大鼠门静脉α肾上腺素受体亚型的分布及功能

目的:探讨门静脉α肾上腺素受体及亚型的分布及其对门脉循环的调控机制。方法:采用药理受体分析方法,结合离体和整体实验,测定α肾上腺素受体拮抗剂和激动剂应用前后;ｐＡ２,ｐＤ２,ＥＣ５０,Ｒｍａｘ和门静脉压力（ＰＶＰ）。结果:①ＮＥ浓度－收缩曲线均右移,程度为哌唑嗪（Ｐｒａ）４０倍,硝苯吡啶（Ｎｉｆ）２３１．８倍,育亨宾（Ｙｏｈ）４．２倍。②对Ｒｍａｘ的抑制率:Ｎｉｆ８９．１％,Ｐｒａ７１．２％,Ｙｏｈ４１．９％。③与门静脉α受体亲和力（ｐＡ２）:Ｐｒａ８．１９,Ｙｏｈ６．０９,Ｎｉｆ６．０２。④对ＰＶＰ影响:苯福林（Ｐｈｅ）显著升高ＰＶＰ（Ｐ＜０．０５）,Ｐｒａ和Ｎｉｆ显著降低ＰＶＰ（Ｐ＜０．０１）。结论:大鼠静脉α受体亚型分布α１亚型,而α１受体亚型构成中主要以α１ａ为主。它们介导门静脉的收缩效应,调节门脉循环。     

长效硝酸酯对心力衰竭大鼠肺α1、β肾上腺素受体各亚型表达水平的影响

目的 探讨长效硝酸酯对心肌梗死后心力衰竭大鼠心功能和肺α1、β肾上腺素受体（AR）各亚型表达水平的影响。方法 选用雄性Wistar大鼠90只,分为正常对照组（N组,n＝9）、假手术组（SH组,n＝8）,其余73只大鼠结扎左冠状动脉前降支制作心肌梗死后心力衰竭模型,成功44只,分为心力衰竭模型组（HF组,n＝9）、硝酸酯小剂量组（LN组,n＝9）、硝酸酯大剂量组（HN组,n＝9）、阳性药物对照组（奥美沙坦酯,OL组,n＝9）及硝酸酯大剂量联合阳性药物组（HN＋OL组,n＝8）,灌胃法给药6周。超声心动图检测用药前后心功能,逆转录?聚合酶链反应（RT-PCR）和免疫印迹法（Western blot）检测各组肺β1-AR、β2-AR、β3-AR、α1A-AR、α1B-AR及α1D-AR的表达水平。结果 用药后,与HF组比较,HN组、OL组及HN＋OL组左室射血分数（LVEF）显著升高（P＜0.05）。与SH组相比,HF组β1-AR和β3-AR表达水平明显下降（P＜0.05）,α1A-AR、α1B-AR和β2-AR表达水平明显升高（P＜0.05）;与HF组相比,HN组、OL组和HN＋OL组β1-AR、β3-AR表达水平明显升高（P＜0.05）,α1A-AR、α1B-AR及β2-AR表达水平明显降低（P＜0.05）。与OL组相比,HN＋OL组各受体表达水平差异更显著（P＜0.05）。各组大鼠α1D-AR表达水平间差异无统计学意义（P＞0.05）。结论 应用长效硝酸酯药物可显著提高心肌梗死后心力衰竭大鼠LVEF,使心力衰竭大鼠肺α1、β-AR各亚型表达水平反向调节趋于正常,对保护肺功能起到了有益的治疗作用。     

选择性β1受体阻滞剂对高血压病患者β受体亚型功能的调节特性

目的探讨选择性β１受体阻滞剂对人体心肌β受体亚型功能的影响。方法采用踏车运动法与羟甲叔丁肾上腺素药物试验，测定２０例连续接受选择性β１受体阻滞剂治疗４个月以上的高血压病男性患者，停药后３天峰运动功率心率最大增加值（β１受体反应性）与羟甲叔丁肾上腺素（选择性β２受体激动剂）增加心率３０次／分的变时剂量（ＣＤ３０，β２受体反应性）；２０例至少４个月内未服用β受体阻滞剂的高血压病男性患者予以同期测定，以作对照。结果峰运动功率心率最大增加值选择性β１受体阻滞剂治疗组为８８．１±１０．５次／分，比非β受体阻滞剂治疗组（７８．５±９．４次／分）无明显差异（Ｐ＞０．０５）；静脉注射羟甲叔丁肾上腺素ＣＤ３０选择性β１受体阻滞剂治疗组为１．８±０．３μｇ／ｋｇ，比非β受体阻滞剂治疗组（２．７±０．２μｇ／ｋｇ）显著降低（Ｐ＜０．００１）。结论选择性β１受体阻滞剂具有交叉选择性提高心肌β２受体功能的生物学特性，这可能是β受体阻滞剂停药综合征的细胞学机制。     

心力衰竭大鼠肾脏α_1及β肾上腺素受体各亚型表达的改变

目的探讨大鼠心力衰竭时肾脏α_1肾上腺素受体(α_1-AR)和β肾上腺素受体(β-AR)各亚型表达水平的变化。方法选择雄性Wistar大鼠35只,随机分为对照组10只、假手术组10只,其余大鼠制作心肌梗死后心力衰竭模型,成功9只为模型组。取大鼠肾脏皮质,采用Western blot法分别测定各组大鼠α_1-AR亚型(α_(1)-AR、α_(1B)-AR、α_(1D)-AR)和β-AR亚型(β_1-AR、β_2-AR)表达水平。结果与假手术组比较,模型组大鼠α_(1A)-AR、β_1-AR表达明显下调,差异有统计学意义(P<0.01);各组大鼠α_(1B)-AR、α_(1D)-AR、β_2-AR比较,差异无统计学意义(P>0.05)。结论心力衰竭时肾脏α_(1A)-AR和β_1-AR明显下调,可能与交感神经系统激活有关;而β_2-AR表达水平无明显变化,可能为代偿β_1-AR下调带来的不利影响,以维持肾脏有效灌注,保护肾脏功能。     

β1肾上腺素能受体阻断剂与β2肾上腺素能受体激动剂联用对心力衰竭大鼠心功能及心肌细胞凋亡的影响

目的 在一定范围内激活β2肾上腺素能受体（AR）可以在不加重心室重构的前提下改善心力衰竭（心衰）大鼠心功能,推测β1AR阻断剂联合β2AR激动剂有可能进一步改善心衰大鼠心功能并减轻心肌细胞凋亡,该实验对此进行了研究并探讨了其机制。方法 随机选取9只雄性Wistar大鼠为对照组。将异丙基肾上腺素诱导的心衰大鼠随机分为美托洛尔组（n=11）,联合治疗组（n=11）,安慰剂组（n=10）。美托洛尔组给予美托洛尔50mg／kg,一日两次灌胃。联合治疗组给予非诺特罗125μg／kg,美托洛尔50mg／kg一日两次灌胃。安慰剂组给予等量生理盐水一日两次灌胃。对照组不予处理。治疗8周后应用超声心动图评价心功能,TUNEL法检测心肌细胞凋亡指数,测定Caspase-3酶活性,Westernblot测定bcl-2及bax蛋白质表达,测定脏器重量／体重,组织病理学测定胶原容积分数（CVF）。结果 （1）美托洛尔组及联合治疗组均较安慰剂组左室舒张末期直径（LVEDd）、左室收缩末期直径（LVESd）、E峰A峰比值（E／A）明显下降,短轴缩短率（FS）、射血分数（EF）则有明显增高。联合治疗组较美托洛尔组LVEDd、LVESd有进一步降低（均为P〈0．05）,FS、EF则有进一步增高（均为P〈0．01）。（2）美托洛尔组及联合治疗组较安慰剂组左室重量体重比（LVW／BW）、肺脏重量体重比（PW／BW）及CVF明显降低（均为P〈0．01）。联合治疗组LVW／BW及PW／BW较美托洛尔组进一步降低（P〈0．01）,但两组之间CVF无显著差异。（3）美托洛尔组及联合治疗组较安慰剂组心肌细胞凋亡指数（AI）及Caspase．3活性均有明显减低。联合治疗组较美托洛尔组有进一步减低（均为P〈0．01）。（4）与安慰剂组相比,美托洛尔组及联合治疗组bax蛋白表达有明显下降而bcl-2／bax显著升高,并且以联合治疗组改善更为显著（均为P〈0．01）。结论 β1AR阻断剂联合β2AR激动剂较单用β1AR阻断剂进一步改善心衰大鼠的心功能,减轻心室重构。明显降低bax蛋白表达及bcl-2／bax,减轻心肌细胞凋亡很可能是其疗效提高的机制之一。     

慢性充血性心力衰竭患者循环血细胞α_2、β肾上腺素能受体功能

本文分别用血小板α_2受体和淋巴细胞β受体研究中枢神经和交感末梢突触前α_2受体和心肌β受体的功能状态。结果提示:中枢神经和交感末梢突触前α_2受体功能降低是心衰交感张力增高的原因之一;心肌β受体由于交感张力增高而向下调节,导致功能降低。     

肝硬化门脉高压鼠脾脏舒缩功能改变与α肾上腺素受体变化的关系

目的 :探讨脾脏舒缩功能改变与α受体调控改变的关系。方法 :采用药理学受体分析技术 ,测定两组大鼠脾脏α受体在应用拮抗剂前后 ,PA2 ,PD2 ,KA,EC5 0 ,Rmax,q值受体占有率等。结果 :肝硬化门脉高压鼠的脾脏α受体对去甲肾上腺素的亲和力、敏感性、受体占有率及脾脏收缩效应均显著低于正常鼠 ,但α储备受体都高于正常鼠。结论 :门脉高压鼠脾脏α受体处于“低敏状态”,脾脏舒张功能强于收缩的失衡状态 ,导致脾脏充血肿大。因此 ,肝硬化门脉高压情况下脾脏“低敏状态”的α受体可能是导致脾脏充血性肿大的原因之一。     

自发性高血压大鼠心脏血管紧张素Ⅱ受体与β肾上腺素受体的交互作用

目的　研究 14周龄自发性高血压大鼠 (SHR)与 14周龄SD大鼠心脏血管紧张素Ⅱ (AngⅡ )受体与β肾上腺素受体 (β AR)之间的交互作用。 方法　采用放射免疫法测定异丙基肾上腺素 (Iso)及AngⅡ诱导的环磷酸腺苷(cAMP)、环磷酸鸟苷 (cGMP)蓄积水平 ;采用体外左心房收缩功能实验观察AngⅡ对Iso激动 β AR介导正性变力效应的影响。结果　 14周龄SHR ,基础cAMP水平明显降低 ,Iso刺激后两组大鼠心脏cGMP水平明显下降 ,cAMP水平明显升高 ,AngⅡ加Iso联合刺激后cAMP水平更明显升高 ;AngⅡ使SD大鼠心脏 (n =6 )最大收缩效应增强。结论　AngⅡ对Iso诱导的心脏cAMP蓄积有明显的正协同作用 ;AngⅡ可增强SD大鼠心脏Iso激动 β AR介导的正性变力效应 ,而在SHR这种增强作用消失。     

Effects of endurance training on cholinergic and adrenergic receptors of rat heart

To test the hypothesis that alterations in adrenergic or cholinergic receptors occur in response to physical training, and that changes in receptor properties could be mechanistically important in producting the altered cardiovascular physiology of the trained state, we studied the effects of endurance training by swimming upon beta adrenergic, alpha adrenergic, and muscarinic cholinergic receptors of rat heart. Because of previously reported sex-related differences in the cardiac adaptation to training, male and female rats were studied separately. Despite the occurrence of demonstrable training bradycardia in males, and of cardiac hypertrophy in females, there were no discernible effects of the training program upon the properties of cardiac beta adrenergic receptors. However, hearts from swimmers of both sexes demonstrated fewer numbers of muscarinic cholinergic and alpha adrenergic receptors than sedentary controls, without differences in the receptor affinities for antagonist or agonist compounds. These findings are inconsistent with the hypothesis that altered cardiac sensitivity to neurotransmitters contributes directly to training bradycardia.     

Decreased alpha-adrenergic constriction of renal preglomerular arteries occurs with age and is gender-specific in the rat

Age and/or gender appear to moderate alpha-adrenergic mediated constrictor mechanisms found in the interlobar arteries of the Munich Wistar rat. We have determined the extent of constriction to alpha-adrenergic receptor stimulation using norepinephrine, phenylephrine and A61603 (α_1A-adrenergic receptor agonist) as a function of age and gender. Norepinephrine produced less constriction in male-derived arteries at ages greater than eight months as compared to the younger adult male (four to six months). The arteries derived from females did not demonstrate altered constriction until greater than 15 months of age. Similarly, arteries derived from the male demonstrated weaker constrictions to phenylephrine (10⁻⁶ to 10⁻³ M) at ages greater than eight months while arteries from females showed differences at greater than 15 months. In contrast, the effective concentration of norepinephrine to cause a 50% maximal constriction (EC₅₀) was significantly less in the four to five-month-old male rats compared to the pooled data from older groups. Interestingly, four to five month old males had A61603 EC₅₀ values similar to the 8 to 12-month and 15+ old females. These studies conclude that an age related loss of sympathetic α-adrenergic constriction of renal interlobar arteries is present in Munich Wistar rats. Furthermore, this loss, while similar along longitudinal aspects of age, is also different as a function of gender with the loss of α-adrenergic constrictor function delayed in the female when compared to the male.     

Relationship between hepatocellular carcinoma and subtypes of hepatitis C virus: A nationwide analysis

Although hepatitis C virus (HCV) has now been classified into several subtypes, the clinical significance of HCV subtypes is not well known. Typing of HCV is now routinely performed in Japan. In the present study, HCV subtypes in hepatocellular carcinoma (HCC) patients were analysed from nationwide data collected in Japan using a standard questionnaire. Answers to the questionnaire concerning HCV subtypes in patients with chronic hepatitis (CH), liver cirrhosis (LC) and HCC were obtained from 14 hospitals. The prevalence of the 1b-related subtype, which includes the mixed subtype of 1b and 2a or 2b, in patients with LC and HCC in each hospital was higher than in patients with CH, with few exceptions. However, the differences were not statistically significant because of the small number of patients in each hospital. In summarized data from all 14 hospitals, the 1b-related subtype was found in 1370 of 1922 patients with CH (71.2%). In 356 LC and 426 HCC patients, the prevalence of the 1b-related subtype was 79.8 and 80.5%, respectively. The prevalence of the 1b-related subtype in patients with LC and HCC was significantly higher than in patients with CH. There was no significant difference between the prevalence of the 1b-related subtype in patients with HCC and LC. These results indicate that the oncogenic activity of subtype 1b, although not yet clearly characterized, may be stronger than subtypes 2a and 2b.     

Cardiac alpha- and beta-adrenergic receptor alterations in diabetic cardiomyopathy

Summary The effect of chronic experimental diabetes on the adrenergic receptors in the rat heart was investigated. Diabetes was induced by streptozotocin (65 mg/kg; i.v.) administration, animals were sacrificed 8 weeks later, and positive as well as negative dF/dt values were determined in isolated papillary muscle preparations. Stimulation of the contractile force generation by isoproterenol and methoxamine was attenuated in diabetic preparations. Beta-and alpha-adrenergic receptor bindings were determined in cardiac membranes by employing³H-dihydroalprenolol and³H-dihydroergocryptine respectively. Reduced number of beta- and alpha-receptor binding sites without changes in the affinity constants were observed in diabetic myocardium. Such a decrease in alpha- and beta-receptor density in the heart may account for the depressed contractile responsiveness to adrenergic stimuli in diabetic cardiomyopathy.

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Zusammenfassung Es wurde der Einfluß eines chronischen, experimentellen Diabetes auf die adrenergen Rezeptoren des Rattenherzens untersucht. Diabetes wurde durch Streptozotocin (65 mg/kg i.v.) erzeugt. Die Untersuchungen wurden 8 Wochen nach Verabreichung durchgeführt. Es wurden positive und negative dF/dt-Werte (Geschwindigkeit der Kraftentwicklung) von isolierten Papillarmuskeln bestimmt. Die durch Isoproterenol und Methoxamin gesteigerte Kraftentwicklung war bei Ratten mit Diabetes vermindert. Die Bindungseigenschaften von Beta-und Alpha-rezeptoren in den Membranen des Herzens wurden mit Hilfe von³H-dihydroalprenolol und³H-dihydroergocryptin bestimmt. Im diabetischen Myokard war die Zahl der Beta- und Alpharezeptor-Bindungsstellen vermindert, nicht jedoch die Affinitätskonstanten. Die verringerte Beta- und Alpharezeptoren-Dichte im Herz könnte für die verminderte Ansprechbarkeit der Mechanik auf adrenerge Reize bei der diabetischen Kardiomyopathie verantwortlich sein.

     

Relationship between Insulin binding and glycogenesis in cultured fetal hepatocytes

Summary Binding of ¹²⁵I-insulin and the stimulatory effect of insulin on ¹⁴C-glucose incorporation into glycogen have been studied in cultured fetal rat hepatocytes. Measurement of both variables was possible at 37 °C because of the slow rate of insulin degradation in the medium. ¹²⁵I-insulin binding approached maximum after 10 min, thus largely preceding the insulin glycogenic effect which became significant after 45 min. Maximal effect was observed after 3 h with 10 nmol/l insulin when 16,000 specific sites per hepatocyte were occupied and half-maximal response was achieved with 0.3 nmol/l insulin (2,900 sites/hepatocyte). Dissociation of bound insulin was rapid (t1/2=3 min) and accelerated by the availability of native insulin. In hepatocytes preincubated with insulin, binding was measured after 30 min incubation in the absence of hormone which allowed the liberation of most (95%) of the bound insulin. No modification of insulin binding was observed over extended periods (2–24 h) of exposure to 10 nmol/l insulin, when the glycogenic effect of insulin showed striking variations, notably a cessation of the effect between 4 and 12 h. Thus the time-dependence of the glycogenic effect of insulin cannot be related to a defect in insulin binding in cultured fetal hepatocytes.     

Transvascular fluid shifts following single injections of catecholamines in the alert rat: comparison of the effects of adrenalin,noradrenalin and stimulated activity

Summary Single injections of noradrenalin and adrenalin were made into the v. cava of conscious rats during continuous registration of arterial blood pressure and conductivity (reciprocal hematocrit) in blood from different circulatory areas. The resulting hct and B.P. changes were compared with similar changes elicited by a 3-sec tactile stimulus. Two phases of hct response—the first due to local vascular reactions, the second due to a general vasodilatory reaction—can be distinguished. Whereas adrenalin and noradrenalin show differential effectivity in producing the local reactions (the former more potent as a precapillary vasoconstrictor, promoting hct drop due to fluid inflow in the portal and hepatic vein, the latter more so in the renal vein and the aorta), adrenalin is invariably more effective in producing the second phase dilatory reaction with fluid outflow (hct rise). In the v. cava close to the iliac bifurcation a greater hemoconcentrative potency of adrenalin can be demonstrated, but only by close injections into the aorta. Close injections into the portal vein make postcapillary hepatic reactions more sensitive to adrenalin manifest. The catecholamine dose equivalent to a 3-sec tactile stimulus in the rat is 80–120 ng.Supported by DFG-Grant AZ 3/3     

Further validation of the epinephrine pathophysiology rat model of Takotsubo syndrome

The pathophysiology of Takotsubo syndrome (TTS), the reversible cardiomyopathy affecting mainly the left ventricle, with primarily apical and midventricular “ballooning” and basal hypercontractility, continues to be elusive. Many etiological hypotheses have been advanced with a pivotal recent one, which has attributed the TTS to a switch of the function of the beta-2 adrenergic receptors from the canonical cardiostimulatory to cardiodepressant mode, engendered by large doses of epinephrine administration. This worthy animal model has not been explored to its fullest, and thus the author of this viewpoint proposes a series of essential experimental enhancements, in order for the model to provide additional indirect insights, pertaining to the pathophysiology of TTS in humans.     

Protection of rats against malaria by a transplanted immune spleen

A number of reports have suggested that the spleen plays a key role in the regulation of immunity to malaria but the role, if any, of other tissues is less clear. Furthermore, numerous functional changes occur in the spleen following malaria infection and it is not known whether the spleen's role relates primarily to its content of malaria-specific lymphocytes or to the altered structure and function that has occurred. To address these issues we have generated splenic chimeras by transplanting spleens between Plasmodium berghei -immune and naive rats. In the absence of a functional spleen, specific immune responses from both isolated splenic and non-splenic cells can partially control infection. However, an immune spleen in a naive rat can solidly protect the animal from malaria and a normal spleen in an otherwise immune rat can provide enhanced protection over the non-splenic state. Thus, in the presence of functional splenic architecture both splenic and non-splenic malaria-specific lymphocytes operate more effectively. However, these studies do demonstrate an important role for non-splenic tissue in immunity at least for P. berghei in the rat. The study could have important implications for induction of protective immune responses by vaccination and suggests that malaria-specific lymphocyte responses induced in the periphery following vaccination could interact with parasites in both spleen-dependent and spleen-independent ways.