Changes of pulmonary beta-adrenergic receptors and their relationship with membranous phospholipid metabolism in endotoxin-induced lung injury in rats

The changes of beta-adrenergic receptors (AARs) in lung tissue in endotoxin-induced acute lung injury was investigated with radioligand bindig assay in rats. The lipid fluidity and phospholipid content of the cellular membrane of lung tissue were measured with fluorescent polarization and high performance liquid chromatography respectively. The findings were as follows:1- Four hours after endotoxin injection, there was a 47% decrease of the maximal binding capacity of fyARsas compared with the control.2. Endotoxin was able to decrease the lipid fluidity and phospholipid content of the pulmonary cellular membrane markedly and at the same time. There was an elevated activity of phospholipase A2 in the pulmonary tissueThese findings suggest that the decrease of the binding capacity of &ARs results in a decrease of the PAR mediated functions, which plays a ro1e in the pathogensis of endotoxin-induced acute lung injury and the activation of phospholipase A2 which is an important factor to reduce the phospholipid content of cell membrane and subsequently to decrease its lipid fluidity, can result in a reduction of the lateral diffusion and rotatory movement of β-ARs and to decrease the chances of β-ARs to bind with the ligands.

The role of α- and β-adrenergic receptors in the spasmolytic effects on rat ileum of Petroselinum crispum Latifolum(parsley)

Objective:To investigate Petroselinum crispum Latifolum(parsley) for treating stomach and intestinal disorders in Iran.Methods:An 80%ethanol extract was prepared from parsley seeds, and its antispasmodic activity assessed by measuring contractions of isolated ilea induced by 60 mM potassium chloride(KG).A piece of ileum from an adult male Wistar rat was dissected and mounted in an organ bath containing Tyrode’s solution,and ileum contractions were recorded by an isotonic transducer under one gram resting tension.The effect of parsley extract was measured in the presence of two antagonists’ of a - and(5-adrenoceptors.Results:These experiments showed that parsley extract inhibited the response to 60 mM KC1 in a concentration-dependent manner(P【0.01,n=7).The spasmolytic effect of parsley extract was unaffected by 1μM phentolamine or 1μM propranolol.Conclusions:This study shows that parsley seed extract is a relaxant of isolated rat ileum and the relaxation effect of extract does not involved adrenergic receptors.

B2 adrenergic receptors and morphological changes of the enteric nervous system in colorectal adenocarcinoma

To study the morphology of the enteric nervous system and the expression of beta-2 adrenergic (B2A) receptors in primary colorectal cancer.METHODSIn this study, we included forty-eight patients with primary colorectal cancer and nine patients for control tissue from the excision of a colonic segment for benign conditions. We determined the clinicopathological features and evaluated the immunohistochemical expression pattern of B2A receptors as well as the morphological changes of the enteric nervous system (ENS). In order to assess statistical differences, we used the student t-test for comparing the means of two groups and one-way analysis of variance with Bonferroni’s post hoc analysis for comparing the means of more than two groups. Correlations were assessed using the Pearson’s correlation coefficient.RESULTSB2A receptors were significantly associated with tumor grading, tumor size, tumor invasion, lymph node metastasis (P < 0.05), while there were no statistically significant associations with gender, CRC location and gross appearance (P > 0.05). We observed, on one hand, a decrease of the relative area for both Auerbach and Meissner plexuses with the increase of the tumor grading, and on the other hand, an increase of the relative area of other nervous elements not in the Meissner plexus or in the Auerbach plexus with the tumor grading. For G1 tumors we found that epithelial B2A area showed an inverse correlation with the Auerbach plexus areas [r(14) = -0.531, P < 0.05], while for G2 tumors, epithelial B2A areas showed an indirect variation with both the Auerbach plexus areas [r(14) = -0.453, P < 0.05] and the Meissner areas [r(14) = -0.825, P < 0.01]. For G3 tumors, the inverse dependence increased for both Auerbach [r(14) = -0.587, P < 0.05] and Meissner [r(14) = -0.934, P < 0.05] plexuses.CONCLUSIONB2A receptors play an important role in colorectal carcinogenesis and can be utilized as prognostic factors. Furthermore, study of the ENS in colorectal cancer may lead to targeted molecular therapies.

Clinical value of detecting autoantibodies against β1-, β2-, and α1-adrenergic receptors in carvedilol treatment of patients with heart failure

Objective To determine the possible association of anti-β1-adrenergic receptors(anti-β1-AR), anti-β2-AR and anti-α1-AR with carvedilol treatment in patients with heart failure(HF). Methods A total of 267 HF patients were prospectively enrolled. Blood samples were measured by an enzyme-linked immunosorbent assay. All of the patients received carvedilol for their HF. Each patient was followed up for six months and their cardiac function was measured. Results The final analysis encompassed 137 patients comprising 65 patients with three autoantibodies(positive group) and 72 patients without all three autoantibodies but with one or two autoantibodies(negative group). The frequency and geometric mean titer of anti-β1-AR, anti-β2-AR, and anti-α1-AR were significantly lower in the group without all three autoantibodies after six months of carvedilol treatment(all P < 0.01;from 100% to 57%, 50%, and 49%, respectively;and from 1: 118, 1: 138, and 1: 130 to 1: 72, 1: 61, and 1: 67, respectively). Furthermore, 28 patients in the positive group demonstrated complete ablation of autoantibodies. In addition, left ventricular remodelling and function was significantly improved by the use of carvedilol combined with the standard treatment regime for six months in the positive group(P < 0.01) when compared to the negative group(P < 0.05). Conclusions Carvedilol treatment significantly decreases frequency and geometric mean titer in patients with all three autoantibodies, even up to complete ablation, and significantly improved cardiac function and remodelling. The effect of carvedilol is probably correlated to the presence of all three autoantibodies.

Association between essential hypertension and polymorphisms of beta 1 adrenergic receptor gene G1165C (Gly389Arg) in Chinese Mongolian population

BACKGROUND： The prevalences of hypertension, cerebrovascular diseases, etc. are higher in Mongolian population because of the influence of various factors including genetics, geography, diet, etc. Therefore, it is helpful to develop researches on the genetics of various diseases including hypertension in Mongolian population. OBJECTIVE： To analyze the association between the polymorphism of beta1 adrenergic receptor （β1-AR） gene G1165C （Arg389Gly）, an important candidate gene for various diseases of cardiovascular system, and essential hypertension in Mongolian population. DESIGN ： A cross-sectional study SETTINGS： Department of Neurology, the First Affiliated Hospital of Inner Mongolia Medical College; Wulate Houqi Red Cross Society. PARTICIPANTS： The survey was carried out from February 2003 to March 2005. Totally 239 Mongolian residents, whose blood relations of 3 generations were all Mongolians, were selected from Wulate Houqi, Inner Mongolia, and they were all informed with the survey and detected items. Based on the diagnostic standard of hypertension set by WHO in 1999, the subjects were divided into two groups according to the level blood pressure： ① Normal blood pressure group （n=117）： systolic blood pressure （SBP） 〈 140 mm Hg （1 mm Hg =0.133 kPa）, diastolic blood pressure （DBP） 〈 90 mm Hg, and those having histories of cerebrovascular disease, heart disease, diseases of liver, kidney and tiroides, and diabetes mellitus were excluded. ② Essential hypertension group （n=122）： including 51 patients with simple high SBP. All the enrolled subjects had no blood relationship with each other, and had no history of miscegenation. METHODS ： The body height, body mass, waist circumference and blood lipids were measured routinely, and their habits of smoking and drinking were also investigated. Penpheral venous blood （5 mL） was drawn, the genome DNA was extracted, and the polymorphisms of the β1-AR Gl165C （Gly389Arg） genotype were detected with the Sequenom system. Polymerase chain reaction （PCR） experiment and SNP detection were performed in Huada Gene Laboratory of Bejing, then the univariate analysis of variance was applied in the sample comparison among groups, and the chi-square test was used to compare the genotypes and allele frequencies. The odd ratio （OR） and 95% confidence interval （CO were calculated. MAIN OUTCOME MEASURES： The distributions of β1-AR Gl165C （Gly389Arg） genotypes and alleles were observed. RESULTS： A11 the 239 subjects were involved in the analysis of results, and no one missed, ①Comparison of β1-AR G1165C （Gly389Arg） genotypes and allele distnbutions： In Mongolian population, the frequencies of CC and GG＋GC genotypes at β1-AR G1165C （Gly389Arg） site in the essential hypertension group （72%, 28%） were not significantly different from those in the normal blood pressure group （67%, 33%） （xz=0.841, P=-0.359; OR 0.773, 95%Cl： 0.445-1.342）; The frequencies of C and G alleles also had no significant differences between the essential hypertension group （85%, 15%） and the normal blood pressure group （82%, 18%） （x^2=1.136, P=-0.287; OR： 0.769, 95%Cl： 0.747-1.248）. ②The frequencies of CC and GG＋GC genotypes at β1-AR G1165C （Gly389Arg） site had no significant differences between the patients with simple high SBP （71%, 29%） and the normal blood pressure group （x^2=0.250, P=-0.617; OR： 0.833, 95%C/： 0.408-1.703）; The frequencies of C and G alleles were not significantly different between the patients with simple high SBP （86%, 14%） and the normal blood pressure group （x^2=0.670, P=-0.413; OR 0.766, 95%Cl： 0.404-1.453）. CONCLUSION： In Mongolian population, the distributions of the genotypes and alleles of β1-AR Gl165C （Gly389Arg） have no obvious differences between the subjects with normal blood pressure and the patients with essential hypertension （including simple SBP increase）, which suggests that G1165C （Glu389Asp） site of β1-AR gene may be not a genetic mark of essential hypertension and simple high SBP in Mongolian population.

β_(2) and α_(2) adrenergic receptors mediate the proneurogenic in vitro effects of norquetiapine

Positive modulation of adult hippocampal neurogenesis may contribute to the therapeutic effects of clinically relevant antidepressant drugs,including atypical antipsychotics.Quetiapine,an antipsychotic which represents a therapeutic option in patients who are resistant to classical antidepressants,promotes adult hippocampal neurogenesis in preclinical studies.Norquetiapine,the key active metabolite of quetiapine in humans,has a distinctive receptor profile than the parent compound.The drug is indeed a high affinity norepinephrine transporter inhibitor and such activity has been proposed to contribute to its antidepressant effect.At present,no information is available on the effects of norquetiapine on adult neurogenesis.We extensively investigated the activity of quetiapine and norquetiapine on adult murine neural stem/progenitor cells and their progeny.Additionally,selective antagonists for β_(2)/α_(2) adrenergic receptors allowed us to evaluate if these receptors could mediate quetiapine and norquetiapine effects.We demonstrated that both drugs elicit in vitro proneurogenic effects but also that norquetiapine had distinctive properties which may depend on its ability to inhibit norepinephrine transporter and involve β_(2)/α_(2) adrenergic receptors.Animal care and experimental procedures were approved by the Institutional Animal Care and Use Committees(IACUC)at University of Piemonte Orientale,Italy(approval No.1033/2015PR)on September 29,2015.

Changes of pulmonary α_1-and β-adrenergic receptors after endotoxininduced acute lung injury in rats

Changes of pulmonary α1-and βadrenergic receptors (α1- ARs and β-ARs) after endotoxin-induced lung injury were dynamically observed with radioligand binding assay and the pulmonary rnicrovascular permeability and histopathology were also studied in rats to investigate the relationship between changes of pu1monary ARs and acute lung injury. It was found that the contents of both α1-ARs and β-ARs were significantly decreased after endotoxin-induced acute lung injury. On the basis of these findings, the authors inferred that the down regulation of β-ARs might be one of the factors to increase pulmonary microvascular permeability and that of α1-ARs seems to be a protective reaction. This inference might serve as the theoretical basis to treat pulmonary edema with α1-antagonists and β-agonists clinically.

Effect of Cardiopulmonary Bypass on Beta Adrenergic Receptor Adenylate Cyclase System on Surfaces of Peripheral Lymphocytes

Summary: The experimental results showed that the level of CAMP, the ratio of cAPM to cGMP, IL-2R expression and IL-2 production in vitro in lymphocytes immediate and 2 weeks after car- diopulmonary bypass (CPB) were significantly lower than those before anesthetics in the patients undergoing cardiac surgery with CPB. These findings suggested that CPB could cause serious damage to adrenergic beta receptor-adenylate cyclase system on circulating lymphocytes surfaces, which might be one of the mechanisms resulting in immunosuppression after open heart surgery with CPB.

Experimental study on alteration of adrenergic receptors activity in neuronal membranes protein of cerebral cortex following brain trau ma in rats

Objective:To definethecourseof changestakenbyα 1 andβadrenergicreceptors(AR)activityaftertraumatic braininjury(TBI)andexploretheapproachforsecondarybraininjury(SBI)management.Methods:Theneuronalmem-braneproteinof cortexwereextractedfromtheratssubjectto traumaticbraininjury,andthechangesofα 1 -andβ-ARac-tivitiesintheneuronalmembraneswereexaminedby radioligandbindingassay(RLBA).Results:α 1 -andβ-ARactivities underwentobviouschanges,reachingtheirpeakvaluesat24h afterTBI.α 1 -ARbindingdensity(B max )reducedby22.6%whiletheligandaffinityincreasedby66.7%,andforβ-AR,however,B max increasedby116.9%andtheligandaffinityre-ducedby50.7%.Theirantagonistscouldcounteractthechangesofα 1 -andβ-ARactivity.Con clu sion:Thepatternsof changesvariesbetweenα 1 -andβ-ARactivityafterTBI, suggestingtheirdifferentrolesintheneuronalmembranesafter braintrauma,andtimelyadministrationof ARantagonistsispotentiallybeneficialinTBImanagement.

Olfactory receptors in neural regeneration in the central nervous system

Olfactory receptors are crucial for detecting odors and play a vital role in our sense of smell,influencing behaviors from food choices to emotional memories.These receptors also contribute to our perception of flavor and have potential applications in medical diagnostics and environmental monitoring.The ability of the olfactory system to regenerate its sensory neurons provides a unique model to study neural regeneration,a phenomenon largely absent in the central nervous system.Insights gained from how olfactory neurons continuously replace themselves and reestablish functional connections can provide strategies to promote similar regenerative processes in the central nervous system,where damage often results in permanent deficits.Understanding the molecular and cellular mechanisms underpinning olfactory neuron regeneration could pave the way for developing therapeutic approaches to treat spinal co rd injuries and neurodegenerative diseases like Alzheimer's disease.Olfa ctory receptors are found in almost any cell of eve ry orga n/tissue of the mammalian body.This ectopic expression provides insights into the chemical structures that can activate olfactory receptors.In addition to odors,olfactory receptors in ectopic expression may respond to endogenous compounds and molecules produced by mucosal colonizing microbiota.The analysis of the function of olfactory receptors in ectopic expression provides valuable information on the signaling pathway engaged upon receptor activation and the receptor's role in proliferation and cell differentiation mechanisms.This review explo res the ectopic expression of olfa ctory receptors and the role they may play in neural regeneration within the central nervous system,with particular attention to compounds that can activate these receptors to initiate regenerative processes.Evidence suggests that olfactory receptors could serve as potential therapeutic targets for enhancing neural repair and recovery following central nervous system injuries.

Blocking beta 2-adrenergic receptor inhibits dendrite ramification in a mouse model of Alzheimer's disease

Dendrite ramification affects synaptic strength and plays a crucial role in memory. Previous studies revealed a correlation between beta 2-adrenergic receptor dysfunction and Alzheimer＇s disease （AD）, although the mechanism involved is still poorly understood. The current study investigated the potential effect of the selective β2-adrenergic receptor antagonist, ICI 118551 （ICI）, on Aβ deposits and AD-related cognitive impairment. Morris water maze test results demonstrated that the performance of AD-transgenic （TG） mice treated with ICI （AD-TG/ICI） was significantly poorer compared with NaCl-treated AD-TG mice （AD-TG/NaCl）, suggesting that β2-adrenergic receptor blockage by ICI might reduce the learning and memory abilities of mice. Golgi staining and immunohistochemical staining revealed that blockage of the β2-adrenergic receptor by ICI treatment decreased the number of dendritic branches, and ICI treatment in AD-TG mice decreased the expression of hippocampal synaptophysin and synapsin 1. Western blot assay results showed that the blockage of β2-adrener- gic receptor increased amyloid-β accumulation by downregulating hippocampal a-secretase activity and increasing the phosphorylation of amyloid precursor protein. These findings suggest that blocking the β2-adrenergic receptor inhibits dendrite ramification of hippocampal neurons in a mouse model of AD.

Inhibition of central sympathetic nervous tone improves cardiomyocyte contraction by increasing the response of beta 2-adrenergic receptor in aged rats

In the present study,selective β1-adrenergic receptor antagonist CGP20712A and selective β2-adrenergic receptor antagonist ICI 118551 were administered to isolated cardiomyocytes from young （4-6 months）,aged （18-20 months）,and clonidine-pretreated aged （18-20 months） Sprague-Dawley rats.Cardiomyocyte contraction amplitude was measured to assess cardiomyocyte response to the β-adrenergic receptor agonist,isoprenaline.CGP20712A reduced cardiomyocyte contraction amplitude in young and aged groups and significantly reduced contraction amplitude in cells from young rats.ICI 118551 had no effect on cardiomyocyte contraction amplitude in young rats,but significantly decreased contraction amplitude in the aged groups,in particular in the clonidine-pretreated aged rats.Results demonstrated that reduced central sympathetic tone improved cardiomyocyte contraction in aged rats by improving the response of β2-adrenergic receptor to isoprenaline.

Interactive Effects of Zinc and Zilpaterol Hydrochloride on Bovine <i>β</i>-Adrenergic Receptors

The objective of this study was to determine if the addition of zinc (Zn) in combination with zilpaterol HCL (ZH) affected the interaction of ZH with the beta2-adrenergic receptor (β-AR) by altering cAMP production, gene expression, and protein abundance in cultured skeletal muscle cells. Cultures of muscle bovine satellite cells were established and treated at 120 h with: 1) 0 μM Zn/zilpaterol hydrochloride (ZH;CON);2) 0 μM Zn/10 μM ZH (ZH);3) 1 μM Zn from Zn chloride/0 μM ZH (Zn);4) 1 μM Zn from Zn chloride/10 μM ZH (ZN/ZH) in differentiation media for an additional 0, 6, 24, 48 and 96 h. Protein and mRNA were isolated and quantified at 24 and 96 h, and cAMP was measured at 0, 6, 24, 48 and 96 h. At 0, 24, 48 and 96 h, no differences (P > 0.05) were detected in cAMP production. At 6 h, Zn cells had the greatest concentration of cAMP (P < 0.05) compared to ZH treatments. No differences (P > 0.05) were detected in mRNA abundance at 24 h. At 96 h, 0 μM Zn/10 μM ZH cells had an increased abundance of myosin heavy chain (MHC)-I mRNA (P < 0.05) compared to CON. Furthermore, ZH had a greater abundance of MHC-IIX mRNA (P < 0.05) and a tendency for a greater abundance of IGF-1 mRNA (P < 0.15) compared to CON and ZN/ZH. No differences (P > 0.05) were detected in the protein abundance of β1AR and the β2AR. These results indicated Zn and ZH in combination did not have an additive effect on β2-AR function as indicated by cAMP concentrations.

THE DISTRIBUTION OF BETA-ADRENERGIC RECEPTORS IN GUINEA PIG LUNGS AND THEIR CHANGES IN EXPERIMENTAL ALLERGIC ASTHMA

In this paper, the distribution of pulmonary beta-adrenergic receptors (beta-receptors) innormal and experimental allergic asthmatic guinea pigs was determined using autoradiograph-ic method. The results showed that the distribution of beta-receptors in the lung sections waswidespread. There was a significant decrease of beta-receptor density in several tissue struc-tures of asthmatic guinea pig lungs compared with the controls, a 23.73% decrease in beta-recep-tor binding sites in bronchiolar smooth muscles and a 18.65% decrease in bronchial smoothmuscles; a 23 .53%. a 14.23% and a 17. 16% decrease in bronchiolar epithelium, in bronchialepithelium and in alveolar epithelium respectively. The results indicated that the beta-recep-tor decrease in smooth muscles in experimental asthmatic guinea pig lungs might be one ofthe important factors which made the tension of smooth muscles increase. The relationshipbetween the beta-receptor decrease of other sites and bronchial asthma needs to be studiedfurther.

Correlation of beta－receptors in human pathological brain tissue and in peripheral blood lymphocytes

Beta-adrenergic receptors in the brain are involved in modulating cerebral blood flow (CBF) and cerebral energy metabolism (CEM). Because of the difficult availability of brain tissue samples, investigation of the relevant beta-receptor of brain is limited. In the present study, the density of beta-receptors in brain tissues and in circulating lymphocytes was measured by the method of radio-ligand receptor binding (RLBA), in brain injury or brain tumor and a correlation analysis was performed. Our results show that there is linear correlation between the beta-receptors in brain tissue and in peripheral blood lymphocytes (r= 0. 811 , P<0. 01) in cases of increased permeability of bloodbrain barrier during brain injury or brain tumor.

Beta-adrenergic receptor polymorphisms: A basis for pharmacogenetics

Aims: Polymorphisms of the β-adrenergic receptor, the frequency of which may differ in ethnic groups, alters β-receptor function. The aim of this study was to elucidate the frequency of β1 and β2-adrenergic receptor polymorphisms in healthy Greeks and to compare with those of Caucasian European (Euro) and African American (AA) origin. Methods: Ninety-nine individuals with a median age of 63 without clinical evidence of any disease were studied. Blood samples were obtained and common β1 and β2-adrenergic receptor polymorphisms that change the en-coded amino acid were determined by pyrosequencing. Results: The most common β1-adrenergic receptor polymorphism in Greeks is nucleotide substitution cytosine for guanine at position 1165 (1165 C/G) resulting in amino acid substitution arginine for glycine at position 389 (389 Arg/Gly) with a minor allele frequency of 28% (Euro 27%, AA 42%);this polymorphism increases the sensitivity of the β1-receptor. The most common β2-adrenergic receptor polymorphism in Greeks is the nucleotide substitution guanine for adenine at position 46 (46 G/A) resulting in amino acid substitution glycine for arginine at position 16 (16 Gly/Arg) with a minor allele frequency of 38% (Euro 41%, AA 50%);this polymerphism facilitates receptor down-regulation during chronic adrenergic stimulation. Conclusion: The most common β1 and β2-adrenergic receptor polymorphisms in the Greek population are similar to those of other European ancestry, and less common than in those of African origin indicating variability in ethnic groups. This information provides insight into common polymorphisms that may assist in optimizing β-antagonist and agonist therapy.

Role of β-Adrenergic Signal Transduction Pathway on Myocardial Ischemic Preconditioning of Rats

To study the changes in every part of the β-adrenergic signal transduction pathway and their effects on ischemic preconditioning of rat myocardium in vivo. SD rats were divided into three groups： IP group, I/R group and CON group. The IP group was further divided into PC1-, 2-, 3-, and PC1＋, 2＋, 3＋ groups according to preconditioning procedure. The rats received surgical procedure and underwent left coronary artery occlusion and reperfusion. We analyzed the infarct size by TTC staining, measured serum myocardial enzymes, studied the β-AR Bmax and Kd by radioligand binding assay of receptors, checked the activity of AC and PKA by the method of biochemistry and examined the content of cAMP by radioimmunoassay. The infarct area was much smaller in the IP group than in the I/R group （P〈0. 001）, while the enzymes were significantly higher in I/R （P〈0. 001）. The Bmax of β-AR in IP was much higher than that in I/R （P〈0. 001）, but no difference in Kd could be seen between IP and I/R groups. In IP, the activity of AC and PKA and the content of cAMP were higher than those in I/R （P〈0.05, 0. 002 and 0. 001, respectively）. In the procedure of preconditioning, the content of cAMP and the activity of PKA showed the characteristic of cyclic fluctuation. Ischemic preconditioning can protect the heart from necrosis and reduce endo-enzyme leakage. The system of β-adrenergic signal transduction pathway probably takes part in the protection effect of the IP, which might be elicited by the PKA .

The beta-adrenergic blocker carvedilol restores L-type calcium current in a myocardial infarction model of rabbit

Background Carvedilol, an antagonist of α1- and β-adrenergic receptors, has shown efficacy in reducing all-cause death and arrhythmia death for ischemic heart disease and congestive heart failure in several large-scale trials. It has been found to prevent ventricular remodeling, and recently was reported to reverse down-regulation of Na^+ channel in a chronic heart failure model. This study was conducted to investigate whether carvedilol could reverse the ion remodeling in a myocardial infarction model of rabbit.Methods After the procedure of coronary ligation, animals were randomized to placebo or carvedilol treatment (5 mg/kg). Action potentials, L-type calcium current (I_(ca L)) and the effect of isoproterenol stimulation on I_(ca L) were measured using whole-cell patch method. Evaluation of the expression of calcium channel subunits was carried out by RT-PCR and Western blot. Results The results indicate that mean peak I_(ca L) densities (pA/pF) at +10 mV was reduced in postinfarction myocytes (5.33±0.45, n=25) compared to sham myocytes (6.52±0.21, n=20). Treatment of myocardial infarction rabbits with carvedilol could restore it partially (5.91±0.39, n=20, P<0.05). However, steady-state activation parameters were similar in three groups. With stimulation by isoproterenol (1 μmol/L) I_(ca L) increased in all three groups, but the increase was smaller in postinfarction myocytes. mRNA levels of calcium channel subunit CaA1 gene was decreased but CaB2a, CaB2b and CaB3 mRNA levels did not change after MI. Corresponding change in CaA1 protein was also observed. Conclusions The results demonstrate that carvedilol restores I_(ca L) density and reverse the downregulation of CaA1 postinfarction.

Effects ofβ_2-Adrenergic Antagonist on Cytosolic Ca^(2+) in Ventricular Myocytes from Infarcted Rat Heart

Objectives To investigate the effects of β2-adrenergic antagonist on cytosolic Ca^2 ＋ （[Ca^2＋ ]i） in ventricular myocytes from infarcted rat heart. Methods A ligature was placed around left anterior descending coronary artery of rat hearts. Rats in the control group were sham-operated. Cardiomyocytes were dissociated at two, four, eight weeks after myocardial infarction （MI） and [Ca^2＋]i was measured via fura-2 fluorescence. The response of cardiomyocytes to isoproterenol in presence or absence of betal-adrenergic antagonist atenolol, beta2-adrenergic antagonist ICI118, 551 or non-selective β1, 2- adrenergic antagonists propranolol was examined. Results The followings were found that ICI 118, 551 had no significant effects on the rise of [Ca^2＋]i induced by isoproterenol in normal ventricular myocytes （P 〉 0.05）, ICI118, 551 only significantly attenuated the rise of [Ca^2＋]i induced by isoproterenol at four weeks and eight weeks after MI （24.5%±5.7% vs 57.8% ± 13.2%, P〈 0.01; 12.2%±7.9% vs 44.6%±11.3%, P〈 0.01）. Atenolol had suppressive effects only in the control group and the post-MI group of two weeks （P 〈 0.05）, and propranolol had suppressive effects in the control and all the three post-MI groups （P 〈 0.01）. Conclusions Beta2-adrenergic antagonist ICI118, 551 may exert negative effects on Ca^2＋ overload initiated by sympathetic stimulation after MI.

Gene transfer of a β_2-adrenergic receptor kinase inhibitor up-regulates the level of β_2-adrenergic receptor and cAMP in the asthmatic murine lung

Objective： To investigate the effects of gene transfer of a β-adrenergic receptor（β-AR） kinase inhibitor（β ARIct） on pulmonary β2-adrenergic receptor and cAMP following β2-AR agonist treatment in asthmatic mice, and to analyze the relationship between the routes of gene delivery and the changes of β2AR and cAMP. Methods： BALB/c mice were sensitized and challenged by ovalbumin to establish the asthmatic model treated with βAR agonist （salbutamol injected intramuscularly）. The plasmid with the expression of βARKct was constructed and βARKct gene transfer was performed through intravenous injection or intratracheal instillation in asthmatic mice. The gene expression was measured with Western blot analysis, and the changes of pulmonary β-AR and cAMP evaluated by Radioimmunoassay. Results： The expression of tranfered βARKct gene was detectable in lungs and it was expressed more in the lungs of the mice receiving intratracheally plasmid than those receiving intravenously. The levels of βAR and cAMP were upregulated after using plasmid-βARKct to the asthmatic mice treated with βAR agonist. Conclusion： Our results indicated that there were down-regulation of βAR and cAMP in asthmatic mice treated with βAR agonist. Gene transfer of βARKct could inhibit the extent of the down-regulation of βAR and cAMP. The route of gene delivery could also affect the degree of up-regulation of βAR and cAMP. Gene transfer βARKct may provide a novel approach to the therapeutic strategy for asthma.