FMO3-TMAO axis modulates the clinical outcome in chronic heart-failure patients with reduced ejection fraction: evidence from an Asian population / 医学前沿

The association among plasma trimethylamine-N-oxide (TMAO), FMO3 polymorphisms, and chronic heart failure (CHF) remains to be elucidated. TMAO is a microbiota-dependent metabolite from dietary choline and carnitine. A prospective study was performed including 955 consecutively diagnosed CHF patients with reduced ejection fraction, with the longest follow-up of 7 years. The concentrations of plasma TMAO and its precursors, namely, choline and carnitine, were determined by liquid chromatography-mass spectrometry, and the FMO3 E158K polymorphisms (rs2266782) were genotyped. The top tertile of plasma TMAO was associated with a significant increment in hazard ratio (HR) for the composite outcome of cardiovascular death or heart transplantation (HR = 1.47, 95% CI = 1.13-1.91, P = 0.004) compared with the lowest tertile. After adjustments of the potential confounders, higher TMAO could still be used to predict the risk of the primary endpoint (adjusted HR = 1.33, 95% CI = 1.01-1.74, P = 0.039). This result was also obtained after further adjustment for carnitine (adjusted HR = 1.33, 95% CI = 1.01-1.74, P = 0.039). The FMO3 rs2266782 polymorphism was associated with the plasma TMAO concentrations in our cohort, and lower TMAO levels were found in the AA-genotype. Thus, higher plasma TMAO levels indicated increased risk of the composite outcome of cardiovascular death or heart transplantation independent of potential confounders, and the FMO3 AA-genotype in rs2266782 was related to lower plasma TMAO levels.

Function analysis of anthocyanidin synthase from Morus alba L. by expression in bacteria and tobacco

Background: Flavonoids are a kind of important secondary metabolite and are commonly considered to provide protection to plants against stress and UV-B for a long time. Anthocyanidin synthase (ANS), which encodes a dioxygenase in the flavonoid pathway, catalyzes the conversion of leucoanthocyanidins to anthocyanidins, but there is no direct evidence indicating that it provides tolerance to stress in plants. Results: To investigate whether ANS can increase tolerance to abiotic stress, MaANS was isolated from mulberry fruits and transformed into tobacco. Our results suggested that the bacterially expressed MaANS protein can convert dihydroquercetin to quercetin. Overexpression of MaANS remarkably increased the accumulation of total flavonoids in transgenic lines and anthocyanins in corollas of flowers. Transgenic lines showed higher tolerance to NaCl and mannitol stress. Conclusions: These results indicated that MaANS participates in various dioxygenase activities, and it can protect plants against abiotic stress by improving the ROS-scavenging ability. Thus, this alternative approach in crop breeding can be considered in the improvement of stress tolerance by enriching flavonoid production in plants

Genetic polymorphism of FMO3 and its role in drug metabolism and toxicity / 中国中药杂志

The flavin-containing monooxygenase 3 (FMO3) is an important hepatic microsomal enzyme. Numerous mutations of FMO3 gene have been reported, and polymorphic varients of the gene have been identified. Several studies indicated that variability in the expression of FMO3 involved in some nitrogen, or sulfur-containing durg metabolism. This review summarizes the genetic polymorphism of FMO3 and its role in drug metabolism and toxicity.

Nonconserved hinge in Baeyer-Villiger monooxygenase affects catalytic activity and stereoselectivity / 生物工程学报

Baeyer-Villiger monooxygenases (BVMOs) are important biocatalysts to synthesize a series of valuable esters and lactones. Based on protein sequence alignment and crystal structure analysis, a nonconserved hinge which linked NADPH domain and FAD domain was speculated to play an important role in substrate recognition and catalytic oxidation process. Cyclohexanone monooxygenase (CHMO) was selected as a model. Mutants obtained by homologous replacement of the whole hinge almost completely lost its original catalytic activity, demonstrating that the overall hinge structure was of great importance. Some significant sites were identified to greatly affect the catalytic activity and stereoselectivity by alanine scanning mutagenesis, accompanied by enzyme activity assessments and chiral kinetic resolutions. Altering K153 decreased the activity of the enzyme but enhanced the stereoselectivity. Changing L143 site reduced stereoselectivity but had little effect on enzyme activity. Mutation at L144 site dramatically weakened both activity and stereoselectivity. Subsequently, these corresponding sites in phenylacetone monooxygenase were also illustrated to follow a similar rule, revealing a universal importance of these sites in the BVMO family. These results expanded our understanding of the structure-activity relationship of these enzymes and provided more proofs for future directed evolution of BVMOs.

Advances in biomolecular machine: methane monooxygenases / 生物工程学报

Methane monooxygenases (MMO), regarded as "an amazing biomolecular machine", catalyze the oxidation of methane to methanol under aerobic conditions. MMO catalyze the oxidation of methane elaborately, which is a novel way to catalyze methane to methanol. Furthermore, MMO can inspire the biomolecular machine design. In this review, we introduced MMO including structure, gene and catalytic mechanism. The history and the taxonomy of MMO were also introduced.

Phospholipid Remodeling and Eicosanoid Signaling in Colon Cancer Cells.

Phospholipid remodeling and eicosanoid synthesis are central to lipid-based inflammatory reactions. Studies have revealed that membrane phospholipid remodeling by fatty acids through deacylation/reacylation reactions increases the risk of colorectal cancers (CRC) by allowing the cells to produce excess inflammatory eicosanoids, such as prostaglandins, thromboxanes and leukotrienes. Over the years, efforts have been made to understand the lipid remodeling pathways and to design anti-cancer drugs targeting the enzymes of eicosanoid biosynthesis. Here, we discuss the recent progress in phospholipid remodeling and eicosanoid biosynthesis in CRC.

Instituto de Radium de Minas Gerais: vanguarda da radioterapia no Brasil, 1923-1935 / Minas Gerais Radium Institute: at the forefront of radiotherapy in Brazil, 1923-1935

Este artigo propõe estudar os primeiros 12 anos de existência do Instituto de Radium de Minas Gerais, fundado em 1922. Sua atuação na luta contra o câncer no Brasil, ainda pouco conhecida, começa a ser esboçada pelo estudo de documentação institucional inédita. Através de um banco de dados elaborado com informações constantes em seu livro de registro de pacientes, foram feitos levantamentos estatísticos dos tipos de câncer e das formas de tratamento existentes entre 1923 e 1935. Esse livro faz parte de um conjunto de outros cinco recentemente descobertos no Centro de Memória da Medicina/UFMG. A documentação permite resgatar os primórdios das intervenções de radioterapia no país e acompanhar seu desenvolvimento e a influência exercida por esse hospital modelo.

This article proposes to study the first 12 years of the Minas Gerais Radium Institute, founded in 1922. Its work in the fight against cancer in Brazil, albeit still little known, is coming to light as its institutional documents are studied. A database has been prepared using information from its patient register, based on which statistical analyses have been done to identify the types of cancer and treatments available there between 1923 and 1935. This register is one of five recently unearthed at the Medicine Memory Center of the Universidade Federal de Minas Gerais. Through them, the earliest experiments in radiotherapy in Brazil can be reconstituted, and its development and the influence of this model hospital can be mapped out.

Temporomandibular Disorders in a Sample Population of the Brazilian Northeast

Temporomandibular disorder (TMD) is a common condition. This study is part of a research group and it investigated the prevalence of TMD and myofascial pain and its association with gender, age and socioeconomic class. The sample comprised 100 subjects, aged 15 to 70, users of the Family Health Units' services, in the city of Recife, PE, Brazil. The TMD degree was evaluated using the Research Diagnostic Criteria for TMD and socioeconomic class by the Economic Classification Criteria Brazil. Categorical variables were analyzed by chi-square test for proportions and Fisher's exact test for 2x2 tables, and binary logistic analysis to track the relationship between the independent and dependent variables. According to the results, 42% of the subjects had TMD and 14% myofascial pain. No statistically significant association could be found between TMD and gender or socioeconomic class, but it was found to have statistically significant association with age, and myofascial pain was associated with socioeconomic class. Considering that the results of the present study should be confirmed by further studies and the fact that this was a pilot study, the prevalence must be analyzed with caution.

Disfunção temporomandibular (DTM) é uma condição comum. Este estudo é parte de um grupo de pesquisa e investigou a prevalência de DTM e dor miofascial e suas associações com sexo, idade e classe socioeconômica. A amostra foi composta por 100 indivíduos, com idades entre 15 e 70 anos, usuários das Unidades de Saúde da Família, na cidade de Recife, PE. O grau de DTM foi avaliado usando os Critérios de Diagnósticos Científicos em DTM, e classe socioeconômica com o Critério de Classificação Econômica Brasil. As variáveis categóricas foram analisadas pelo teste do qui-quadrado para proporções e teste exato de Fisher para tabelas 2x2, e a análise logística binária para traçar a relação entre as variáveis independentes e dependentes. De acordo com os resultados, 42% dos indivíduos tinham DTM e 14% dor miofascial. Não houve associação estatisticamente significativa entre DTM e sexo ou classe socioeconômica, mas houve associação estatisticamente significativa com a idade e a dor miofascial foi associada com a classe socioeconômica. Considerando-se que os resultados do presente estudo devam ser confirmados em outros estudos e por causa de sua natureza piloto, a prevalência deve ser analisada com cautela.

Advances in degradation of chlorinated hydrocarbons by obligate and facultative methanotrophs / 生物工程学报

Bioremediation is one of the most effective ways to treat and dispose of chlorinated hydrocarbons, and methanotrophs are potentially useful to do so. Recent studies found that facultative methanotrophs can use compounds containing C-C bond as sources of carbon and energy, thus overcoming the limitation that obligate methanotrophsone uses only C1 compounds for this process. This is a unique metabolic approach that is becoming increasingly attractive in the field of contaminant biodegradation. Here, we summarized the bioremediation of chlorinated hydrocarbons by obligate and facultative methanotrophs. This process involves the degradation of various chlorinated hydrocarbons by diverse strains, including pure cultures and mixed cultures. We also compare the activity expression and catalytic properties of different types of methane monooxygenases in various substrates. We furthermore summarize the kinetic characteristics of the degradation of chlorinated hydrocarbons using the model strain Methylosinus trichosporium OB3b, and outline the degradation and potential of chlorinated hydrocarbons by facultative methanotrophs. Lastly, we discuss current problems and future research directions for degradation of chlorinated hydrocarbons by methanotrophs.

Sequence analysis of 16S rDNA and pmoCAB gene cluster of trichloroethylene-degrading methanotroph / 生物工程学报

Methanotrophs could degrade methane and various chlorinated hydrocarbons. The analysis on methane monooxygenase gene cluster sequence would help to understand its catalytic mechanism and enhance the application in pollutants biodegradation. The methanotrophs was enriched and isolated with methane as the sole carbon source in the nitrate mineral salt medium. Then, five chlorinated hydrocarbons were selected as cometabolic substrates to study the biodegradation. The phylogenetic tree of 16S rDNA using MEGE5.05 software was constructed to identify the methanotroph strain. The pmoCAB gene cluster encoding particulate methane monooxygenase (pMMO) was amplified by semi-nested PCR in segments. ExPASy was performed to analyze theoretical molecular weight of the three pMMO subunits. As a result, a strain of methanotroph was isolated. The phylogenetic analysis indicated that the strain belongs to a species of Methylocystis, and it was named as Methylocystis sp. JTC3. The degradation rate of trichloroethylene (TCE) reached 93.79% when its initial concentration was 15.64 μmol/L after 5 days. We obtained the pmoCAB gene cluster of 3 227 bp including pmoC gene of 771 bp, pmoA gene of 759 bp, pmoB gene of 1 260 bp and two noncoding sequences in the middle by semi-nested PCR, T-A cloning and sequencing. The theoretical molecular weight of their corresponding gamma, beta and alpha subunit were 29.1 kDa, 28.6 kDa and 45.6 kDa respectively analyzed using ExPASy tool. The pmoCAB gene cluster of JTC3 was highly identical with that of Methylocystis sp. strain M analyzed by Blast, and pmoA sequences is more conservative than pmoC and pmoB. Finally, Methylocystis sp. JTC3 could degrade TCE efficiently. And the detailed analysis of pmoCAB from Methylocystis sp. JTC3 laid a solid foundation to further study its active sites features and its selectivity to chlorinated hydrocarbon.

Protective Effects of Inducible HO-1 on Oxygen Toxicity in Rat Brain Endothelial Microvessel Cells

BACKGROUND: Reperfusion in ischemia is believed to generate cytotoxic oxidative stress, which mediates reperfusion injury. These stress conditions can initiate lipid peroxidation and damage to proteins, as well as promote DNA strand breaks. As biliverdin and bilirubin produced by heme oxygenase isoform 1 (HO-1) have antioxidant properties, the production of both antioxidants by HO-1 may help increase the resistance of the ischemic brain to oxidative stress. In the present study, the survival effect of HO-1 was confirmed using hemin. METHODS: To confirm the roles of HO-1, carbon monoxide, and cyclic guanosine monophosphate further in the antioxidant effect of HO-1 and bilirubin, cells were treated with cycloheximide, desferoxamine, and zinc deuteroporphyrin IX 2,4 bis glycol, respectively. RESULTS: HO-1 itself acted as an antioxidant. Furthermore, iron, rather than carbon monoxide, was involved in the HO-1-mediated survival effect. HO-1 activity was also important in providing bilirubin as an antioxidant. CONCLUSION: Our results suggested that HO-1 helped to increase the resistance of the ischemic brain to oxidative stress.

Halotolerance, ligninase production and herbicide degradation ability of basidiomycetes strains

Fungi have been recently recognized as organisms able to grow in presence of high salt concentration with halophilic and halotolerance properties and their ligninolytic enzyme complex have an unspecific action enabling their use to degradation of a number of xenobiotic compounds. In this work, both the effect of salt and polyols on growth of the basidiomycetes strains, on their ability to produce ligninolytic enzyme and diuron degradation were evaluated. Results showed that the presence of NaCl in the culture medium affected fungal specimens in different ways. Seven out of ten tested strains had growth inhibited by salt while Dacryopinax elegans SXS323, Polyporus sp MCA128 and Datronia stereoides MCA167 fungi exhibited higher biomass production in medium containing 0.5 and 0.6 mol.L-1 of NaCl, suggesting to be halotolerant. Polyols such as glycerol and mannitol added into the culture media improved the biomass and ligninases production by D. elegans but the fungus did not reveal consumption of these polyols from media. This fungus degraded diuron in medium control, in presence of NaCl as well as polyols, produced MnP, LiP and laccase.

Improved extraction of solanesol from tobacco waste by enzymatic cell wall breaking / 生物工程学报

To improve the extraction of solanesol from tobacco waste, we developed an enzymatic cell wall-breaking process with combined cellulase and ligninase. The effects of reaction time, temperature, pH and enzyme/substrate ratio were determined. The results show that the catalytic effect was better than either single enzyme when the ratio of cellulase to ligninase was 15:1 (U/U). Under the optimized conditions of 175 U/g (enzymes/substrate), tobacco to water 1:5 (W/W), temperature 40 degrees C and pH 6.0, the concentration of solanesol in the solution could reach 0.33 g/L after 8 h. And the average leaching rate reached 96.53% which was 1.68 times of the extraction methods of chemical reflux. It provides new way for the extraction of solanesol from tobacco waste, and worthwhile to be further explored.

The hybrid perventricular closure of apical muscular ventricular septal defect with Amplatzer duct occluder / 소아과

PURPOSE: Apical muscular ventricular septal defects (MVSDs), especially in small infants, can be difficult to manage using surgical and percutaneous closure. An intraoperative perventricular procedure is a good option for closing apical MVSDs in small children with or without associated cardiac anomalies. We evaluated the results of hybrid perventricular closure of apical MVSDs performed using an Amplatzer duct occluder (ADO). METHODS: We retrospectively reviewed the medical records of 5 patients who underwent hybrid perventricular closure of MVSDs with ADOs, from March 2006 to May 2011. The median patient age at the time of the procedure was 12 months (range, 25 days to 25 months), and the median body weight was 9.1 kg (range, 4.3 to 15 kg). Two patients had multiple ventricular septal defects (VSDs; additional perimembranous VSD in 1 patient and multiple MVSDs in the other) and 3 patients had associated cardiac anomalies; complete transposition of the great arteries in 1 patient and an atrial septal defect in 2 patients. All the procedures were performed on beating hearts, exception in 1 case. The ADO selected for the aortic side was at least 1 to 2 mm larger than the largest VSD in the left ventricle side. RESULTS: The procedure was successful in all patients and each device was well positioned. During the median follow-up of 2.4 years, a small residual VSD was noted in 2 patients who had multiple VSDs and no leakage was seen in the other 3 patients. CONCLUSION: Perventricular closure of MVSD with an ADO is a good option for patients with apical MVSD. However, careful manipulation is important, especially in the case of small infants.

A choline monooxygenase gene promoter from Salicornia europaea increases expression of the -glucuronidase gene under abiotic stresses in tobacco (Nicotiana tabacum L.).

A 1312 bp 5' flanking region of Salicornia europaea choline monooxygenase (SeCMO) gene was isolated using the anchored PCR. To investigate the mechanism of regulation for this stress-induced gene, the SeCMO promoter--glucuronidase (GUS) chimeric gene constructs containing five deletions F1, F2, F3, F4 and F5 were introduced into tobacco (Nicotiana tabacum L.) by Agrobacterium-mediated transformation. The functional properties of each promoter fragment were examined by assaying GUS activity in the leaves of transgenic tobacco treated with abiotic stresses (NaCl, PEG6000 and low temperature). The GUS activity in transgenic tobacco with F2 (-1056 to +8) construct showed highest increase under all the three abiotic stresses. Thus, the study provided a potential promoter induced by the salt, dehydration and cold for the plant genetic manipulation.

Detection of Extracellular Enzyme Activities in Ganoderma neo-japonicum

The ability of Ganoderma to produce extracellular enzymes, including beta-glucosidase, cellulase, avicelase, pectinase, xylanase, protease, amylase, and ligninase was tested in chromogenic media. beta-glucosidase showed the highest activity, among the eight tested enzymes. In particular, Ganoderma neo-japonicum showed significantly stronger activity for beta-glucosidase than that of the other enzymes. Two Ganoderma lucidum isolates showed moderate activity for avicelase; however, Ganoderma neo-japonicum showed the strongest activity. Moderate ligninase activity was only observed in Ganoderma neo-japonicum. In contrast, pectinase, amylase, protease, and cellulase were not present in Ganoderma. The results show that the degree of activity of the tested enzymes varied depending on the Ganoderma species tested.

Isolation of choline monooxygenase (CMO) gene from Salicornia europaea and enhanced salt tolerance of transgenic tobacco with CMO genes.

Glycinebetaine (GB) is an osmoprotectant accumulated by certain plants in response to high salinity, drought, and cold stress. Plants synthesize GB via the pathway choline → betaine aldehyde → glycinebetaine, and the first step is catalyzed by choline monooxygenase (CMO). In the present study, by using RT-PCR and RLM-RACE, a full-length CMO cDNA (1844 bp) was cloned from a halophyte Salicornia europaea, which showed high homology to other known sequences. In order to identify its function, the ORF of CMO cDNA was inserted into binary vector PBI121 to construct the chimeric plant expression vector PBI121-CMO. Using Agrobacterium (LBA4404) mediation, the recombinant plasmid was transferred into tobacco (Nicotiana tabacum). The PCR, Southern blot and RT-PCR analysis indicated the CMO gene was integrated into the tobacco genome, as well as expressed on the level of transcription. The transgenic tobacco plants were able to survive on MS medium containing 300 mmol/L NaCl and more vigorous than those of wild type with the same concentration salt treatment. In salt-stress conditions, transgenic plants had distinctly higher chlorophyll content and betaine accumulation than that of the control, while relative electrical conductivity of transgenic plants was generally lower. The results suggested the CMO gene transformation could effectively contribute to improving tobacco salt-resistance.

Interação entre antioxidantes naturais e espécies reativas do oxigênio nas doenças cardiovasculares: perspectivas para a contribuição do alecrim (Rosmarinus officinalis L. ) / Interaction between natural antioxidants and reactive oxygen species in cardiovascular diseases: perspectives to rosemary (Rosmarinus offi cinalis L. ) contribution

The association between high levels of LDL cholesterol and oxidative stressis the on set of the atherosclerotic process. Oxidative stress, verified by the significant increase in the concentration of reactive oxygen species, causes damage to the endothelial wall and leads to LDL oxidation, which in turn will be deposited as fatty cells leading to the obstruction of vessels and arteries. In vascular cells a lot of enzymes have been described as potential sources of ROS; however, enzymatic and non enzymatic mecanisms protect the organism against such species. Among non enzymatic antioxidants there are substances derived from foods such as vitamins and phenolic compounds, which have been receiving increasing attentiondue to their chemopreventive function against oxidative damages. Rosemary (Rosmarinus offi cinalis L.) belongs to the Labiatae family, the antioxidant properties of which have been attributed to a variety of phenolic compounds capable of reacting with free radicals and quench ROS. Studies have revealed that rosemary could be an important compound in antiglycative therapy, helping in the prevention and treatment of chronic-degenerative diseases, reinforcing the need of new researches to elucidate its antioxidant contribution in vivo.

La asociación entre niveles elevados de colesterol LDL y el estrés oxidativo compone el inicio del proceso arteriosclerótico y contribuye para el desarrollo de enfermedades cardiovasculares. El estrés oxidativo, determinado por el aumento significativo de la concentración de especies reactivas del oxígeno (EROS), produce daños en la pared endotelial y oxidación de las LDL queserán depositadas como células grasas provocando la obstrucción de vasos y arterias. En las células vasculares muchas enzimas hansido descritas como fuentes potenciales de EROS, pero mecanismos enzimáticos y no enzimáticos protegen el organismo contra esas especiesreactivas. Entre los antioxidantes no enzimáticos hay sustancias derivadas de los alimentos comolas vitaminas y los compuestos fenólicos, los cuales han recibido una gran atención debidoa sus propiedades quimio preventivas contra el daño oxidativo. El romero (Rosmarinus offi cinalisL.) pertenece a la familia Labiatae cuyas propiedades antioxidantes han sido atribuidasa una variedad de compuestos fenólicos capacesde reaccionar con los radicales libres y eliminarlas EROS. Estudios han revelado que el romero puede ser un elemento importante en el combatea la oxidación glicativa, auxiliando en la prevención y tratamiento de las enfermedades degenerativas crónicas y reforzando la necesidadde aumentar las investigaciones para dilucidarsu contribución antioxidante in vivo.

A associação entre níveis elevados de LDL colesterol e o estresse oxidativo constituem o início do processo aterosclerótico e contribuem para o desenvolvimento das doenças cardiovasculares. O estresse oxidativo, verifica do pelo aumento significativo da concentração de espécies reativas de oxigênio (EROS), causa danos na parede endotelial e leva à oxidação das partículas de LDL, que por sua vez serão depositadas como células gordurosas levando à obstrução dos vasos e artérias. Nas células vasculares, muitas enzimas têm sido descritas como fontes potenciais de EROS, contudo mecanismos enzimáticos e não-enzimáticos protegem o organismo contra tais espécies reativas. Dentre os antioxidantes não enzimáticos encontram-se substâncias derivadas de alimentos como vitaminas e compostos fenólicos, os quais têm recebido crescente atenção devido às suas funções quimio preventivas contra o dano oxidativo. O alecrim (Rosmarinus officinalis L.) é um membro da família Labiatae, cujas propriedades antioxidantes têm sido atribuídas a uma variedade de compostos fenólicos capazes de reagir com radicais livres e eliminar as EROS. Estudos relatam que o alecrim pode ser um componente importante na terapia antiglicativa, auxiliando na prevenção e no tratamento de doenças crônico-degenerativas, reforçando a necessidade de novas pesquisas para elucidar sua contribuição antioxidante in vivo.

Alveolar Bone Distraction Osteogenesis at Maxillary Anterior Region for Forward-Downward Movement

Regulation of Adenosine-activated GIRK Channels by Gq-coupled Receptors in Mouse Atrial Myocytes

Adenosine (Ado) is an important mediator of the endogenous defense against ischemia-induced injury in the heart. The action of Ado is mediated by activation of G protein-gated inwardly rectifying K+ (GIRK) channels. In turn, GIRK channels are inhibited by reducing phosphatidylinositol 4,5-bisphosphate (PIP2) through Gq protein-coupled receptors (GqPCRs). We previously found that GIRK channels activated by acetylcholine, a muscarinic M2 acetylcholine receptor agonist, are inhibited by GqPCRs in a receptor-specific manner. However, it is not known whether GIRK channels activated by Ado signaling are also regulated by GqPCRs. Presently, this was investigated in mouse atrial myocytes using the patch clamp technique. GIRK channels were activated by 100 micrometer Ado. When Ado was repetitively applied at intervals of 5~6 min, the amplitude of second Ado-activated GIRK currents (I(K(Ado))) was 88.3+/-3.7% of the first I(K(Ado)) in the control. Pretreatment of atrial myocytes with phenylephrine, endothelin-1, or bradykinin prior to a second application of Ado reduced the amplitude of the second I(K(Ado)) to 25.5+/-11.6%, 30.5+/-5.6%, and 96.0+/-2.7%, respectively. The potency of I(K(Ado)) inhibition by GqPCRs was different with that observed in acetylcholine-activated GIRK currents (I(K(ACh))) (endothelin-1>phenylephrine>bradykinin). I(K(Ado)) was almost completely inhibited by 500 micrometer of the PIP2 scavenger neomycin, suggesting low PIP2 affinity of I(K(Ado)). Taken together, these results suggest that the crosstalk between GqPCRs and the Ado-induced signaling pathway is receptor-specific. The differential change in PIP2 affinity of GIRK channels activated by Ado and ACh may underlie, at least in part, their differential responses to GqPCR agonists.