respectively. The inhibition effects acted quickly (1-3 min) and the maximal activating voltage of INa was not changed in both human and guinea pig cardiac myocytes. CONCLUSION: Hydrocortisone sodium succinate can exhibit inhibitory effects on INa in both human and guinea pig cardiac myocytes, and its inhibitory effects act rapidly, which are not consistent with genomic effects, so there may be nongenomic effects.

Adolescent↗

PubMed2004

[Effects of copper (Cu2+) and Cu-EDTA complex on the induction of HSP70 in the fish brain].

The effects of copper (Cu2+) and Cu-EDTA complex on the induction of HSP70 in the fish brain were studied. After the fish (Carassius auratus) were exposed to the experimental concentrations for forty days, the SDS-PAGE and Western Blotting techniques were used to detect the expression level of HSP70 in the fish brain. The results showed that Cu2+ and Cu-EDTA complex can induce the expression of HSP70 significantly. Comparing with the test groups exposed to Cu2+, the Cu-EDTA complex had changed the bioavailability and decreased the toxicity of the heavy metal. It was found that the fish exposed to the concentration of Cu2+ which below the national fishery water quality standard of 0.01 mg/L , also had a significant increase in the expression level of HSP70. Therefore, HSP70 as an environmental biomarker can be a more sensitive and rapid indicator than conventional end points in the aquatic ecosystem.

Animals↗

PubMed2004

[Aspirin inhibits proliferation and expression of p44/42 MAPK phosphorylation in vascular endothelial cells].

OBJECTIVE: To observe the effects of aspirin on vascular endothelial cell proliferation in vitro and on the activity of p44/p42 mitogen-activated protein kinase (MAPK) phosphorylation. METHODS: ECV 304 cells cultured in vitro were treated with aspirin (1, 2, 5, and 10 mmol/L, respectively) and observed for their proliferation in comparison with the control group. The ratio of cell proliferation was determined by non-radioactive MTS/PES assay. The expression of phosphorylated p44/42 MAPK protein was evaluated by the immunoblotting technique using anti-p44/42 phospho-MAPK antibody. RESULTS: The proliferation rate of the endothelial cell was 1.533+/-0.286 in the control group, and 0.459+/-0.107, 0.708+/-0.125, 0.953+/-0.149 and 1.253+/-0.225 in aspirin-treated groups corresponding to aspirin concentrations of 10, 5, 2 and 1 mmol/L, respectively. It was shown that aspirin significantly inhibited the vascular endothelial cell proliferation at the concentration above 1 mmol/L (P<0.05), in a dose-dependent manner as compared with the control group (P<0.05). The expression of phosphorylated p44/42 MAPK protein was significantly inhibited by aspirin. CONCLUSIONS: Aspirin decreases vascular endothelial cell proliferation, and arrest of endothelial cell proliferation may be an important mechanism by which aspirin produces protective effect against acute coronary disease.

Aspirin↗

PubMed2004

[High mobility group box-1 protein activates Janus kinase-signal transducer and activator of transcription pathway in rat peritoneal macrophages].

OBJECTIVE: To investigate the potential signal transduction mechanism in high mobility group box-1 protein (HMGB1)-induced inflammatory response in rat peritoneal macrophages. METHODS: Peritoneal macrophages obtained from male Wistar rats were incubated for 3 days before they were stimulated by HMGB1 (10 microg/ml). At various time points after HMGB1 stimulation, macrophages were denatured directly in cell culture flasks to detect activation of Janus kinase-2 (JAK2), signal transducer and activator of transcription-1 (STAT1) and STAT3 by immunoprecipitation, Western blotting and electrophoretic mobility shift assay, respectively. RESULTS: HMGB1 stimulation could activate STAT1 and STAT3 in peritoneal macrophages in 2 hours, among them the activation of STAT3 appeared to be the quickest, peaking as early as 10 minutes after stimulation. But no marked change in JAK2 activity was observed within 2 hours following HMGB1 stimulation. CONCLUSION: These data suggest that Janus kinase-signal transducer and activator of transcription pathway might be involved in regulation of HMGB1-induced inflammatory response in peritoneal macrophages.

Animals↗

PubMed2004

[Construction of recombinant vector expressing ALAS2 gene in X-linked sideroblastic anemia].

X-linked sideroblastic anemia (XLSA) is caused by mutations of erythroid-specific 5-aminolevulinate synthetase (ALAS2) gene. In this study a eukaryotic expression vector of ALAS2 was constructed and transfected into eukaryotic cells to observe the expression of ALAS2 gene. The full length cDNA of ALAS2 gene was inserted into plasmid pDs-red2-N1, named pDs-red2-N1/ALAS2. Then, the vector was transfected into K562 cells via electroporation. At 48 hours after transfection, total RNA from K562 cells was extracted, expressions of ALAS2 gene and protein with red fluorescence in the K562 cells were detected by RT-PCR and flow cytometry, respectively. The vector was also transfected into COS 7 cells via liposome. Both mRNA and protein expression in COS7 cells were detected by RT-PCR and fluorescence microscopy. The result showed that after the pDs-red2-N1/ALAS2 eukaryotic expression vector was digested by KpnI and BamHI, two fragments of 4 700 bp and 1 764 bp were displayed by electrophoresis on agarose gel. Sequence method confirmed that the sequence was correct. RT-PCR amplified the total RNA extracted from the transfected K562 and COS7 cells, and could find mRNA of ALAS2 gene that can't be found in K562 and COS7 cells usually. The expressions of both fluorescein and ALAS2 were significantly increased. The percentage of positive cells reached about 19.2% and 10.7%, respectively. ALAS2 expression lasted for 10 days in COS7 cells and the peak was at the third day. It is concluded that the eukaryotic expression vector of ALAS2 gene is successfully constructed; K562 and COS7 cells transfected with the vector via electroporation and liposome can express ALAS2 protein. So, the vector has the potential in gene replacement and can be used for patients with XLSA in future.

5-Aminolevulinate Synthetase↗

PubMed2004

[Relationship between the reduction of FHIT expression and the development of cervical carcinoma].

OBJECTIVE: To explore the relationship between reduction of FHIT expression of fragile histidine triad (FHIT) and the development of cervical carcinoma. METHODS: Expression of the FHIT product was detected by immunohistochemistry in 22 normal cervices and 35 cervical intra-epithelial neoplasias (CINs) as well as 60 primary invasive cervical carcinomas. RESULTS: The rates for loss or reduction of expression of FHIT protein in the squamous epithelium of normal cervices, CIN I-II, CIN III and noninvasive carcinoma and invasive cervical carcinoma were 0% (0/22), 20% (4/20), 53.3% (8/15), 81.7% (49/60) respectively (P<0.05). Among the well differentiated, intermediately differentiated and poorly differentiated invasive cervical carcinoma, the rates for loss or reduction of expression of FHIT protein were 60.0% (6/10), 70.0% (14/20), and 96.7% (29/30) respectively (P<0.05). The rate of the impaired FHIT protein expression in the invasive cervical carcinoma with lymph node metastasis (90.9%) was higher than that without lymph node metastasis (79.6%). CONCLUSION: The impaired FHIT protein expression might be a useful indicator in identifying the possibility of the progression of advanced CINs into invasive cervical carcinoma. FHIT protein expression might indicate the clinical characteristic of cervical carcinoma cells and the prognosis of cervical carcinoma.

Acid Anhydride Hydrolases↗

PubMed2004

[Study on DNA damage and expression of RAS gene in L-02 cells exposed to chlorinated drinking water extracts].

OBJECTIVE: To study the DNA damage and expression of RAS gene in human fetal hepatocytes (L-02) induced by chlorinated drinking water extracts, and to explore the possible molecular mechanism of its genotoxicity . METHODS: L-02 cells were exposed to chlorinated drinking water extracts at the concentration of 0.167, 1.67, 16.7 and 167 ml/ml culture medium. Single cell gel electrophoresis (SCGE) and in situ hybridization (ISH) assay were used to detect DNA damage and the expression of RAS gene in L-02 cells. DMSO (10 ml/L) and B(a)P (200 micromol/L) were used as solvent control and positive control respectively. RESULTS: Chlorinated drinking water extracts led to a significant increase of DNA migration in the L-02 cells at the concentrations of 16.7 and 167 ml/ml culture medium in comparison with solvent control. Significantly higher expressions of RAS gene was found in the L-02 cells exposed to all concentrations of chlorinated drinking water extracts than in that of solvent control group. There was a significant correlation (r = 0.99) between RAS gene expression and DNA migration when the concentration of chlorinated drinking water extracts was between 0.167 and 16.7 ml/ml. CONCLUSION: Chlorinated drinking water extracts could induce obvious DNA damage and RAS gene expression in L-02 cells, and RAS gene expression might be affected by DNA damage.

Cell Line↗

PubMed2004

[Effects of capsaicin on IA and IK in cultured trigeminal ganglion neurons of rat].

AIM: To investigate the effect of capsaicin on IA and IK in cultured rat trigeminal ganglion (TG) neurons. METHODS: Whole-cell patch clamp technique was used to record the IA and IK before and after capsaicin perfusion at different concentrations. RESULTS: In capsaicin-sensitive (CS) neurons, capsaicin was shown to selectively inhibit IA in dose-dependent manner, the IC50 was 0.99 micromol x L(-1). Yet capsaicin showed no inhibitory effect on IK, capsaicin (10 micromol x L(-1)) only slightly inhibited IK by 13.2%. In capsaicin-insensitive (CIS) neurons, capsaicin (1 micromol x L(-1)) showed no significant inhibitory effect on IA and IK, capsaicin (10 micromol x L(-1)) only slightly inhibited IA and IK by 16.8% and 15.3%, respectively. Neither 1 micromol x L(-1) nor 10 micromol x L(-1) capsaicin showed effect on the G-V curve of IA and IK. CONCLUSION: Capsaicin was found to selectively inhibit the IA current in CS neurons, and this effect may contribute to hyperalgesia when capsaicin was first used.

Animals↗