New Evidence on BPA's Role in Adipose Tissue Development of Proinflammatory Processes and Its Relationship with Obesity.

Bisphenol A (BPA) is a xenobiotic with endocrine disruptor properties which interacts with various receptors, eliciting a cellular response. In the plastic industry, BPA is widely used in the production of polycarbonate and epoxy-phenolic resins to provide elastic properties. It can be found in the lining of canned foods, certain plastic containers, thermal printing papers, composite dental fillings, and medical devices, among other things. Therefore, it is a compound that, directly or indirectly, is in daily contact with the human organism. BPA is postulated to be a factor responsible for the global epidemic of obesity and non-communicable chronic diseases, belonging to the obesogenic and diabetogenic group of compounds. Hence, this endocrine disruptor may be responsible for the development of metabolic disorders, promoting in fat cells an increase in proinflammatory pathways and upregulating the expression and release of certain cytokines, such as IL6, IL1ß, and TNFα. These, in turn, at a systemic and local level, are associated with a chronic low-grade inflammatory state, which allows the perpetuation of the typical physiological complications of obesity.

Improving Lurasidone Hydrochloride's Solubility and Stability by Higher-Order Complex Formation with Hydroxypropyl-ß-cyclodextrin.

The biopharmaceutical classification system groups low-solubility drugs into two groups: II and IV, with high and low permeability, respectively. Most of the new drugs developed for common pathologies present solubility issues. This is the case of lurasidone hydrochloride-a drug used for the treatment of schizophrenia and bipolar depression. Likewise, the stability problems of some drugs limit the possibility of preparing them in liquid pharmaceutical forms where hydrolysis and oxidation reactions can be favored. Lurasidone hydrochloride presents the isoindole-1,3-dione ring, which is highly susceptible to alkaline hydrolysis, and the benzisothiazole ring, which is susceptible to a lesser extent to oxidation. Herein, we propose to study the increase in the solubility and stability of lurasidone hydrochloride by the formation of higher-order inclusion complexes with hydroxypropyl-ß-cyclodextrin. Several stoichiometric relationships were studied at between 0.5 and 3 hydroxypropyl-ß-cyclodextrin molecules per drug molecule. The obtained products were characterized, and their solubility and stability were assessed. According to the obtained results, the formation of inclusion complexes dramatically increased the solubility of the drug, and this increased with the increase in the inclusion ratio. This was associated with the loss of crystalline state of the drug, which was in an amorphous state according to infrared spectroscopy, calorimetry, and X-ray analysis. This was also correlated with the stabilization of lurasidone by the cyclodextrin inhibiting its recrystallization. Phase solubility,1H-NMR, and docking computational characterization suggested that the main stoichiometric ratio was 1:1; however, we cannot rule out a 1:2 ratio, where a second cyclodextrin molecule could bind through the isoindole-1,3-dione ring, improving its stability as well. Finally, we can conclude that the formation of higher-order inclusion complexes of lurasidone with hydroxypropyl-ß-cyclodextrin is a successful strategy to increase the solubility and stability of the drug.

Specialized Proresolving Lipid Mediators: A Potential Therapeutic Target for Atherosclerosis.

Cardiovascular disease (CVD) is a global public health issue due to its high morbidity, mortality, and economic impact. The implementation of innovative therapeutic alternatives for CVD is urgently required. Specialized proresolving lipid mediators (SPMs) are bioactive compounds derived from ω-3 and ω-6 fatty acids, integrated into four families: Lipoxins, Resolvins, Protectins, and Maresins. SPMs have generated interest in recent years due to their ability to promote the resolution of inflammation associated with the pathogeneses of numerous illnesses, particularly CVD. Several preclinical studies in animal models have evidenced their ability to decrease the progression of atherosclerosis, intimal hyperplasia, and reperfusion injury via diverse mechanisms. Large-scale clinical trials are required to determine the effects of SPMs in humans. This review integrates the currently available knowledge of the therapeutic impact of SPMs in CVD from preclinical and clinical studies, along with the implicated molecular pathways. In vitro results have been promising, and as such, SPMs could soon represent a new therapeutic alternative for CVD.

New Insights on the Role of Connexins and Gap Junctions Channels in Adipose Tissue and Obesity.

Due to the inability to curb the excessive increase in the prevalence of obesity and overweight, it is necessary to comprehend in more detail the factors involved in the pathophysiology and to appreciate more clearly the biochemical and molecular mechanisms of obesity. Thus, understanding the biological regulation of adipose tissue is of fundamental relevance. Connexin, a protein that forms intercellular membrane channels of gap junctions and unopposed hemichannels, plays a key role in adipogenesis and in the maintenance of adipose tissue homeostasis. The expression and function of Connexin 43 (Cx43) during the different stages of the adipogenesis are differentially regulated. Moreover, it has been shown that cell-cell communication decreases dramatically upon differentiation into adipocytes. Furthermore, inhibition of Cx43 degradation or constitutive overexpression of Cx43 blocks adipocyte differentiation. In the first events of adipogenesis, the connexin is highly phosphorylated, which is likely associated with enhanced Gap Junction (GJ) communication. In an intermediate state of adipocyte differentiation, Cx43 phosphorylation decreases, as it is displaced from the membrane and degraded through the proteasome; thus, Cx43 total protein is reduced. Cx is involved in cardiac disease as well as in obesity-related cardiovascular diseases. Different studies suggest that obesity together with a high-fat diet are related to the production of remodeling factors associated with expression and distribution of Cx43 in the atrium.

Specialized Pro-Resolving Lipid Mediators: The Future of Chronic Pain Therapy?

Chronic pain (CP) is a severe clinical entity with devastating physical and emotional consequences for patients, which can occur in a myriad of diseases. Often, conventional treatment approaches appear to be insufficient for its management. Moreover, considering the adverse effects of traditional analgesic treatments, specialized pro-resolving lipid mediators (SPMs) have emerged as a promising alternative for CP. These include various bioactive molecules such as resolvins, maresins, and protectins, derived from ω-3 polyunsaturated fatty acids (PUFAs); and lipoxins, produced from ω-6 PUFAs. Indeed, SPMs have been demonstrated to play a central role in the regulation and resolution of the inflammation associated with CP. Furthermore, these molecules can modulate neuroinflammation and thus inhibit central and peripheral sensitizations, as well as long-term potentiation, via immunomodulation and regulation of nociceptor activity and neuronal pathways. In this context, preclinical and clinical studies have evidenced that the use of SPMs is beneficial in CP-related disorders, including rheumatic diseases, migraine, neuropathies, and others. This review integrates current preclinical and clinical knowledge on the role of SPMs as a potential therapeutic tool for the management of patients with CP.

An Update on Connexin Gap Junction and Hemichannels in Diabetic Retinopathy.

Diabetic retinopathy (DR) is one of the main causes of vision loss in the working age population. It is characterized by a progressive deterioration of the retinal microvasculature, caused by long-term metabolic alterations inherent to diabetes, leading to a progressive loss of retinal integrity and function. The mammalian retina presents an orderly layered structure that executes initial but complex visual processing and analysis. Gap junction channels (GJC) forming electrical synapses are present in each retinal layer and contribute to the communication between different cell types. In addition, connexin hemichannels (HCs) have emerged as relevant players that influence diverse physiological and pathological processes in the retina. This article highlights the impact of diabetic conditions on GJC and HCs physiology and their involvement in DR pathogenesis. Microvascular damage and concomitant loss of endothelial cells and pericytes are related to alterations in gap junction intercellular communication (GJIC) and decreased connexin 43 (Cx43) expression. On the other hand, it has been shown that the expression and activity of HCs are upregulated in DR, becoming a key element in the establishment of proinflammatory conditions that emerge during hyperglycemia. Hence, novel connexin HCs blockers or drugs to enhance GJIC are promising tools for the development of pharmacological interventions for diabetic retinopathy, and initial in vitro and in vivo studies have shown favorable results in this regard.

Antimicrobial and Antibiofilm Capacity of Chitosan Nanoparticles against Wild Type Strain of Pseudomonas sp. Isolated from Milk of Cows Diagnosed with Bovine Mastitis.

Bovine mastitis (BM) is the most prevalent bacterial infection in the livestock sector, affecting the dairy industry greatly. The prevention and treatment of this disease is mainly made via antibiotics, but the increasing antimicrobial resistance of pathogens has affected the efficiency of conventional drugs. Pseudomonas sp. is one of the pathogens involved in this infection. The therapeutic rate of cure for this environmental mastitis-causing pathogen is practically zero, regardless of treatment. Biofilm formation has been one of the main virulence mechanisms of Pseudomonas hence presenting resistance to antibiotic therapy. We have manufactured chitosan nanoparticles (NQo) with tripolyphosphate (TPP) using ionotropic gelation. These NQo were confronted against a Pseudomonas sp. strain isolated from milk samples of cows diagnosed with BM, to evaluate their antimicrobial and antibiofilm capacity. The NQo showed great antibacterial effect in the minimum inhibitory concentrations (MIC), minimum bactericidal concentration (MBC) and disk diffusion assays. Using sub lethal concentrations, NQo were tested for inhibition of biofilm formation. The results show that the nanoparticles exhibited biofilm inhibition and were capable of eradicate pre-existing mature biofilm. These findings indicate that the NQo could act as a potential alternative to antibiotic treatment of BM.

Adipogenesis Regulation and Endocrine Disruptors: Emerging Insights in Obesity.

Endocrine disruptors (EDs) are defined as environmental pollutants capable of interfering with the functioning of the hormonal system. They are environmentally distributed as synthetic fertilizers, electronic waste, and several food additives that are part of the food chain. They can be considered as obesogenic compounds since they have the capacity to influence cellular events related to adipose tissue, altering lipid metabolism and adipogenesis processes. This review will present the latest scientific evidence of different EDs such as persistent organic pollutants (POPs), heavy metals, "nonpersistent" phenolic compounds, triclosan, polybrominated diphenyl ethers (PBDEs), and smoke-derived compounds (benzo -alpha-pyrene) and their influence on the differentiation processes towards adipocytes in both in vitro and in vivo models.

Florfenicol Binding to Molecularly Imprinted Polymer Nanoparticles in Model and Real Samples.

A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop assays similar to the enzyme-linked immunosorbent (ELISA) assay to determine and quantify florfenicol (FF) in real food samples such as liquid milk and salmon muscle is presented here. The nanoMIPs were synthesized by a solid-phase approach with an immobilized FF (template) and characterized using dynamic light scattering, a SPR-2 biosensor system and transmission electron microscopy. Immobilization of nanoMIPs was conducted by preparing a homogenous solution of FF-nanoMIPs in water mixed with polyvinyl alcohol (PVA) 0.2% (w/v) in each well of a microplate. The detection of florfenicol was achieved in competitive binding experiments with a horseradish peroxidase-florfenicol (FF-HRP) conjugate. The assay made it possible to measure FF in buffer and in real samples (liquid milk and salmon muscle) within the range of 60-80 and 90-100 ng/mL, respectively. The immobilized nanoMIPs were stored for six weeks at room temperature and at 5 °C. The results indicate good signal recovery for all FF concentrations in spiked milk samples, without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELISA.

Effect of Oral Nutritional Supplements with Sucromalt and Isomaltulose versus Standard Formula on Glycaemic Index, Entero-Insular Axis Peptides and Subjective Appetite in Patients with Type 2 Diabetes: A Randomised Cross-Over Study.

Oral diabetes-specific nutritional supplements (ONS-D) induce favourable postprandial responses in subjects with type 2 diabetes (DM2), but they have not been correlated yet with incretin release and subjective appetite (SA). This randomised, double-blind, cross-over study compared postprandial effects of ONS-D with isomaltulose and sucromalt versus standard formula (ET) on glycaemic index (GI), insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1) and SA in 16 individuals with DM2. After overnight fasting, subjects consumed a portion of supplements containing 25 g of carbohydrates or reference food. Blood samples were collected at baseline and at 30, 60, 90, 120, 150 and 180 min; and SA sensations were assessed by a visual analogue scale on separate days. Glycaemic index values were low for ONS-D and intermediate for ET (p < 0.001). The insulin area under the curve (AUC0-180 min) (p < 0.02) and GIP AUC (p < 0.02) were lower after ONS-D and higher GLP-1 AUC when compared with ET (p < 0.05). Subjective appetite AUC was greater after ET than ONS-D (p < 0.05). Interactions between hormones, hunger, fullness and GI were found, but not within the ratings of SA; isomaltulose and sucromalt may have influenced these factors.

[Eating behavior and its association with nutritional status and physical activity in a general Chilean population]. / Comportamiento hacia los alimentos y su asociación con el estado nutricional y la actividad física en una población general chilena.

INTRODUCTION: obesity has become a chronic disease whose etiology can be based on an imbalance between the contribution and energy expenditure of the individual, where the behavior against food consumption and physical activity play an important role as determinants in this energy balance. METHODS: in the present study, behavior in relation to food consumption and physical activity and its association with nutritional status in a general Chilean population was analyzed. It was a cross-sectional study in 629 people, belonging to the university community of the Andres Bello University. The subjects answered online surveys about sociodemographic, anthropometric, attitude to food consumption (TFEQ) and physical activity (GPAQ). RESULTS: the factorial structure of the TFEQ questionnaire in Spanish showed two factors: the "cognitive restriction" factor and the "disinhibition versus food" factor. With regard to nutritional status, it was found that 39.4% of the population had malnutrition due to excess. In relation to physical activity, half of the subjects performed less than 36 minutes of exercise per day. Individuals with uninhibited behavior towards food presented less practice of total physical activity. Additionally, subjects with low BMI and with greater age were more likely to present a restrictive behavior towards food. CONCLUSION: in the TFEQ questionnaire, two factors were found that explain the variation of behavior in relation to food consumption, which were associated with BMI and with physical activity in the study population.

INTRODUCCIÓN: la obesidad se ha transformado en una enfermedad crónica cuya etiología puede basarse en un desequilibrio entre el aporte y el gasto energético del individuo. Por lo tanto, el comportamiento frente al consumo de alimentos y la actividad física juegan un papel importante como determinantes clave en el resultado del balance energético. MÉTODOS: en el presente estudio se analizó la conducta frente al consumo de alimentos y la actividad física y su asociación con el estado nutricional en una población general chilena. Fue un estudio de corte transversal en 629 personas, pertenecientes a la comunidad universitaria de la Universidad Andres Bello. Los sujetos contestaron encuestas en línea acerca de antecedentes sociodemográficos, antropométricos, actitud frente al consumo de alimentos (TFEQ) y actividad física (GPAQ). RESULTADOS: la estructura factorial del cuestionario TFEQ en español mostró dos factores: el factor de ­restricción cognitiva­ y el factor de ­desinhibición frente a los alimentos­. Con relación al estado nutricional, se encontró que un 39,4% de la población presentó malnutrición por exceso. En cuanto a la actividad física, la mitad de los sujetos realizaban menos de 36 minutos de ejercicio al día. Los individuos con una conducta desinhibida frente a los alimentos presentaron menor práctica de actividad física total. Adicionalmente, sujetos con índice de masa corporal (IMC) bajo y con mayor edad tuvieron mayor probabilidad de presentar una conducta restrictiva frente a los alimentos. CONCLUSIÓN: en el cuestionario TFEQ se encontraron dos factores que explican la variación de la conducta frente al consumo de alimentos, los cuales se asociaron con IMC y con actividad física en la población de estudio.

Noncaloric Sweeteners in Children: A Controversial Theme.

Noncaloric sweeteners (NCS) are food additives used to provide sweetness without adding calories. Their consumption has become more widespread around the world in all age groups, including children. The aim of this study is to show the state of the art about the intake of noncaloric sweeteners in children, as well as their benefits and consumption risk. Scientific searchers were used (PUBMED, Scopus, and Scielo) to analyze articles that included keywords (noncaloric sweeteners/saccharin/cyclamate/acesulfame potassium/aspartame/sucralose/stevia/children) in English, Spanish, and Portuguese. Authors conclude that it is imperative that health professionals judiciously and individually evaluate the overall benefits and risks of NCS use in consumers before recommending their use. Different subgroups of the population incorporate products containing NCS in their diet with different objectives, which should be considered when recommending a diet plan for the consumer. In childhood, in earlier age groups, this type of additives should be used as a dietary alternative when other forms of prevention in obesity are not sufficient.

Connexinopathies: a structural and functional glimpse.

Mutations in human connexin (Cx) genes have been related to diseases, which we termed connexinopathies. Such hereditary disorders include nonsyndromic or syndromic deafness (Cx26, Cx30), Charcot Marie Tooth disease (Cx32), occulodentodigital dysplasia and cardiopathies (Cx43), and cataracts (Cx46, Cx50). Despite the clinical phenotypes of connexinopathies have been well documented, their pathogenic molecular determinants remain elusive. The purpose of this work is to identify common/uncommon patterns in channels function among Cx mutations linked to human diseases. To this end, we compiled and discussed the effect of mutations associated to Cx26, Cx32, Cx43, and Cx50 over gap junction channels and hemichannels, highlighting the function of the structural channel domains in which mutations are located and their possible role affecting oligomerization, gating and perm/selectivity processes.

Cyclic mechanical stretch induces cardiomyocyte orientation and polarization of the gap junction protein connexin43.

RATIONALE: Cyclic mechanical stretch (CMS) is an important physiological and pathological factor in the heart. OBJECTIVE: We examined whether CMS can affect localization of gap junctions with regard to the cell axis. METHODS AND RESULTS: Neonatal rat cardiomyocytes were cultured (7 days) on flexible 6-well plates. Thereafter, cells were kept static or stimulated with CMS (1 Hz; 0, 10, 20% elongation) for 0, 24, or 48 hours (with or without 10 micromol/L PD98059, 5 micromol/L BIM I (bisindolylmaleimide I), 2 micromol/L H8 [N-(2-methlyamino-ethyl)-5-isoquinoline-sulfonamid], or 0.1 micromol/L angiotensin II. Additionally, cells were exposed to 24 hours of CMS followed by 24 hours of static recovery. CMS (24 hour, 10%) induced elongation of the cardiomyocytes and orientation 79+/-8 degrees toward the stretch direction. Moreover, the distribution of connexin (Cx)43 together with N-cadherin changed, so that both proteins were accentuated at the cell poles, whereas in nonstretched cells, they were distributed around the cell without preferential localization. Additional angiotensin II reduced polar Cx43 accentuation. The CMS-induced changes in Cx43 were reversible within 24 hours after end of stretch, and could be completely prevented by the MEK1/2 inhibitor PD98059 but not by BIM I or H8. Moreover, stretch resulted in Cx43 protein and Cx43-mRNA upregulation and in a significant upregulation of the phosphorylated forms of ERK1/2, glycogen synthase kinase 3beta and AKT. Furthermore, CMS resulted in a significant increase of the transcription factors activator protein 1 and CREB (cAMP response element-binding protein) in the nucleus. CONCLUSIONS: CMS results in self-organization of cardiomyocytes leading to elongated cells orientated transverse to the stretch axis, enhanced Cx43 expression and Cx43 accentuation at the cell poles. The Cx43-changes seem to depend on the ERK1/2 signaling cascade.

Neonatal rat cardiomyocytes show characteristics of nonhomotypic gap junction channels.

Neonatal rat cardiomyocytes mainly coexpress the connexins Cx40, Cx43, and to a small amount Cx45, leading to potential formation of mixed (heteromeric/heterotypic) gap junction channels. Using the dual-voltage clamp technique with switching clamp circuits, the authors investigated voltage sensitivity of gap junction channels between cell pairs of Cx40, Cx43, and Cx45 stably transfected HeLa cells and compared those data to data obtained from cell pairs of cultured neonatal rat cardiomyocytes. In accordance to previously published data, the relationship between normalized conductance and transjunctional voltage (g/V(j)) was quasisymmetrical for the transfected HeLa cells, indicating homotypic gap junction channels. Boltzmann curves fitted to data obtained from neonatal rat cardiomyocyte pairs expressing both Cx40 and Cx43 showed an asymmetrical inactivation pattern, which cannot be explained by the presence of pure populations of homotypic gap junction channels of either isoform. In conclusion the authors assume the additional presence of heterotypic and possibly even heteromeric gap junction channels in neonatal rat cardiomyocytes.

Signal transduction and transcriptional control of cardiac connexin43 up-regulation after alpha 1-adrenoceptor stimulation.

Syncytial behavior of cardiac tissue is mainly controlled by the expression of cardiac gap junction proteins, and of these, connexin43 (Cx43) represents the predominant connexin in the working myocardium. Because the alpha(1)-adrenoceptor is involved in many cardiac diseases, the following experiments were performed to clarify the pathway whereby alpha(1)-adrenoceptor stimulation may control Cx43 expression. Cultured neonatal rat cardiomyocytes were stimulated with phenylephrine for 24 h, and Cx43 expression was investigated. Moreover, we investigated activation of p38 mitogenic-activated protein kinase (MAPK), p42/44-MAPK, and c-JUN NH(2)-terminal kinase (JNK) by phosphospecific enzyme-linked immunosorbent assay and nuclear translocation of the transcription factors c-fos and activator protein 1 (AP1). For verification of our results, a Cx43-promoter-enhanced green fluorescent protein (EGFP) construct using the complete promoter [2771 base pairs (bp)] or fragments (0-2421 bp) with EGFP under control of the Cx43 promoter was transfected into cardiomyocytes, and fluorescence intensity was investigated. Phenylephrine exposure caused approximately 2-fold up-regulation of Cx43 protein with an EC(50) of approximately 5 nM, which was significantly inhibited by bisindolylmaleimide I [protein kinase C (PKC) inhibitor], 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole (SB203580; p38 inhibitor), or 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059; p42/44 inhibitor). Similar findings were obtained for Cx43 mRNA. Furthermore, Cx43 up-regulation was accompanied by phosphorylation of p38, p42/44, and JNK. Moreover, we found translocation of c-fos and AP1 to the nucleus. Phenylephrine stimulation of Cx43-promoter EGFP-transfected cardiomyocytes significantly increased fluorescence, depending on the length of promoter fragments. A 91-bp fragment containing the first AP1 binding site produced approximately 50% of the fluorescence intensity of the complete promoter. Therefore, we conclude that alpha(1)-adrenoceptor stimulation up-regulates cardiac Cx43 expression via a PKC p38- and p42/44 MAPK-regulated pathway, possibly involving AP1.

Alpha-1-adrenoceptor subtype selective regulation of connexin 43 expression in rat cardiomyocytes.

Connexin43 (Cx43) is the predominant intercellular gap junction protein in the heart providing intercellular communication for the cell-to-cell transfer of electrical activation. In a previous study, we could show that alpha-adrenoceptor stimulation can affect Cx43 expression and function. We now wanted to elucidate which alpha1-adrenoceptor subtype might be involved. Cultured neonatal rat cardiomyocytes were exposed to various concentrations of phenylephrine (0.1-1,000 nM) for 24 h (n=6). Thereafter, cells were harvested, and after lysis, Cx43 content was determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot. Results were normalised to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Finally, we determined the effect of this treatment on intercellular gap junction conductivity using dual whole-cell voltage clamp. Similarly, we tested the effect of an additional treatment with either 10 nM prazosin or, to assess the subtypes, 10 nM of the alpha(1A)-antagonist RS17053 (n=6), 500 nM of the alpha(1B)-antagonist AH1111OA (n=6), or 50 nM of the alpha(1D)-antagonist BMY7378 (n = 6). Moreover, we incubated the cells for 24 h with the alpha(1A)-adrenoceptor agonist A61603 (10 nM). Phenylephrine led to enhanced Cx43 expression with a pEC50 8.00+/-0.06. The other cardiac connexins, Cx40 and Cx45, as well as GAPDH were not affected. This increase in Cx43 expression resulted in enhanced gap-junction conductance (44+/-4 nS vs 26+/-4 nS). As expected, the increased Cx43 expression could be antagonized by prazosin. Moreover, it was nearly completely inhibited by BMY7378 but was not significantly affected by RS17053. AH1111OA led to a moderate but incomplete inhibition. In contrast, beta-actin expression was also up-regulated by phenylephrine but was inhibited by prazosin or RS17053, while it was not affected by BMY7378 or AH1111OA. About 24 h exposure to the alpha(1A)-adrenoceptor agonist A61603 led to a twofold increase in beta-actin but did not affect Cx43. The low pEC50 value of about 1 nM for noradrenaline reported in our earlier study fits well to the hypothesis of an effect mediated predominantly via alpha(1D)-adrenoceptors, which is further supported by the finding of a nearly complete antagonisation of the phenylephrine effect by BMY7378. Thus, we conclude that cardiac Cx43 expression seems to be regulated via alpha(1)-adrenoceptors predominantly by subtype alpha(1D)-adrenoceptors, while other proteins like beta-actin seem to be regulated via alpha(1A)-adrenoceptors.