甲状腺素对大鼠慢性心衰细胞收缩功能及钙瞬变的影响

目的研究甲状腺素对心力衰竭大鼠的单个心肌细胞收缩功能及钙瞬变的影响。方法采用腹主动脉缩窄法建立大鼠心力衰竭模型,随机分为心衰组与甲状腺素治疗组,另设假手术对照组。术后16周测定心功能。各组分离单个心室细胞,采用可视化动缘探测系统同步检测大鼠心肌细胞收缩和钙瞬变的变化。结果①甲状腺素治疗组左室收缩压（LVSP）和±dp/dtmax较CHF组明显提高（P<0.05）,左室舒张末压（LVEDP）较CHF组明显下降（P<0.05）。②甲状腺素治疗组单个心肌细胞收缩功能指标最大收缩幅度（PTA）、最大缩短和复长速率（±dL/dtmax）较CHF组明显增加（P<0.05）,钙瞬变指标fura-2荧光强度变化（ΔFFI）增强、Ca2+离子达峰值时程（TTPCa）、舒张期Ca2+减少50%时程（T50DCa）较CHF组明显缩短（P<0.05）。结论甲状腺素可改善大鼠单个心衰细胞的收缩功能及钙瞬变幅度,在单细胞水平上为探讨甲状腺素治疗慢性心衰的发生机制提供了实验依据。     

糖尿病树鼩血栓性脑缺血时心脏血流动力学及心肌超微结构的变化

目的观察实验性糖尿病树鼩在血栓性局部脑缺血时心脏血流动力学及心肌超微结构的变化。方法链脲佐菌素(STZ)55mg/kg空腹腹腔注射制备糖尿病树鼩模型,一周后通过光化学反应诱导局部血栓性脑缺血。将树鼩随机分为糖尿病组,脑缺血组,糖尿病加脑缺血组,并设假手术对照组,每组8只,用多导生理仪观察左心室内压(LVSP)、左心室舒张末压(LVEDP),左心室收缩与舒张瞬间变化最大速率(±dp/dtmax),收缩动脉压(SAP),舒张动脉压(DAP)及心率(HR)。并取左心室心肌组织,行透射电镜观察心肌超微结构变化。结果 与假手术对照组相比,脑缺血组LVSP、+dp/dtmax下降(P<0.05),-dp/dtmax明显下降(P<0.01),LVEDP升高(P<0.05);糖尿病组-dp/dtmax下降(P<0.05),LVEDP明显升高(P<0.01)。与脑缺血组相比,糖尿病加脑缺血组LVSP、+dp/dtmax降(P<0.05),-dp/dtmax明显下降(P<0.01),LVEDP升高(P<0.05)。脑缺血组和糖尿病组心肌超微结构观察显示:心肌肌原纤维间水肿,一些肌原纤维可见收缩小带形成,部份线粒体固缩,部份线粒体肿胀。糖尿病加脑缺血组树鼩可见:大部分线粒体固缩,部分线粒体肿胀、嵴溶解,心肌纤维较多收缩带形成,间质充血水肿,毛细血管内皮细胞见较多空泡。结论树鼩血栓性脑缺血时伴有心脏血流动力学及心肌超微结构的异常,糖尿病急     

甲状腺素对心力衰竭大鼠心功能及心肌细胞钠-钙交换体表达的影响

目的:研究甲状腺素对心力衰竭大鼠的心功能及心肌细胞钠-钙交换体(NCX1)表达水平的影响。方法:SD 大鼠120只随机分为对照组(40只)、心力衰竭组(40只)和心力衰竭治疗组(40只)。通过缩窄主动脉复制心力衰竭动物模型,测定血流动力学指标,应用免疫组织化学及Western blot研究NCX1的表达水平。结果:(1)心力衰竭组左室收缩压(LVSP)和±dp/dtmax较对照组明显降低(P<0.01),甲状腺素治疗组LVSP和±dp/dtmax较对照组降低(P<0.05),但甲状腺素治疗组LVSP和±dp/dtmax较心力衰竭组明显升高(P<0.01);心力衰竭组左室舒张末压(LVEDP)较对照组明显升高(P<0.01),甲状腺素组LVEDP较心力衰竭组明显下降(P<0.01);(2)免疫组化单位面积(200倍视野/0.442mm2)内NCX1阳性颗粒数对照组(8.3±1.5)个,心力衰竭组为(24.1±4.5)个,甲状腺素治疗组为(15.6±2.9)个,各组间有显著性差异(P<0.01);(3)Western blot分析灰度峰值对照组13.7±2.4, 心力衰竭组为32.4±5.5,甲状腺素治疗组为20.2±3.9,各组间有显著性差异(P<0.001)。结论:甲状腺素可能通过抑制NCX1的过渡表达而发挥改善心力衰竭时心功能的作用。     

Rho激酶信号通路与大鼠心肌细胞凋亡的关系

目的探讨Rho激酶信号通路在心肌梗死模型大鼠心肌细胞凋亡组织中的表达变化及对心肌细胞凋亡的影响作用。方法选取健康雄性Wistar大鼠,通过结扎左前降支建立大鼠心肌梗死模型,将24 h后仍然存活的大鼠选取30只,随机分为模型组和治疗组(法舒地尔5 mg/kg,2次/d)各15只,并另外选取健康雄性大鼠15只作为假手术组,假手术组和模型组给予等量生理盐水处理,比较4 w后3组心肌梗死面积及Rho激酶mRNA、蛋白等指标的表达差异。结果 3组左心室收缩压(LVSP)、左室舒张压(LVEDP)、左室内压最大上升速率(+dp/dtmax)、左室内压最大下降速率(-dp/dtmax)差异均有统计学意义(P0.05),模型组LVSP、+dp/dtmax、-dp/dtmax显著低于治疗组和假手术组(P0.05),LVEDP显著高于治疗组和假手术组(P0.05),治疗组LVSP、+dp/dtmax、-dp/dtmax显著低于假手术组(P0.05),LVEDP显著高于假手术组(P0.05)。治疗组心肌缺血面积低于模型组但差异不显著(P0.05);治疗组心梗面积显著低于模型组(P0.05)。3组Rho激酶mRNA、Bax蛋白、Bcl-2蛋白表达差异有统计学意义(P0.05);组间差异均有统计学意义(P0.05)。结论心肌梗死大鼠心肌组织中的Rho激酶mRNA、Bax蛋白达显著增加,同时Bcl-2蛋白表达降低,法舒地尔能够降低Rho激酶mRNA表达,减少心肌细胞凋亡,减轻心肌梗死面积。     

曲美他嗪干预对心力衰竭大鼠心肌细胞线粒体超微结构、心肌细胞凋亡及半胱氨酸天冬氨酸蛋白酶3蛋白、细胞色素C蛋白表达的影响

目的:探讨曲美他嗪干预对心力衰竭(心衰)大鼠左心室心肌细胞线粒体超微结构、心肌细胞凋亡及半胱氨酸天冬氨酸蛋白酶3(caspase-3)蛋白和细胞色素C蛋白表达的影响。方法:雄性wistar大鼠30只随机分为假手术组、心衰模型组、曲美他嗪组,每组10只。除假手术组外,其余两组大鼠采用肾上腹主动脉缩窄法建立慢性心衰模型,其中曲美他嗪组大鼠给予曲美他嗪10 mg/(kg·d)灌胃4 w。观察各组左心室舒张末期压(LVEDP)、左心室压力最大上升及下降速率(±dp/dtmax);苏木素伊红(HE)染色法观察大鼠心肌细胞形态结构;透射电镜观察心肌细胞线粒体超微结构;原位缺口末端标记(TUNEL)法检测心肌细胞凋亡指数(AI);SP免疫组织化学法检测各组大鼠左心室心肌细胞caspase-3蛋白、细胞色素C蛋白的表达。结果:与假手术组比较,心衰模型组大鼠心肌细胞线粒体形态发生明显改变,排列紊乱,空泡变性,LVEDP显著升高(P<0.01),±dp/dtmax明显降低(P<0.01),心肌细胞凋亡指数、caspase-3蛋白及细胞色素C蛋白的表达水平升高,差异均有统计学意义(P<0.01);与心衰模型组相比,曲美他嗪组大鼠心肌细胞线粒体形态变化明显改善,LVEDP明显下降(P<0.01),±dp/dtmax显著升高(P<0.01),心肌细胞凋亡指数、caspase-3蛋白及细胞色素C蛋白的表达水平降低,差异均有统计学意义(P<0.01)。结论:曲美他嗪可有效改善心功能,抑制心肌细胞凋亡,其机制可能与保护心肌细胞线粒体功能有关。     

益气活血药对腹主动脉结扎术后早期心功能不全大鼠血流动力学的干预作用研究

目的研究丹参等活血药对心功能不全大鼠的血流动力学的干预作用。方法腹主动脉结扎造模术后的SD大鼠,随机分为假手术组(正常组)、模型组、中药组、西药组、中西医结合组。模型组和正常组给予生理盐水灌服。中药组给予活血药浸膏,西药组给予卡托普利,中西医结合组给予中药联合卡托普利片灌胃,治疗4周和8周后检测血流动力学。包括左室收缩压(LVSP)、左室舒张末压(LVEDP)、左室内压上升下降最大速率(±dp/dtmax)、心率(HR)、外周平均动脉压(MBP)等。结果中药和卡托普利干预治疗4周后,中西医结合组LVSP、LVEDP明显低于模型组(P0.05或P0.01),而舒张末期最大下降速率(-dp/dt)明显高于模型组(P0.01)。中西医结合组治疗8周后LVEDP明显低于模型组((P0.01);而+dp/dtmax、-dp/dtmax明显高于模型组(P0.01)。结论丹参等活血药方与西药卡托普利的联合使用能显著改善心功能不全大鼠的血流动力学,从而对心脏具有一定的保护作用。     

缬沙坦对阿霉素致心肌损伤大鼠心肌结构改变的影响

目的研究缬沙坦对阿霉素(adriamycin,ADR)致大鼠心功能损伤及心肌结构改变的保护作用。方法大鼠腹腔注射ADR(20mg/kg)造成心脏损伤模型。观察缬沙坦对ADR致心肌损伤大鼠体重、左心室功能、血清超氧化物歧化酶(SOD)、肌酸激酶同工酶(CK-MB)和丙二醛(MDA)的变化。结果①ADR组大鼠血清CK-MB活性和MDA含量及左心室舒张末期压(LVEDP)较对照组明显增加;血清SOD、左心室收缩压(LVSP)、左心室等容收缩期压力变化速率最大值( dp/dtmax)显著降低;电镜下可见,ADR组大鼠心肌细胞严重损伤,心肌纤维溶解,肌质网扩张空泡化,线粒体水肿,嵴断裂。②缬沙坦 阿霉素组大鼠CK-MB活性和MDA含量及LVEDP显著降低;SOD和 dp/dtmax显著升高;电镜下可见,局灶性的心肌细胞肌浆溶解;散在性的心肌细胞空泡样变。结论缬沙坦可减轻自由基对心脏的损伤,改善ADR致心肌损伤的毒性反应,并能有效地防治心功能损伤。     

卡维地洛对急性心肌梗死大鼠血流动力学和心肌胶原含量的影响

目的研究卡维地洛(Carvedilol)对大鼠急性心肌梗死(AMI)后血流动力学的影响及其与心肌组织中胶原含量的关系。方法23只AMI术后存活的雄性SD大鼠随机分为AMI对照组(n=11)和卡维地洛治疗(Carvedilol)组(n=12),另设假手术组(n=11)。给药6周后测量室间隔超声背向散射参数(平均背向散射积分标化值IBS%,背向散射积分周期变化值CVIB)及血流动力学参数、心功能指标。结果(1)与假手术组相比,AMI组大鼠SBP、DBP、LVSP及±dp/dtmax及其校正值(±dp/dtmax/LVSP)均显著降低,LVEDP显著增高,高频超声检测显示IBS%显著升高,CVIB显著降低(均为P<0.05)。(2)与AMI组相比,Carvedilol治疗组大鼠SBP、DBP及LVSP均未进一步降低(P>0.05),LVEDP显著降低,±dp/dtmax及其校正值(±dp/dtmax/LVSP)显著升高,高频超声检测显示IBS%显著降低,CVIB显著升高(均P<0.05)。结论第3代β受体阻滞剂Carvedilol的干预有助于恢复AMI大鼠受损的左室功能,这可能与其抑制非梗死区心肌胶原过度沉积有关。     

温补心阳和肾阳方对心力衰竭大鼠心功能和心肌磷酸腺苷含量的影响

目的研究温补心阳和肾阳方对心力衰竭大鼠心功能和心肌磷酸腺苷含量的影响。方法采用结扎冠状动脉前降支术制备心力衰竭大鼠模型,用温补心阳和温补肾阳方于术后2周灌胃,以假手术组为空白对照组,曲美他嗪为阳性药物对照组。给药8周,采用酶联免疫吸附法检测心梗后心力衰竭大鼠药物干预前后脑钠肽(BNP)水平,测定治疗后血流动力学改变,包括心率(HR)、左室收缩压(LVSP)、左室舒张压(LVEDP)、左室内压上升下降最大速率(±LVdp/dtmax),并行高效液相法测定心肌组织中AMP、ADP、ATP的含量。结果对心力衰竭大鼠心功能的影响,温补心阳和肾阳组较模型组,显著降低BNP水平(P<0.01),改善心肌收缩、舒张功能。而肾阳组大鼠LVSP、+LVdp/dtmax较心阳组升高(P<0.05),LVEDP、-LVdp/dtmax、HR、BNP较心阳组降低(P<0.05)。对心力衰竭大鼠心肌磷酸腺苷含量的影响:温补心阳和肾阳组大鼠较模型组心肌AMP、ADP降低(P<0.05),ATP含量升高,而肾阳组大鼠心肌ATP含量显著高于模型组(P<0.01),较心阳组更接近曲美他嗪和假手术组。结论温补心阳和温补肾阳可改善心力衰竭大鼠能量代谢,提高心功能,其中以温补肾阳作用更显著。     

丹参素异丙酯对慢性缺氧大鼠血压和左心室功能的影响

目的: 研究丹参素异丙酯对缺氧大鼠左心室功能的影响。方法: 制备慢性缺氧大鼠模型,分别用大、小剂量的丹参素异丙酯灌胃,设立维拉帕米阳性对照组和正常对照组,采用大鼠心导管插入的方法,测定大鼠血流动力学和心功能指标,观察不同剂量丹参素异丙酯对慢性缺氧大鼠左室心功能的影响。结果: 与正常组比较,单纯模型组的动脉收缩压（SBP）、动脉舒张压（DBP）、平均动脉压（MBP）、左室收缩压（LVSP）、最大上升速率（+dp/dtmax）和最大下降速率（-dp/dtmax）显著升高（P<0.05或P<0.01）,T值(t-dp/dtmax)显著降低（P<0.05）,HE染色显示,心肌细胞出现肌纤维断裂、溶解,细胞核固缩、溶解。与单纯模型组比较,小剂量组的DBP、MBP、心率(HR)、左室舒张末压(LVEDP)和-dp/dtmax显著降低（P<0.05或P<0.01）,T值显著升高（P<0.05）;大剂量组的SBP、DBP、MBP、HR、LVEDP、左室舒张压(LVDP)、+dp/dtmax和-dp/dtmax显著降低（P<0.05或P<0.01）,T值显著升高（P<0.01）;HE染色显示,大、小剂量组心肌细胞内糖元含量丰富,肌纤维排列相对规则,未见明显的肌纤维断裂、溶解及核分裂。与阳性对照组比较,小剂量组的DBP、MBP、LVSP、LVDP和T值显著升高（P<0.05或P<0.01）,LVEDP显著降低（P<0.05）;大剂量组的DBP和T值均显著升高（P<0.05或P<0.01）,LVDP、LVEDP和+dp/dtmax均显著降低（P<0.05或P<0.01）。与小剂量组比较,大剂量组的LVDP、LVEDP和+dp/dtmax均显著降低（P<0.01）。结论: 丹参素异丙酯对慢性缺氧造成的大鼠血压升高、心率加快、心功能亢奋等有明显的抑制作用,因而对缺氧大鼠的心功能有明显的保护作用。     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Serological survey of HIV and syphilis in pregnant women in Madagascar

Objectives Peripartal transmission of human immunodeficiency virus (HIV) and Treponema pallidum, the causative agent of syphilis, leads to severe consequences for newborns. Preventive measures require awareness of the maternal infection. Although HIV and syphilis testing in Madagascar could be theoretically carried out within the framework of the national pregnancy follow‐up scheme, the required test kits are rarely available at peripheral health centres. In this study, we screened blood samples of pregnant Madagascan women for HIV and syphilis seroprevalence to estimate the demand for systemic screening in pregnancy. Methods Retrospective anonymous serological analysis for HIV and syphilis was performed in plasma samples from 1232 pregnant women that were taken between May and July 2010 in Ambositra, Ifanadiana, Manakara, Mananjary, Moramanga and Tsiroanomandidy (Madagascar) during pregnancy follow‐up. Screening was based on Treponema pallidum haemagglutination tests for syphilis and rapid tests for HIV, with confirmation of positive screening results on line assays. Results Out of 1232 pregnant women, none were seropositive for HIV and 37 (3%) were seropositive for Treponema pallidum. Conclusions Our findings are in line with previous studies that describe considerable syphilis prevalence in the rural Madagascan population. The results suggest a need for screening to prevent peripartal Treponema pallidum transmission, while HIV is still rare. If they are known, Treponema pallidum infections can be easily, safely and inexpensively treated even in pregnancy to reduce the risk of transmission.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.     

Variabilité des concentrations plasmatiques de l’angiotensinogène et risque d’hypertension artérielle chez le rat transgénique

Aim

Genetic polymorphisms of the human angiotensinogen gene are frequent and may induce up to 30% increase of plasma angiotensinogen concentrations with a blood pressure increase of up to 5 mmHg. Their role for the pathogenesis of human arterial hypertension remains unclear. High plasma angiotensinogen levels could increase the sensitivity to other blood pressure stressors.

Methods

Male transgenic rats with a 9-fold increase of plasma angiotensinogen concentrations and male non-transgenic rats aged 10 weeks were treated or not with NG-Nitro-L-arginine-methyl ester for 3 weeks in their drinking water (n = 3/group). Systolic blood pressure and body weight were measured at baseline and at the end of the study when left ventricular weight and ventricular expression of angiotensin I-converting enzyme and procollagen Iα1 were determined (polymerase chain reaction).

Results

At baseline, transgenic rats had +18 mmHg higher bood pressure and –8% lower body weight compared to non-transgenic rats (P < 0.05) without significant changes for the vehicle groups throughout the study (P > 0.05). NG-Nitro-L-arginine-methyl ester increased blood pressure, left ventricular weight and left ventricular weight indexed for body weight by +41%, +17.6% and +18.6% (P < 0.05) in transgenic and +25%, +5.3% and +6.7% (P > 0.05) in non-transgenic rats compared to untreated animals, respectively. Cardiac gene expression showed no differences between groups (P > 0.05).

Conclusion

Increased plasma angiotensinogen levels may sensitize to additional blood pressure stressors. Our preliminary results point towards an independent role of angiotensinogen in the pathogenesis of human hypertension and associated end-organ damage.