Biomedical subjects

T L Lee

Publications and source records attributed to T L Lee.

At least 37 records · Page 2Linked to original sources

PubMed2001

Detection of microchimerism by PCR is a function of amplification strategy.

BACKGROUND: Suitable detection methods are needed to support larger studies of microchimerism and the allogeneic exposures that may be etiologically related to it. STUDY DESIGN AND METHODS: A twotier PCR strategy for microchimerism detection was developed on the basis of the observation that assay sensitivity for the detection of microchimerism depends on the specificity with which primer pairs recognize sequences unique to the minor population. First, specimens are tested to determine the host HLA class II genotype by using a locus-specific PCR strategy with low sensitivity for microchimerism. Then, a sequence-specific PCR analysis having high sensitivity for detection of microchimerism is applied to detect and quantitate the minor population. Locus-specific, group-specific, and sequence-specific amplification strategies for the detection of distinct minor WBC populations prepared ex vivo were compared. In addition, 39 clinical samples from patients with known transfusion-associated microchimerism and 20 umbilical cord blood (CB) specimens containing maternal WBCs were studied. RESULTS: Locus-specific amplification detected 17 (94%) of 18 cases in which microchimerism was present at 10 percent, but only 1 of 51 cases with microchimerism < or = 1 percent. Group-specific amplification detected all 63 cases with minor populations present at > or = 0.10 percent, but only 16 of 21 cases at the 0.01 percent level. Sequence-specific amplification detected 100 percent of cases down to the 0.01 percent level. When applied to clinical samples, locus-specific amplification reliably identified the major population but proved insensitive to low-level minor populations. CONCLUSIONS: For the detection of microchimerism, assay sensitivity is a function of amplification strategy. These results suggest a simple approach to population screening for microchimerism: the background population of WBCs is typed by a locus-specific method, while minor population(s) can then be sought by using one or several sequence-specific amplifications.

Alleles↗

PubMed2001

Adenomatous polyposis coli gene mutation and decreased wild-type p53 protein expression in oral submucous fibrosis: a preliminary investigation.

OBJECTIVE: The purpose of this study was to identify the adenomatous polyposis coli (APC) tumor suppressor gene mutation and level of wild-type p53 protein expression in patients with oral submucous fibrosis (OSF). STUDY DESIGN: Cells from OSF and control subjects were cultured in Dulbecco modified Eagle medium with 10% fetal bovine serum at 37 degrees C. Genomic DNA was extracted from cultured cells and used as a template for polymerase chain reaction amplification of the APC tumor suppressor gene. The presence of wild-type p53 protein in cell lysates of cultured cells was analyzed by Western blot. Data were analyzed by the sign test for nonparametric samples and by analysis of variance. RESULTS: The results showed that the APC gene of explant cultured cells from OSF patients (8/8) had a CGA-to-GGA transition mutation at codon 498 that resulted in an Arg-to-Gly missense mutation (P <.01). All (8/8) normal HGF cultures revealed expression of the wild-type APC protein. Cells cultured from 7 of 8 OSF patients were also found to have a single nucleotide deletion at nucleotide 1494 that resulted in creating a stop codon (TGA) at codon 504 (P <.01). This created a premature signal for the endpoint of translation and thus resulted in the generation of a truncated protein product that encodes a polypeptide of 503 amino acid residue. It was found that wild- type p53 protein in human gingival fibroblast cell cultures was significantly higher than in OSF cells (P <.01). CONCLUSION: Alterations of the APC and wild-type p53 tumor suppressor genes in OSF may imply a risk for progression to oral cancer.

Adenomatous Polyposis Coli↗

PubMed2001

Two novel quantitative trait loci on mouse chromosomes 6 and 4 independently and synergistically regulate plasma apoB levels.

An elevated plasma apolipoprotein B (apoB) level is a strong predictor of atherosclerosis and coronary heart disease. Epidemiologic and family linkage studies have suggested a genetic basis for the wide variations of plasma apoB levels in the general population. Using a human apoB transgenic (HuBTg) mouse model, we have previously shown that hepatic apoB-100 secretion is a major determinant of the high and low plasma human apoB levels in HuBTg mice of the C57BL/6 (B6) and 129/Sv (129) strains, respectively. In the present article, we present the identification of two novel quantitative trait loci (QTL) as major regulators of plasma human apoB levels in the F(2) and N(2) (backcrossed) offspring (n = 572) derived from crosses between the B6 and 129 mouse strains. These loci were designated ApoB regulator genes (Abrg), because the gene products are likely to be involved in the regulation of plasma apoB levels either directly or indirectly. The first locus, designated Abrg1, was mapped to chromosome 6 in 8-week-old male and female mice with a combined logarithm of odds ratio (LOD) score of 14 at the D6Mit55 marker ( approximately 45.9 cM). Abrg1 contributed approximately 35% of the genetic variance. The second locus, designated Abrg2, was mapped to chromosome 4 with an LOD score of 8.6 in 8-week-old male mice but an LOD score of only 2.0 in 8-week-old female mice at the D4Mit27 marker ( approximately 35 cM). Abrg2 contributed approximately 26% of the genetic variance. Epistasis between Abrg1 and Abrg2 was detected and accounted for approximately 12% of the genetic variance. The combination of these two QTL has major effects (>70%) on the regulation of plasma human apoB levels in the tested population. In summary, we have identified two novel loci that have a major role in the regulation of plasma apoB levels and are likely to regulate the secretory pathway of apoB. The human orthologs for the Abrg loci are strong candidates for human disorders characterized by altered plasma apoB levels, such as FCHL and familial hypobetalipoproteinemia.

Analysis of Variance↗

PubMed2000

One-codon alternative splicing of the CpG MTase Dnmt1 transcript in mouse somatic cells.

The genomic methylation patterns in the mammalian somatic cells are presumably maintained by a single enzyme, dnmt1. In mouse, this DNA (cytosine-5)-methyltransferase, or CpG MTase, is encoded by the Dnmt1 gene. We now present evidence that in different tissues and cell types, the primary transcript of mouse dnmt1 is alternatively spliced to generate two poly-(A) RNAs of approximately similar abundance. This alternative splicing most likely originates from the existence of two tandemly arranged acceptor sites separated by only 3 nt. The two Dnmt1 mRNAs thus encode two CpG MTases differing by two amino acids. We discuss the implications of the discovery of two dnmt1 isozymes, instead of one enzyme as previously thought, in the somatic cells of both mouse and human.

Alternative Splicing↗

PubMed2000

Incidence of and breed-related risk factors for gastric dilatation-volvulus in dogs.

OBJECTIVE: To compare incidence of and breed-related risk factors for gastric dilatation-volvulus (GDV) among 11 dog breeds (Akita, Bloodhound, Collie, Great Dane, Irish Setter, Irish Wolfhound, Newfoundland, Rottweiler, Saint Bernard, Standard Poodle, and Weimaraner). DESIGN: Prospective cohort study. ANIMALS: 1,914 dogs. PROCEDURE: Owners of dogs that did not have a history of GDV were recruited at dog shows, and the dog's length and height and depth and width of the thorax and abdomen were measured. Information concerning the dogs' medical history, genetic background, personality, and diet was obtained from owners, and owners were contacted by mail and telephone at approximately 1-year intervals to determine whether dogs had developed GDV or died. Incidence of GDV based on the number of dog-years at risk was calculated for each breed, and breed-related risk factors were identified. RESULTS AND CLINICAL RELEVANCE: Incidence of GDV for the 7 large (23 to 45 kg [50 to 99 lb]) and 4 giant (> 45 kg [> 99 lb]) breeds was 23 and 26 cases/1,000 dog-years at risk, respectively. Of the 105 dogs that developed GDV, 30 (28.6%) died. Incidence of GDV increased with increasing age. Cumulative incidence of GDV was 5.7% for all breeds. The only breed-specific characteristic significantly associated with a decreased incidence of GDV was an owner-perceived personality trait of happiness.

Age Factors↗

PubMed2000

Molecular cloning, characterization, and expression of a cDNA coding Copper/Zinc superoxide dismutase from black porgy.

A full-length complementary DNA (cDNA) clone encoding a putative copper/zinc superoxide dismutase (Cu/Zn-SOD) was amplified by a Polymerase Chain Reaction (PCR) based technique from cDNA synthesized from black porgy, Acanthopagrus schlegeli, mRNA. Nucleotide sequence analysis of this cDNA clone revealed that it comprised a complete open reading frame coding for 154 amino acid residues. The deduced amino acid sequence showed slightly higher identity (72.8-78.1%) with shark and swordfish Cu/Zn-SOD than with Cu/Zn-SOD from mammalian (68.1-70.7%) and plant (55.5-56.5%) sources. The residues required for coordinating copper and zinc are conserved as they are among all reported Cu/Zn-SOD sequences. The deduced amino acid sequence lacks mitochondria targeting sequence, which suggests that the black porgy cDNA clone encodes a cytosolic Cu/Zn-SOD. The coding region of Cu/Zn-SOD from black porgy was introduced into an expression vector, pET-20b(+), and transformed into Escherichia coli AD494(DE3)pLysS. A predominant achromatic zone was detected by activity staining of native PAGE. This indicates that the Cu/Zn-SOD cDNA clone can express active Cu/Zn-SOD enzyme in E. coli.

Amino Acid Sequence↗

PubMed2000

Interaction of Helicobacter pylori eradication and non-steroidal anti-inflammatory drugs on gastric epithelial apoptosis and proliferation: implications on ulcerogenesis.

BACKGROUND: Apoptosis is associated with loss of gastric mucosal integrity and may play an important role in ulcer development. AIM: To examine how Helicobacter pylori and NSAIDs interact to effect apoptosis and proliferation of the gastric mucosa. METHODS: Patients presenting with musculoskeletal pain requiring NSAID treatment and without previous exposure to NSAID or pre-existing ulcers were recruited. Patients were divided into three groups: (A) H. pylori-infected; (B) H. pylori-eradicated; and (C) non-infected patients. They were given naproxen for 8 weeks. Patients with non-ulcer dyspepsia and H. pylori infection who were given anti-Helicobacter therapy were recruited as controls (D). Endoscopy was performed at baseline and 8-weeks after receiving naproxen. Gastric antral biopsies were obtained to assess apoptosis by terminal uridine deoxynucleotidyl nick end-labelling (TUNEL) and proliferation by Ki67 immunostaining. RESULTS: A total of 55 patients were studied. H. pylori-positive patients had a higher apoptosis and proliferation index at baseline than non-infected patients (P < 0.0001), and eradication of H. pylori resulted in a significant reduction in these parameters. The NSAID induced apoptosis in non-infected subjects (P=0.03) whilst apoptosis was reduced in H. pylori-positive patients receiving NSAID (P=0.02). After 8 weeks of NSAID, post-treatment apoptosis was significantly higher in patients with persistent H. pylori infection than in non-infected patients (P=0.01). CONCLUSIONS: Eradication of H. pylori prior to NSAID therapy significantly reduces the level of apoptosis in the gastric mucosa, which may contribute to maintaining mucosa integrity and preventing ulcer development.

Adult↗

PubMed2000

An assessment of the effects on coagulation of midtrimester and final-trimester amniotic fluid on whole blood by Thrombelastograph analysis.

UNLABELLED: The Thrombelastograph((R)) test (TEG; Haemoscope Corporation, Skokie, IL) was used to assess the effects of midtrimester and final-trimester amniotic fluid (AF) on whole blood coagulation. Different volumes of midtrimester and final-trimester AF were added to whole blood from nonpregnant volunteers in a series of TEG tests. The addition of both midtrimester and final-trimester AF resulted in significant decreases in reaction time (P < 0.001) and time from reaction to a fixed level of clot firmness (P < 0.05) and significant increases in angle (P < 0.05) and coagulation index (P < 0.05) values. This reflects accelerated clot initiation and propagation. There was no significant change in the maximal amplitude or % lysis at 30 and 60 min with the addition of either midtrimester or final-trimester AF. There was no significant difference between the effects of midtrimester and final-trimester AF on whole blood TEG. TEG may be an additional useful tool in the treatment of coagulopathy in AF embolism. IMPLICATIONS: We used the Thrombelastograph((R)) test (Haemoscope Corporation, Skokie, IL) to assess the effects of midtrimester and final-trimester amniotic fluid (AF) on whole blood coagulation. Results demonstrate that AF accelerates clot initiation and propagation. The Thrombelastograph((R)) test may be useful in assessing coagulopathy in patients with AF embolism.

Adult↗

PubMed2000

Transcriptional repression by Drosophila methyl-CpG-binding proteins.

C methylation at genomic CpG dinucleotides has been implicated in the regulation of a number of genetic activities during vertebrate cell differentiation and embryo development. The methylated CpG could induce chromatin condensation through the recruitment of histone deacetylase (HDAC)-containing complexes by methyl-CpG-binding proteins. These proteins consist of the methylated-DNA binding domain (MBD). Unexpectedly, however, several studies have identified MBD-containing proteins encoded by genes of Drosophila melanogaster, an invertebrate species supposed to be void of detectable m(5)CpG. We now report the genomic structure of a Drosophila gene, dMBD2/3, that codes for two MBD-containing, alternatively spliced, and developmentally regulated isoforms of proteins, dMBD2/3 and dMBD2/3Delta. Interestingly, in vitro binding experiments showed that as was the case for vertebrate MBD proteins, dMBD2/3Delta could preferentially recognize m(5)CpG-containing DNA through its MBD. Furthermore, dMBD2/3Delta as well as one of its orthologs in mouse, MBD2b, could function in human cells as a transcriptional corepressor or repressor. The activities of HDACs appeared to be dispensable for transcriptional repression by dMBD2/3Delta. Finally, dMBD2/3Delta also could repress transcription effectively in transfected Drosophila cells. The surprisingly similar structures and characteristics of the MBD proteins as well as DNA cytosine (C-5) methyltransferase-related proteins in Drosophila and vertebrates suggest interesting scenarios for their roles in eukaryotic cellular functions.

Alternative Splicing↗

PubMed2000

Acupuncture and chronic pain management.

INTRODUCTION: Although acupuncture has been widely used to treat a variety of pain conditions, convincing scientific evidence for its efficacy is lacking. Earlier randomised controlled trials attempted to follow a double-blind, placebo-controlled model. This approach has encountered many problems such as the virtual impossibility of blinding the acupuncturist and the uncertainties inherent in choosing control acupuncture points. The objective of this review is to assess if acupuncture is an effective treatment for chronic pain. In addition, a number of key methodological issues that arise in the controlled evaluation of acupuncture will be discussed. METHODS: This review is based on the result of previous reviews, meta-analyses and consensus conference. The search was performed with MEDLINE (from 1966), EMBASE (from 1980) and Cochrane library (1999, volume 1). Only randomised trials of acupuncture (involved needling) for subjects with chronic pain published in English were included. RESULTS: Basic science research has demonstrated convincingly that at least in the context of acute pain, acupuncture's effects are related to the release of a variety of natural opioids. Acupuncture has been shown to be effective for postoperative dental pain. There are reasonable studies showing relief of pain with acupuncture on diverse pain conditions such as menstrual cramps, tennis elbow, low back pain and fibromyalgia. This suggests that acupuncture may have a more general effect on pain. However, there are also studies which provide equivocal results because of design, sample size and other factors. The issue is further complicated by inherent difficulties in the use of appropriate controls, such as placebo and sham acupuncture groups. CONCLUSION: As most of the studies were of poor methodological quality, there is a need for further high quality randomised controlled trials. Future studies should also have larger sample sizes, use a valid acupuncture treatment, and have both a short-term and long-term follow-up.

Acupuncture Therapy↗

PubMed2000

Use of sedation in dentistry.

Fear and avoidance of dental treatment are major deterrents to oral health. Sedation can be used to control both the patient's fear and anxiety so that proper dental care can be provided for these patients. The purpose of this article is to discuss the use of sedation in dentistry and to provide a recommendation on the requirements and medico-legal aspects of sedation for the practitioner interested in incorporating sedation into their practice.

Anesthesia, Dental↗

PubMed1999

Two major forms of DNA (cytosine-5) methyltransferase in human somatic tissues.

Thus far, only one major form of vertebrate DNA (cytosine-5) methyltransferase (CpG MTase, EC 2.1.1.37) has been identified, cloned, and extensively studied. This enzyme, dnmt1, has been hypothesized to be responsible for most of the maintenance as well as the de novo methylation activities occurring in the somatic cells of vertebrates. We now report the discovery of another abundant species of CpG MTase in various types of human cell lines and somatic tissues. Interestingly, the mRNA encoding this CpG MTase results from alternative splicing of the primary transcript from the Dnmt1 gene, which incorporates in-frame an additional 48 nt between exons 4 and 5. Furthermore, this 48-nt exon sequence is derived from the first, or the most upstream, copy of a set of seven different Alu repeats located in intron 4. The ratios of expression of this mRNA to the expression of the previously known, shorter Dnmt1 mRNA species, as estimated by semiquantitative reverse transcription-PCR analysis, range from two-thirds to three-sevenths. This alternative splicing scheme of the Dnmt1 transcript seems to be conserved in the higher primates. We suggest that the originally described and the recently discovered forms of CpG MTase be named dnmt1-a and dnmt1-b, respectively. The evolutionary and biological implications of this finding are discussed in relation to the cellular functions of the CpG residues and the CpG MTases.

Alternative Splicing↗

PubMed1999

Identification of human, rat and mouse nocistatin in brain and human nocistatin in brain and human cerebrospinal fluid.

Nocistatin was recently isolated from bovine brain and shown to block hyperalgesia and allodynia induced by nociceptin and prostaglandin (PG) E2. The counterparts of human, rat and mouse are deduced from their precursor prepronociceptin to be 30, 35, and 41 residue peptide respectively. To identify these mature forms of nocistatin, three peptides were synthesized and a detection program for nocistatin was developed, using high pressure liquid chromatography (HPLC) along with specific radioimmunoassay (RIA). Nocistatin extracted from human, rat and mouse brain were subjected to HPLC and nocistatin-like immunoreactivity (NST-IR) was determined. All three species showed two NST-IR peaks, one of which coincided with that of the corresponding putative nocistatin. The same NST-IR was also detected in human cerebrospinal fluid (CSF).

Amino Acid Sequence↗

PubMed1999

Influence of temperature, pH and naloxone on the antinociceptive activity of Channa striatus (haruan) extracts in mice.

We have previously shown that extracts from the snakehead fish, Channa striatus (haruan), have antinociceptive activity on their own, and enhance morphine antinociception. In furtherance of that study, we investigated the effects of temperature, pH and naloxone on the antinociceptive effects of haruan extracts in the mouse abdominal constriction test. The effects of temperature were only studied on mucus extracts since the fillet extract is prepared at high temperature under pressure. There was a general loss of inhibitory activity from 88.4% at 0 degrees C to 61.1% at 80-100 degrees C, though this was only significant at 80 degrees C. The effects of pH were studied on both extracts. Lowering the mucus extract pH to 6.0 (unadjusted pH 7.4) did not significantly affect its activity, while raising it to 8.0 attenuated its activity. Similarly, pH changes had no effect on the fillet extract except at pH 8.0 which produced apparently lower antinociception. Pretreatment with naloxone (4 mg/kg) had no significant effect on the inhibitory effects of either extract in the abdominal constriction test. These results suggest that the active ingredient(s) of these extracts is (are) relatively stable over a wide range of temperature and between pH 6.0 and 8.0. That would be consistent with the possibility of a glycoprotein, polypeptide or polysaccharide.

Analgesics↗

PubMed1999

Comparison of sevoflurane with propofol for laryngeal mask airway insertion in adults.

UNLABELLED: We performed a prospective, randomized, controlled trial to compare the quality and ease of laryngeal mask airway (LMA) insertion after either rapid inhaled sevoflurane or i.v. propofol induction of anesthesia. Seventy-six unpremedicated ASA physical status I or II patients were anesthetized with either a single vital capacity breath of sevoflurane 8% or i.v. propofol 3 mg/kg, which produced equally rapid loss of consciousness (40.5 +/- 13.9 vs 37.7 +/- 9.9 s; P > 0.05). The LMA was inserted more rapidly in patients in the propofol group (74 +/- 29 vs 127 +/- 35 s; P < 0.01) and required fewer attempts (1.2 vs 1.6; P < 0.05) than the sevoflurane group. There was a greater incidence of initially impossible mouth opening in the sevoflurane group (45% vs 21%; P < 0.05). Once mouth opening was possible, the degree of attenuation of laryngeal reflexes was similar. The overall incidence of complications related to LMA insertion, especially apnea (32% vs 0%; P < 0.01), was more frequent in the propofol group (82% vs 26%; P < 0.01). There were four failures of LMA insertion in the propofol group and none in the sevoflurane group. Both groups had stable hemodynamic profiles and good patient satisfaction. We conclude that sevoflurane vital capacity breath induction compares favorably with i.v. propofol induction for LMA insertion in adults. However, prolonged jaw tightness after the sevoflurane induction of anesthesia may delay LMA insertion. IMPLICATIONS: In this randomized, controlled trial, we compared the ease of insertion of the laryngeal mask airway in adults after induction of anesthesia with either a sevoflurane vital capacity breath technique or propofol i.v.. We conclude that sevoflurane compares favorably with propofol, although prolonged jaw tightness may delay laryngeal mask airway insertion.

Adult↗

PubMed1999

Acupuncture treatment at Ang Mo Kio Community Hospital--a report on our initial experience.

BACKGROUND: We report our initial experience with acupuncture treatment at the Ang Mo Kio Community Hospital's Acupuncture Research Clinic. PATIENTS: One thousand one hundred and twenty-eight patients received a total of 12,172 acupuncture treatment sessions during the period between September 1995 and December 1996. The majority were Chinese (94%), between 40-70 years (70%) with either dialect or Mandarin (68%) as the main spoken language. However, one third of the patients were English speaking, and educational level did not seem to be a factor among our patients accepting acupuncture treatment. Most had either painful conditions (58%) or stroke-related dysfunction (23%). Amongst the painful conditions, arthritis (25%), low back pain (22%) and other musculo-skeletal pain (12%) were the most common. RESULTS: Prior to treatment, about three-quarter of patients believed acupuncture would benefit them while 40% had tried acupuncture before. After completion of treatment, 70% of all patients considered acupuncture safe, 54% were satisfied with the overall result, 51% felt acupuncture was beneficial, while 54% would recommend acupuncture to others with similar conditions. In a subgroup of patients treated for painful conditions, > 90% reported improvement. Near-syncope occurred in 2 patients (0.18%) or during 2 treatment sessions (0.02%). There was no other acupuncture-related complication. CONCLUSION: Our preliminary experience showed that acupuncture is safe, and appears to be beneficial to patients with painful conditions. An overview of acupuncture treatment is presented, and the issues of safety, efficacy and a need to conduct randomised controlled clinical trials are discussed.

Acupuncture Therapy↗

PubMed1999

The effect of propofol on human gastric and colonic muscle contractions.

UNLABELLED: Although propofol is widely used for sedation in the intensive care unit, there are limited data on its effects on gastrointestinal motility. For that reason, we studied the in vitro effects of propofol on human gastric and colonic smooth muscle. Grossly normal human gastric and colonic muscle strips were mounted in an organ bath set-up for isometric contraction and stimulated by acetylcholine (Ach), using a cumulative dose schedule in the absence or presence of different concentrations of propofol [1.7 x 10(-6) M (0.3 microg/mL) to 4.4 x 10(-4) M (78 microg/mL)]. Ach led to concentration-dependent contraction of both gastric and colonic muscle strips, whereas propofol, at a concentration 6.7 x 10(-6) M (1.2 microg/mL) and above, significantly depressed Ach-induced contraction in a concentration-dependent manner for both smooth muscle preparations. In addition, propofol, at a concentration 2.7 x 10(-5)M (4.8 microg/mL) and above, depressed spontaneous contractile activity of both smooth muscle preparations. Fat emulsion 10% (Intralipid), the solvent for propofol, had no effect on either the spontaneous activity or the Ach-induced contraction of gastric and colonic smooth muscles. IMPLICATIONS: The success of enteral feeding requires a normal gastrointestinal motility. We found that, at clinically relevant concentrations, propofol impaired gastrointestinal contractile activity. Further investigations are required to determine the clinical significance of this change.

Acetylcholine↗

PubMed1998

Activation of beta3-adrenoceptors by exogenous dopamine to lower glucose uptake into rat adipocytes.

The effect of dopamine hydrochloride on beta3-adrenoceptors was studied in isolated adipocytes of Wistar rats using uptake of [14C]-deoxy-D-glucose (2-DG) as the indicator. Dopamine induced a concentration-dependent decrease of 2-DG uptake into adipocytes in a manner which was not modified by haloperidol at concentrations sufficient to block dopaminergic receptors. Failure of blockade was also observed in samples receiving the pretreatment with a mixture of SCH23390 and domperidone, the dopaminergic antagonists. Absence of dopaminergic receptors in rat white adipocytes was further supported by the findings that dopaminergic agonists did not modify the glucose uptake and the negative response to receptor antibodies in immunoblotting analysis. Pindolol and propranolol reversed this inhibition of dopamine in a concentration-dependent manner. However, this action of dopamine was not affected by prazosin at concentrations sufficient to block alpha-adrenoceptors. Effect of dopamine was reduced in the presence of Rp-cyclic AMPS triethylamine, the membrane-permeable antagonist of cyclic AMP (cAMP), indicating the mediation of cAMP in this inhibition. Direct effect of exogenous dopamine on beta3-adrenoceptors was identified using the antibody for beta3-adrenoceptors that reversed the inhibition of dopamine. These results suggest that dopamine can activate beta3-adrenoceptors to lower glucose uptake into rat white adipocytes which lack dopaminergic receptors.

Adipocytes↗