TGF-β1与缺血再灌注心肌细胞凋亡的关系

取新生SD大鼠心肌细胞,随机分为四组：①正常对照组（A组）：在不含处理因素的含10%胎牛血清DMEM培养基中置37℃、5%CO2、95%空气培养箱培养48h;②缺血再灌注诱导凋亡模型组（B组）：在不含血清的低糖DMEM培养基,三气培养箱中培养48h后,置10%胎牛血清DMEM培养基,37℃、5%CO2、95%空气培养箱中培养3h;③转化生长因子（TGF）-β1干预组（C组）：在不含血清的低糖DMEM培养基加入TGF-β1（5ng/ml）,先于三气培养箱中培养48h后,置10%胎牛血清、TGF-β1（5ng/ml）DMEM培养基,37℃、5%CO2、95%空气培养箱中培养3h;④TGF-β1抑制剂干预组（D组）：培养基中加入TGF-β1同时加入其抑制剂LY364947（59nmol/L）,余同C组。采用流式细胞术及Tunel染色法检测各组细胞凋亡率。结果A、B、C、D组心肌细胞凋亡率分别为5.89%±1.28%、26.68%±6.17%、54.19%±11.86%、31.31%±3.78%;C组与其他各组之间比较,P均〈0.05,D组与B组比较,P〉0.05。认为TGF-β1可以诱导心肌细胞缺血再灌注损伤后心肌细胞凋亡,而LY364947可抑制TGF-β1的作用。     

肾上腺素能β受体在去甲肾上腺素引起的心肌细胞离子泵损害中的作用研究

本文报告以去甲肾上腺素(NE)50μg/kg由家兔耳静脉注射,2分钟后致死。取左心室肌制备膜微粒体,测Na~+/K~+-ATP酶及Ca~(2+)-ATP酶活性,过氧化脂质(LPO)含量;取心尖部肌肉匀浆后提取及测定cAMP含量。结果,NE明显抑制二酶活性,P均<0.001,明显增加LPO及cAMP含量,P均<0.001。在注射NE前2分钟自耳静脉注射α受体阻滞剂酚妥拉明1mg/kg,或β受体阻滞剂心得静60μg/kg,或二者合用。结果示β受体阻滞剂明显阻抑NE效应,P<0.001或0.05;而α受体阻滞剂未显示阻抑作用,P均>0.05。结果提示,β受体在介导NE效应中占优势。     

抗β1-肾上腺素受体抗体对大鼠T淋巴细胞的作用

目的观察抗β1-肾上腺素受体（AR）抗体对大鼠T淋巴细胞的作用。方法用人工合成的β1-肾上腺素受体细胞外第二环肽段（β1-AR—ECⅡ）作为抗原主动免疫大鼠,采用流式细胞技术测定大鼠外周血T淋巴细胞亚群的变化;观察抗β1-AR自身抗体对培养的淋巴结T细胞的影响。结果免疫组血清中T淋巴细胞亚群CD4^＋／CD8^＋在处理24h后开始升高,在第7天时达到高峰并持续2个月;抗β1-AR自身抗体可促进T淋巴细胞增殖,与β1-AR特异性阻断剂Metoprolol或β1-AR—ECⅡ共同作用时,可使抗体的促增殖效能显著减弱。结论抗β1-AR自身抗体可以使免疫系统失衡,促进T淋巴细胞的增殖。     

肺癌抑癌基因1对HepG2细胞生长的抑制效应

目的探讨肺癌抑癌基因1（TSLC1）对人肝癌细胞株HepG2生长的影响。方法RT-PCR法制备TSLC1全长cDNA并克隆至真核表达载体pCI-neo，稳定转染至肝癌细胞系HepG2中。以转染空质粒pCI-neo的HepG2细胞为对照组，野生型HepG2细胞为空白组，显微镜下观察细胞形态，MTT法检测细胞增殖，FACSort流式细胞仪检测细胞周期，AnnexinV／PI双染法检测细胞凋亡情况。结果实验建立了高表达TSLCI蛋白的稳定细胞株。实验组细胞呈多角形，聚集成团，细胞之间的黏附非常紧密，对照组和空白组细胞呈梭形，细胞与细胞之间较疏散。与对照组和空白组相比，实验组细胞株细胞生长速度减慢，增殖受到明显抑制，G0／G1期细胞为63．66%±3．83％，高于对照组（47．45％±0．91％）和空白组（54．47％±0．96％）；S期细胞数为22．90％±6．04％，低于对照组（36．58％±0．61％）和空白组（33．61％±2．99％），P〈0．01，实验组细胞周期发生了G0/G1期阻滞。实验组细胞早期凋亡率和晚期凋亡率分别为17．09%±0．20％和16．11％±0．40％，与对照组和空白组细胞相比均明显升高（P〈0．01）。结论TSLC1基因明显抑制HepG2细胞生长，并诱导细胞发生凋亡。     

氯通道在顺铂诱导的鼻咽癌细胞凋亡性容积减小中的作用

目的探讨氯通道在凋亡诱导剂诱导的鼻咽癌凋亡性细胞容积减小中的作用以及对凋亡的影响。方法用顺铂（cDDP）诱导建立CNE-2Z细胞凋亡模型,用流式细胞仪检测细胞凋亡,采用Scion Image图像分析软件控制定时拍摄固定视野活细胞图像,检测细胞容积变化。结果①cDDP诱导的细胞凋亡早期即可观察到细胞容积的减小。在连续观察的6 h中,细胞体积持续减小,6 h末细胞容积减少14.2%±2.6%。②氯通道阻断剂NPPB（100μmol/L）明显抑制cDDP诱导的凋亡性容积减小,抑制率为98.6%±1.8%。③cDDP作用CNE-2Z细胞48 h后,诱导的细胞凋亡率为23.1%±2.5%,而在NPPB的保护作用下,凋亡率下降到3.8%±0.5%,抑制率为83.5%±10.4%。结论氯通道激活引起的细胞容积减小是介导细胞凋亡的机制之一。     

β_2-肾上腺素受体亚型激动对于血管平滑肌细胞增殖的影响

目的研究β2-肾上腺素受体亚型(beta2-adrenergic receptor,β2-AR)激动对于血管平滑肌细胞(VSMC)增殖的调控效应。方法应用携带重组β2-AR片段的腺病毒感染VSMC制备受体过表达模型。分别应用Zinterol(ZIN)以及异丙基肾上腺素(ISO)刺激生理状态和β2-AR过表达的平滑肌细胞后,采用四甲基偶氮唑盐(MTT)比色法和细胞计数法检测吸光度(A,曾称光密度OD)值和细胞数目的改变。结果ZIN刺激1天时A值开始下降(P<0.05),3天时抑制作用达高峰,抑制率为(32.00±1.62)%。细胞计数法测得ZIN激动3天时细胞数为对照组的(69.29±9.26)%。应用CGP20712A阻断β1-AR激活后,非选择性-βAR激动剂ISO刺激细胞后得到结果相似。特异性β2-AR拮抗剂ICI 118,551可逆转此抑制效应。ISO刺激过表达的β2-AR 3天时MTT检测结果相似。结论β2-AR亚型激动可抑制VSMC的增殖。     

麝香保心丸对心力衰竭大鼠肾脏α_1及β肾上腺素受体各亚型表达的影响

目的：探讨麝香保心丸对心力衰竭大鼠肾脏α1-肾上腺素受体（α1-adrenergic receptorα1-AR）和β-肾上腺素受体（β-adrenergic receptorβ-AR）各亚型表达水平的影响。方法：选择雄性Wistar大鼠80只,随机分为正常对照组（10只）、假手术组（10只）,其余60只制作心肌梗死后心力衰竭模型,模型成功35只并将其随机分为心力衰竭组（9只）、阳性药物对照组（8只）、麝香保心丸低剂量组（9只）和麝香保心丸高剂量组（9只）。取大鼠肾脏皮质,采用Western Blot分别测定各组大鼠α1-AR和β-AR各亚型蛋白表达水平。结果：假手术组与正常对照组α1A-AR和β1-AR表达水平比较,差异无统计学意义（P〉0.05）;与假手术组比较,心力衰竭组大鼠α1A-AR、β1-AR表达水平明显下调,差异有统计学意义（P〈0.05）;与心力衰竭组比较,阳性药物对照组、低剂量组、高剂量组大鼠α1A-AR、β1-AR表达水平明显上调,差异有统计学意义（P〈0.05）;与低剂量组比较,阳性药物对照组、高剂量组大鼠α1A-AR表达上调更为显著（P〈0.05）。各组大鼠α1B-AR、α1D-AR和β2-AR表达水平比较,差异无统计学意义（P〉0.05）。结论：麝香保心丸缓解了心力衰竭大鼠肾脏α1-AR和β-AR各亚型表达水平的下调,对恢复肾脏功能、改善心力衰竭起到了有益的作用。同时,与小剂量麝香保心丸相比,高剂量疗效更为显著。     

去甲肾上腺素对大鼠肝星状细胞作用的实验研究

目的 探讨交感神经系统在肝纤维化发生和发展中的作用. 方法采用免疫荧光和RT-PCR检测体外培养的肝星状细胞(HSC)中α1、β2-肾上腺素能受体的表达;用四甲基偶氮唑盐法检测不同浓度的去甲肾上腺素(NE)对HSC增殖活性的影响.同时用RT-PCR检测受NE作用后HSC的活化指标胶原蛋白-1、转化生长因子β(TGF β)及α-平滑肌动蛋白(α-SMA)的表达.用高效液相色谱-电化学法测定活化的HSC中交感神经递质NE的水平. 结果α1和β2-肾上腺素能受体表达于HSC的胞膜和胞质内;NE可呈剂量依赖性地促进HSC增殖,在浓度为100μmol/L时达到最大效应,F=140.464,P<0.05,差异有统计学意义.以NE 100 μmol/L作用细胞24h后,可显著促进反应HSC活化的指标上升,胶原蛋白-1表达为0.3022±0.0610,TGF β表达为2.2080±0.2151,α-SMA mRNA表达为0.5469±0.0108,与对照组胶原蛋白-1(0.1040±0.0556)、TGF β(1.1190±0.0070)、α-SMA mRNA表达(0.0759±0.0449)比较,t值分别为-4.160、-8.763和-17.651,P值均<0.05,差异均有统计学意义.HSC可以合成并释放NE,且受血小板衍生生长因子(10ng/ml)刺激后HSC中NE含量为(14.24±0.21)ng/ml,对照组为(11.34±0.15)ng/ml,两组比较,t=-32.907,P<0.05,差异有统计意义.结论 抑制交感神经系统使HSC活性降低对临床上治疗肝纤维化有一定的指导意义.     

D_3多巴胺受体对α肾上腺素能受体介导的促动脉平滑肌细胞增殖作用的影响

目的观察D3多巴胺受体对肾上腺素α受体介导的血管平滑肌细胞(VSMC)增殖的影响。方法用去甲肾上腺素(NE)刺激SD大鼠的VSMC,观察在D3受体激动剂(PD128907)存在的情况下,NE促增殖作用的变化,其中细胞增殖用3H-TdR掺入量表示。结果NE通过肾上腺素α受体促进SD大鼠VSMC增殖,该作用呈现浓度依赖性关系。PD128907低浓度(10-8、10-7mol/L)对VSMC增殖无影响,但高浓度(10-6、10-5mol/L)却促进VSMC的增殖[PD128907 10-6mol/L=(4982±529)计数/min、PD128907 10-5mol/L=(5782±483)计数/min与对照=(3798±438)计数/min相比,P<0.05],此作用可被α受体阻断剂酚妥拉明阻断。低浓度的PD128907(10-7mol/L)可通过D3受体减弱NE 10-6mol/L引起的VSMC增殖[NE 10-6mol/L=(6315±245)计数/min与NE 10-6mol/L+PD128907 10-7mol/L=(4898±286)计数/min相比,P<0.05。结论D3受体对NE所致的VSMC增殖具有抑制作用,该作用可能在高血压的发生、发展中发挥作用。     

β_1肾上腺素受体激动对血管平滑肌细胞迁移的影响

目的观察β_1肾上腺素受体(β_1-AR)激动对血管平滑肌细胞(VSMC)迁移的影响。方法选择原代培养的Wistar大鼠胸主动脉VSMC并分7组:5%FBS组(对照组)、去甲肾上腺素(NE)刺激组(A组)、NE+β_1-AR阻断剂组(B组)、异丙肾上腺素(ISO)刺激组(C组)、ISO+β_1-AR阻断剂组(D组)、NE+蛋白激酶A阻断剂组(E组),NE+蛋白激酶抑制剂组(F组)。各组不同条件持续培养24 h后,以细胞划片法观察各组VSMC迁移距离的变化。另选VSMC加入10~(-4)～10~(-7)mol/L浓度NE刺激,观察其对细胞迁移效率的影响。结果与对照组比较,A组、C组VSMC迁移距离明显缩短,差异有统计学意义(P<0.01)。B组、D组迁移距离与对照组比较,差异无统计学意义。随着NE浓度增加,VSMC迁移距离逐渐缩短,NE对于VSMC迁移的抑制效应呈剂量依赖性。F组VSMC相对迁移距离与A组比较,差异无统计学意义。结论β_1-AR激动可抑制VSMC迁移,此过程不依赖蛋白激酶A的激活。     

心力衰竭患者抗β3 肾上腺素能受体自身抗体的分布及特性

目的探讨心力衰竭(心衰)患者血清中的抗β3肾上腺素能受体(β3-AR)自身抗体的生物学效应,为临床治疗心衰提供新的思路和线索.方法 (1)以人β3-AR细胞外第二环的合成肽段作为抗原,采用ELISA筛选正常人和心衰患者血清中抗β3-AR自身抗体.(2)提纯该抗体阳性的患者血清中的IgG.(3)设立各组对照观察该抗体对成年大鼠心肌细胞收缩效应的影响.(4)设立各组对照观察该抗体对乳鼠心肌细胞跳动频率的影响.结果 (1)正常人抗β3-AR自身抗体的阳性率为11.0%,平均滴度为1∶ 14.59±1.61;心衰患者抗β3-AR自身抗体的阳性率为26.7%,平均滴度为1∶ 43.27±2.71;与正常人相比,P＜0.05.(2)与空白对照组相比,该抗体可降低成年大鼠心肌细胞收缩幅度/初长度(3.84%±0.33%)、收缩速率(-0.47 μm/s±0.07 μm/s)和舒张速率(0.17 μm/s±0.02 μm/s),P＜0.05.该作用不能被纳多洛尔(nadolol,β1-AR和β2-AR受体拮抗剂)阻断,但可被布拉洛尔(bupranolol,非特异性β受体拮抗剂)或β3抗原阻断.(3)与空白对照组(94.3次/min±10.7次/min)相比,该抗体可降低乳鼠心肌细胞跳动频率(47.1次/min±8.11次/min),P＜0.05.同样该作用不能被纳多洛尔阻断,但可被布拉洛尔或β3抗原阻断.此外,该抗体的负性变时效应在观察时间内(6 h)无衰减.结论心衰患者血清中含有较高滴度的抗β3-AR自身抗体并具有负性变力和变时效应,提示该抗体可能参与心衰的病理生理机制.     

Norepinephrine induces apoptosis in neonatal rat endothelial cells via down-regulation of Bcl-2 and activation of beta-adrenergic and caspase-2 pathways

OBJECTIVES: Heart failure is associated with increased plasma norepinephrine (NE) and endothelial apoptosis. Recent reports have suggested that endothelial dysfunction is an important target for future therapies of heart failure. However, whether NE can induce endothelial apoptosis and its mechanism remains unknown. METHODS: Endothelial cells from neonatal rat heart were treated with various concentrations of NE for different durations. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL) and DNA fragmentation assays. Caspase activity was measured using specific fluorogenic substrates. Proteins of Bcl-2 family and cytochrome c were assayed by Western blotting. RESULTS: NE induced endothelial apoptosis in a dose- and time-dependent manner. After treatment for 48 h, increasing NE concentration from 5, 10, 50, 100 to 200 microM resulted in 6+/-3%, 14+/-5%, 43+/-4%, 66+/-5%, and 89+/-6% apoptotic cells, respectively. The apoptosis was accompanied by down-regulation of Bcl-2 protein synthesis but not by cytosolic cytochrome c translocation. Caspase-2, -3, -6 and -9 were activated during apoptosis and caspase-2 inhibitor (Z-VDVAD-FMK) and caspase-3 inhibitor (Z-DEVD-FMK) significantly attenuated the apoptosis. Overexpression of Bcl-2 inhibited caspase activity and decreased the apoptosis. Moreover, the NE-mediated apoptotic effect was attenuated by beta- (beta2>beta>beta1) adrenergic antagonists (ICI-118,551>propranolol>atenolol) but was not affected by alpha1- or alpha2-adrenergic antagonists (prazosin or yohimbine). CONCLUSION: Our study is the first report documenting that NE induces apoptosis in neonatal rat endothelial cells mainly through down-regulation of Bcl-2 protein and activation of the beta-adrenergic (beta2>beta1) and caspase-2 pathways. beta-Adrenergic antagonists and caspases inhibitors may be useful in the prevention and management of NE-mediated endothelial apoptosis during heart failure.     

Subtype specific roles of beta-adrenergic receptors in apoptosis of adult rat ventricular myocytes

We have previously reported that beta-adrenergic receptor (beta-AR) stimulation promotes apoptosis in adult ventricular myocytes through PKCepsilon-mediated suppression of ERK. In this study, we investigated differential effects of beta-AR subtypes on this signal pathway. The apoptosis induced by the non-specific beta-AR agonist isoproterenol was largely blocked by the beta(1)-selective antagonist CGP 20712A, but not by the beta(2)-selective antagonist ICI 118551. A pro-apoptotic effect of beta(1)-AR was also blocked by the PKA inhibitor H89, while the protein kinase A (PKA) activators forskolin and dibutyryl-cAMP both induced apoptosis. These results indicate that beta(1)-AR-mediated PKA activation is largely responsible for the apoptosis induced by beta-AR in adult rat cardiac myocytes. This conclusion was also supported by the finding that PKA was preferentially activated by beta(1)-AR over beta(2)-AR. beta(2)-AR selectively induced anti-apoptotic ERK activation in the presence of PKCepsilon suppression, and this ERK activation was sensitive to pertussis toxin. PKCepsilon itself as well as Akt, the other anti-apoptotic factor were activated by both beta-AR subtypes. Thus, beta(1)-AR induces pro-apoptotic signals mainly through PKA activation. In contrast, beta(2)-AR is linked to Gi-mediated ERK activation, which is involved in the anti-apoptotic pathway, and is regulated by PKCepsilon. Therefore, our findings suggest a rather complex role for beta-AR subtypes in the regulation of apoptosis in adult ventricular myocytes.     

Hypocaloric diet reduces exercise-induced alpha 2-adrenergic antilipolytic effect and alpha 2-adrenergic receptor mRNA levels in adipose tissue of obese women

Previous investigations have shown that alpha 2-adrenoceptor (alpha 2-AR) stimulation blunts lipid mobilization during physiological activation of the sympathetic nervous system promoted by exercise in sc abdominal adipose tissue (SCAAT) in obese men. To investigate the effect of a low calorie diet (LCD) on the alpha 2-adrenergic responsiveness and on the expression of alpha 2-AR and beta 2-adrenoceptor (beta 2-AR) in SCAAT, 11 obese women (weight: 99.1 +/- 4.6 kg; body mass index: 34.3 +/- 1.1 kg/m(2)) received a 12-wk diet providing 500 kcal/d less than their usual diet. The exercise-induced alpha 2-adrenergic antilipolytic effect was investigated in SCAAT before and at the end of LCD. Changes in extracellular glycerol concentration and local blood flow were measured in SCAAT during a 45-min exercise bout (50% of heart rate reserve) using a control microdialysis probe and a probe supplemented with the alpha2-AR antagonist phentolamine. SCAAT biopsies were performed for determination of mRNA levels using RT-competitive PCR. Plasma catecholamine responses to exercise bout were not different before and at the end of LCD. Before LCD, the exercise-induced increase in extracellular glycerol concentration was potentiated by phentolamine supplementation, while this potentiating effect of the alpha-antagonist was not observed at the end of LCD. No changes were observed for beta 2-AR and hormone-sensitive lipase mRNA levels, while alpha 2-AR mRNA level was significantly decreased in adipose tissue during LCD. These findings show that alpha 2-AR-mediated antilipolytic action is reduced by a moderate hypocaloric diet and that down-regulation of alpha 2-AR mRNA levels may participate in the decrease of the alpha 2-adrenergic effect revealed by microdialysis.     

Modulation of the pacemaker current If by beta-adrenoceptor subtypes in ventricular myocytes isolated from hypertensive and normotensive rats.

OBJECTIVE: Both beta 1- and beta 2-adrenoceptors (beta 1-AR and beta 2-AR) are functionally present in human and rat ventricular myocytes. The two receptor subtypes are differently regulated during the development of myocardial hypertrophy and failure. I(f) is expressed in human and rat ventricular myocytes. In hypertrophied myocytes isolated from old spontaneously hypertensive rats (SHR) the density is much larger than in age-matched normotensive Wistar Kyoto (WKY). Due to the possible relevance of I(f) as an arrhythmogenic mechanism in the rat and human ventricle, we studied and compared the effects of beta 1-AR and beta 2-AR stimulation on I(f) in both hypertrophied and normal left ventricular myocytes of 18-month old SHR and WKY. METHODS: The whole-cell configuration of the patch-clamp technique was employed. Noradrenaline (NA, 1 microM) was used to stimulate beta 1-AR and isoprenaline (ISO, 1 microM) in the presence of the beta 1-AR antagonist CGP 20712A (0.1 microM) to stimulate beta 2-AR. RESULTS: In SHR, NA increased I(f) by causing a 10.8 +/- 0.9 mV (n = 10) positive shift in the voltage of maximal activation (V1/2); this effect was completely reversed by CGP 20712A. beta 2-AR stimulation was effective in seven out of 13 cells tested, where it caused a small positive shift in V1/2 (4.0 +/- 1.7 mV). Cyclopentyladenosine (CPA), a selective A1-receptor agonist, reversed the effect of NA; the antiadrenergic action of CPA was abolished in cells pre-incubated with pertussis toxin (PTX) to block inhibitory G proteins (Gi). In PTX-treated cells the shift in V1/2 caused by both beta 2-AR (9.6 +/- 1.7 mV, n = 6, p < 0.05) and beta 1-AR (17.6 +/- 1.9 mV, n =7, p < 0.05) was significantly greater than in control cells. Both beta-AR subtypes modulated I(f) activation also in WKY: beta 1-AR shifted V1/2 by 16.0 +/- 1.4 mV (n = 15) and beta 2-AR by 4.2 +/- 1.1 mV (n = 7). However, in PTX-treated WKY cells only the beta 2-AR effect was potentiated (shift in V1/2: 11.4 +/- 1.4 mV, n = 9, p < 0.01), while the beta 1-AR response was unchanged (18.9 +/- 4.2 mV, n = 5, n.s.). CONCLUSIONS: I(f) expressed in SHR hypertrophied ventricular myocytes is modulated by catecholamines mainly through the stimulation of the beta 1-AR subtype. The beta 1-AR response is, however, significantly lower than that observed in myocytes from normotensive rats, probably as a consequence of the presence of an increased inhibitory activity of Gi proteins. This post-receptorial control may be seen as a mechanism to limit the arrhythmogenicity of beta-AR stimulation in myocardial hypertrophy and failure.     

大鼠脾脏收缩功能与α肾上腺素受体亚型的调节

目的:探讨脾脏收缩功能与α肾上腺素受体（α－ＡＲ）及亚型分布的关系。方法:采用药物受体分析方法，测定应用拮抗剂前后，ｐＡ２，ｐＤ２，ＥＣ５０，Ｒｍａｘ的值。结果:①对Ｒｍａｘ的抑制:硝苯吡啶（Ｎｉｆ）＋育亨宾（Ｙｏｈ，４３％）＞哌唑嗪（Ｐｒａｚ，３９％）＞酚妥拉明（Ｐｈｅｎ，２７％）＞Ｙｏｈ（１９％）；②脾脏ＮＥ累积浓度收缩曲线右移程度（在ＥＣ５０水平），Ｐｒａｚ＝Ｎｉｆ＋Ｙｏｈ（３．４倍）＞Ｐｈｅｎ（３．０倍）＞Ｙｏｈ（１．７倍）；③各组均能显著降低ｐＤ２；④ｐＡ２:Ｐｒａｚ，Ｐｈｅｎ，Ｙｏｈ三者间无差异，但它们均显著高于Ｎｉｆ＋Ｙｏｈ组。结论:①大鼠脾脏α受体亚型为α１，α２，且α１略多于α２亚型。②大鼠脾脏α１受体亚型介导收缩效应并不依赖于细胞外Ｃａ２＋的存在。可能α１亚型为α１Ｂ亚型。     

Heightened norepinephrine-mediated vasoconstriction in type 2 diabetes

Adrenergic responsiveness (AR) appears to be increased in subjects with diabetes, but measurement of arterial AR in normotensive people with type 2 diabetes mellitus has not been previously reported. We sought to determine whether, compared with control subjects, there is increased arterial AR in type 2 diabetes mellitus and its relationship to the level of systemic sympathetic nervous system activity (SNSa). We studied 15 type 2 diabetic subjects aged 57 +/- 3 years without hypertension or clinical signs of autonomic neuropathy and 13 age-matched control subjects aged 55 +/- 2 years. We assessed vascular alpha-AR by measuring forearm blood flow (FABF) by venous occlusion plethysmography during intrabrachial artery norepinephrine (NE) and phentolamine infusions, as well as arterial plasma NE levels and the extravascular NE release rate (NE2) derived from 3H-NE kinetics, as estimates of systemic SNSa. The vasoconstricting effect of NE during intrabrachial artery NE infusion was greater in type 2 diabetes compared with control subjects (P = .02). The vasodilating effect of phentolamine was greater in type 2 diabetics compared with control subjects (P = .05), suggesting increased endogenous arterial alpha-adrenergic tone. Arterial plasma NE levels (control v type 2, 1.8 +/- 0.10 v 1.84 +/- 0.14 nmol/L, P = .86) and NE2 (control vtype 2, 11.8 +/- 1.54 v 13.3 +/- 0.89 nmol/min/m2, P = .39) were similar in the two groups. In summary, in type 2 diabetes compared with control subjects, (1) the vasoconstriction response to intraarterial NE is greater, (2) plasma NE and NE2 are similar, suggesting similar levels of systemic SNSa, and (3) arterial alpha-adrenergic tone is greater. We conclude that subjects with type 2 diabetes demonstrate inappropriately increased alpha-AR for their level of systemic SNSa.     

Direct effects of testosterone, 17 beta-estradiol,and progesterone on adrenergic regulation in cultured brown adipocytes: potential mechanism for gender-dependent thermogenesis

Previous studies suggest that sex hormones could be responsible, at least in part, for the gender-dependent thermogenesis found in the adrenergic control of brown adipose tissue (BAT) under control conditions and in response to diet and cold. Catecholamines, as well as several hormones, including sex hormones, may alter the function or expression of different adrenoceptor subtypes in brown adipocytes in vivo, and a confirmation could be provided by in vitro experiments. Therefore, the effect of testosterone, 17 beta-estradiol, progesterone, and norepinephrine (NE) on adrenergic receptor (AR) gene expression (alpha 2A-, beta 1-, -, and beta 3-AR) and lipolytic activity was investigated in differentiated brown adipocytes in culture. We report that the expression of each AR subtype gene was distinctively regulated by NE and sex hormones in brown adipocytes. Testosterone-treated cells had lower lipolytic activity and increased expression of antilipolytic receptors alpha 2A-AR. Both 17 beta-estradiol and progesterone decreased alpha 2A-AR expression and alpha 2A/beta 3-AR protein ratio, but progesterone had higher potency than 17 beta-estradiol, increasing beta-AR levels, mainly beta 3-AR expression, and enhancing lipolysis stimulated by NE. In conclusion, our results support the idea that male and female sex hormones, as a part of the hormonal environment of BAT, have direct and opposite effects on the AR balance and lipolytic activity, and they might play a role in the gender dimorphism for the recruitment process in BAT.