卡维地洛减弱肥厚心肌能量代谢向胚胎型转换的分子机制

目的 :观察压力负荷性大鼠肥厚心肌能量代谢的转换模式及卡维地洛的作用 ,探讨卡维地洛减弱压力负荷性心肌能量代谢胚胎型转换的分子调控机制。方法 :用卡维地洛治疗腹主动脉缩窄术后 4周的雄性 Waster大鼠 ,治疗 12周后观察假手术组、腹主动脉缩窄组和卡维地洛干预组大鼠血流动力学参数、心室重构指标、血清和心肌游离脂肪酸的含量及肌型肉毒碱棕榈酰转移酶 I（ M-CPT-I）和中链脂酰辅酶 A脱氢酶 （ MCAD） m RNA的表达变化。结果 :术后 16周大鼠左室心肌明显肥厚 ,血清和心肌游离脂肪酸的含量增加 ,左室肥厚心肌 M-CPT-I和MCAD m RNA的表达下调。卡维地洛治疗 12周后能够明显改善上述变化。结论 :压力负荷性大鼠肥厚心肌能量代谢模式发生胚胎型转换 ;卡维地洛能够减少左室心肌脂肪酸氧化限速酶和关键酶的基因表达 ,减弱心肌胚胎型能量代谢的转换     

压力超负荷对大鼠心肌PPARα和MCAD mRNA表达的影响

目的 :了解压力负荷性肥厚心肌过氧化物酶体活化受体α(PPARα)和中链脂酰基辅酶A脱氢酶(MCAD)mRNA的表达变化 ,探讨PPARα对肥厚心肌脂肪酸 β氧化关键酶基因表达的调控作用及肥厚心肌能量底物的变化。方法 :观察大鼠腹主动脉缩窄术后 1、4、8、16周血流动力学参数、心室重塑指标、血清和心肌游离脂肪酸 (FFA)的含量及PPARα和MCADmRNA的表达变化。结果 :随着肥厚程度的增加 ,血清和心肌FFA蓄积增加 ,心肌PPARα和MCADmRNA的表达也逐渐下调 ,且与脂肪酸的利用下调相一致。结论 :肥厚心肌PPARα活性下调 ,与MCAD基因表达变化一致 ;PPARα在转录水平调控脂肪酸氧化酶基因的表达 ;PPARα与肥厚心肌能量底物转换密切相关     

压力负荷性大鼠肥厚心肌过氧化物酶体增殖剂活化受体α（PPARα）和肉碱棕榈酰转移酶（M—CPT—I）mRNA的表达变化

目的 了解压力负荷性肥厚心肌PPARα和M—CPT—ImRNA的表达变化，探讨PPARα调控心肌线粒体脂肪酸摄取及维持能量和脂质平衡的作用。方法 观察大鼠腹主动脉缩窄术后2、4、8、16周血流动力学参数、心室重塑指标、血清和心肌游离脂肪酸的含量及PPARα和M—CPT—ImRNA的表达变化。结果 随着肥厚程度的增加，压力负荷性大鼠血清和心肌游离脂肪酸蓄积增加，心肌PPARα和M—CPT—ImRNA的表达逐渐下调，而且与脂肪酸的利用下调相一致。结论 病理性肥厚心肌能量代谢底物发生改变，脂肪酸氧化不占主导地位；PPARα在转录水平上失活，对心肌线粒体脂肪酸摄取起重要的调控作用；PPARα可能与肥厚心肌能量和脂质失衡有关。     

大鼠左室肥厚心肌PPARα信号通路失活及其意义

目的 :观察压力超负荷左室肥厚心肌过氧化物酶体增殖剂活化受体α(PPARα)mRNA和蛋白的表达变化 ,探讨PPARα信号通路失活与左室肥厚心肌能量底物转换的关系。方法 :检测大鼠腹主动脉缩窄术后 2周、4周和 8周血流动力学参数、心室重塑指标、血清和心肌游离脂肪酸的含量及PPARαmRNA和蛋白的表达变化。结果 :术后 2周左室已出现肥厚 ,伴有PPARαmRNA表达下调 ;术后 8周PPARα蛋白水平开始下调 :随着肥厚程度的增加 ,血清和心肌游离脂肪酸蓄积增加 ,左室心肌PPARαmRNA和蛋白的表达进行性下调。结论 :病理性肥厚心肌PPARα活性下调与能量底物的利用变化相一致 ,预示PPARα信号通路是病理性心室重塑防治新策略的一个有效靶点     

探讨压力超负荷对大鼠左室心肌脂肪酸氧化的影响

目的 :观察腹主动脉缩窄术后大鼠左室心肌脂肪酸氧化限速酶M CPT I和关键酶MCAD基因表达的变化 ,探讨压力超负荷对心肌能量代谢的影响及机制。方法 :观察大鼠腹主动脉缩窄术后 2、4、8、16周血流动力学参数、心室重塑指标、血清和心肌游离脂肪酸的含量及M CPT I和MCADmRNA的表达变化。结果 :术后 4周左室出现明显肥厚。随着肥厚程度的增加 ,压力负荷性大鼠血清和心肌游离脂肪酸蓄积增加 ,左室心肌M CPT I和MCADmRNA的表达逐渐下调 ,而且与脂肪酸的利用下调相一致。结论 :压力超负荷能够下调脂肪酸氧化限速酶和关键酶的基因表达 ,影响心肌能量代谢底物的转换。说明肥厚心肌存在能量代谢障碍 ,机械信号能够影响心肌能量底物的转换     

压力负荷性大鼠肥厚心肌过氧化物酶体增殖剂活化受体α(PPARα)和肉碱棕榈酰转移酶(M-CPT-I) mRNA的表达变化

目的了解压力负荷性肥厚心肌PPAR α和M-CPT-I mRNA的表达变化,探讨PPARα调控心肌线粒体脂肪酸摄取及维持能量和脂质平衡的作用.方法观察大鼠腹主动脉缩窄术后2、4、8、16周血流动力学参数、心室重塑指标、血清和心肌游离脂肪酸的含量及PPAR α和M-CPT-I mRNA的表达变化.结果随着肥厚程度的增加,压力负荷性大鼠血清和心肌游离脂肪酸蓄积增加,心肌PPAR α和M-CPT-I mRNA的表达逐渐下调,而且与脂肪酸的利用下调相一致.结论病理性肥厚心肌能量代谢底物发生改变,脂肪酸氧化不占主导地位;PPAR α在转录水平上失活,对心肌线粒体脂肪酸摄取起重要的调控作用;PPAR α可能与肥厚心肌能量和脂质失衡有关.     

非诺贝特对慢性心力衰竭大鼠心肌能量代谢和心室重构的影响

目的研究非诺贝特对慢性心力衰竭(CHF)大鼠心肌能量代谢和心室重构的影响。方法健康雄性Wistar大鼠随机选为假手术组18只;采用腹主动脉缩窄术制备CHF、并成功存活的38只再随机分为对照组20只、非诺贝特组18只[非诺贝特150 mg/(kg·d)],干预10周。计算左心室心肌重构指数、胶原容积分数(CVF)、心肌线粒体损伤程度分级用Flameng评分,免疫印迹法测过氧化物酶体增殖物激活受体α(PPARα)、中链酰基辅酶A脱氢酶(MCAD)、肌型肉碱棕榈酰转移酶1(MCPT 1)蛋白表达,RT-PCR测PPARα、MCAD和MCPT-1mRNA表达。结果与假手术组比较,对照组及非诺贝特组左心室心肌重构指数、CVF和Flameng评分均升高(P<0.05);非诺贝特组左心室心肌重构指数高于对照组、CVF和Flameng评分低于对照组(P<0.05);与假手术组比较,对照组、非诺贝特组心肌PPARα、MCPT-1、MCAD蛋白和基因表达均下调(P<0.05);非诺贝特组表达较对照组上调(P<0.05)。结论非诺贝特通过增强脂肪酸氧化,减轻线粒体损伤,改善心室重构,减轻心肌纤维化。     

丹参酮Ⅱ A对左心室肥厚的逆转作用及其机制

目的 研究丹参酮Ⅱ A对大鼠腹主动脉缩窄术后左室肥厚心肌的作用及一氧化氮的影响.方法 SD大鼠行腹主动脉缩窄术建立高血压左室心肌肥厚模型,术后4周将手术大鼠随机分为假手术组、未治疗左室肥厚(LVH)组、丹参酮低剂量组[10 mg/(kg·d),腹腔注射]、丹参酮高剂量组[20 mg/(kg·d),腹腔注射]及缬沙坦组[10 mg/(kg·d),灌胃],每组各8只.用药8周后通过超声心动图测定左室后壁、室间隔的厚度;取左心室组织检测左心室质量指数(LVMI)、病理切片HE染色测量心肌纤维直径(MFD);硝酸还原法测定心肌组织NO的含量、免疫印迹法(Western blot)检测蛋白激酶C(PKC)蛋白的表达.结果 腹主动脉缩窄术后,SD大鼠血压明显升高,出现左心室肥厚.缬沙坦可降低大鼠的血压[(136±15)mm Hg]并减轻左心室肥厚.低剂量、高剂量丹参酮组与LVH组相比虽不能降低血压[(188±11)、(187±14)mm Hg vs(186±13)mm Hg,P＞0.05],但能明显减低左室后壁、室间隔厚度、LVMI、MFD值(P＜0.01),同时可使心肌的NO明显增加[(12.8±1.7)、(12.0±1.4)vs(5.8±1.1)μmol/g,P＜0.01],心肌PKC蛋白的表达明显下调[(0.605±0.051)、(0.519±0.062)vs(1.291±0.117),P＜0.01].结论 丹参酮对心肌肥厚的逆转作用是非血压依从性的,丹参酮Ⅱ A可能通过促进心肌局部NO的产生、抑制PKC蛋白的表达起到阻止、逆转高血压心肌肥厚的发展.     

丹参酮Ⅱ A对左心室肥厚的逆转作用及其机制

目的研究丹参酮ⅡA对大鼠腹主动脉缩窄术后左室肥厚心肌的作用及一氧化氮的影响。方法SD大鼠行腹主动脉缩窄术建立高血压左室心肌肥厚模型,术后4周将手术大鼠随机分为假手术组、未治疗左室肥厚(LVH)组、丹参酮低剂量组[10mg/(kg.d),腹腔注射]、丹参酮高剂量组[20mg/(kg.d),腹腔注射]及缬沙坦组[10mg/(kg.d),灌胃],每组各8只。用药8周后通过超声心动图测定左室后壁、室间隔的厚度;取左心室组织检测左心室质量指数(LVMI)、病理切片HE染色测量心肌纤维直径(MFD);硝酸还原法测定心肌组织NO的含量、免疫印迹法(Western blot)检测蛋白激酶C(PKC)蛋白的表达。结果腹主动脉缩窄术后,SD大鼠血压明显升高,出现左心室肥厚。缬沙坦可降低大鼠的血压[(136±15)mm Hg]并减轻左心室肥厚。低剂量、高剂量丹参酮组与LVH组相比虽不能降低血压[(188±11)、(187±14)mm Hg vs(186±13)mm Hg,P>0.05],但能明显减低左室后壁、室间隔厚度、LVMI、MFD值(P<0.01),同时可使心肌的NO明显增加[(12.8±1.7)、(12.0±1.4)vs(5.8±1.1)μmol/g,P<0.01],心肌PKC蛋白的表达明显下调[(0.605±0.051)、(0.519±0.062)vs(1.291±0.117),P<0.01]。结论丹参酮ⅡA对心肌肥厚的逆转作用是非血压依从性的,丹参酮Ⅱ A可能通过促进心肌局部NO的产生、抑制PKC蛋白的表达起到阻止、逆转高血压心肌肥厚的发展。     

潜阳合剂对腹主动脉缩窄致高血压左室肥厚的影响

目的研究中药复方潜阳合剂对腹主动脉缩窄致高血压左室肥厚的影响,并探讨其作用机制。方法使用腹主动脉缩窄致高血压左室肥厚模型,Wistar大鼠随机分成假手术组和模型组,将高血压造模成功的大鼠随机分成模型组、培哚普利组和潜阳合剂组,每组10只,并开始灌胃,各组药物干预8周。使用心脏超声评价左室肥厚水平,尾动脉仪测量大鼠左前肢血压,天狼猩红染色观察心肌胶原含量,免疫组化法测定心肌组织Ⅰ型、Ⅲ型胶原纤维的含量。结果腹主动脉缩窄后12周,与假手术组相比,模型组血压升高,左室后壁及室间隔厚度增厚(P<0.001),左室舒张末内径和收缩末内径缩小(P<0.001);与模型组相比,培哚普利组和潜阳合剂组血压降低,左室后壁和室间隔厚度降低(P<0.001),舒张末内径(P<0.001)和收缩末内径(P<0.05)改善;与模型组相比,培哚普利组、潜阳合剂组大鼠心肌组织胶原较少,Ⅰ型和Ⅲ型胶原纤维表达减少。结论潜阳合剂可以改善腹主动脉缩窄致高血压大鼠的左室肥厚,其机制与降压、抑制心肌胶原纤维增生相关。     

On the Role of the Septal Area in the Development of Doca-Salt Hypertension in the Rat

The extensive destruction of forebrain noradrenergic nerve terminals by the intraventricular injection of 250 μg of 6-hydroxy-dopamine prevents the subsequent development of DOCA-salt experimental hypertension in rats while the lesser destruction of noradrenergic nerve terminals produced by 90 μg of 6-hydroxydopa does not. The greatest difference in brain part noradrenaline levels between these two neurotoxins was in the septal area where noradrenaline was less than 15% of controls after 6-hydroxydopamine but was the same as controls after 6-hydroxydopa. The non-specific destruction of the lateral septal area by radiofrequency lesions prevented the subsequent development of DOCA-salt hypertension. The relatively selective destruction of catecholamine nerve terminals in the lateral septal area by the injection of 1 μg 6-hydroxydopamine in 1 μl vehicle also prevented the development of DOCA-salt hypertension. These data suggest that the lateral septal area may be the location of the forebrain catecholaminergic neural activity that is necessary for the development of DOCA-salt experimental hypertension in rats.     

Role of the placenta in the control of the ante-partum surge of prolactin in the rat

A nocturnal surge of prolactin secretion occurs in the dark period preceding parturition in the rat. The aim of this study was to examine the role of the placenta in the control of this prolactin surge. Plasma prolactin and progesterone were measured by radioimmunoassay in serial blood samples collected after surgical removal of conceptuses during late pregnancy, and after intracerebroventricular (i.c.v.) injection of placental lactogen (PL) before the prolactin surge. In intact control animals, prolactin secretion remained low until a nocturnal surge of secretion occurred in the dark period preceding parturition, peaking at 269 +/- 51 (S.E.M.) micrograms/l at 03.00 h on day 21. Progesterone levels fell from greater than 200 nmol/l on day 19 to less than 40 nmol/l by 12.00 h on day 20 of pregnancy. PL levels during late pregnancy were modified by partial or complete removal of conceptuses at 10.00 h on day 19 of pregnancy. Removal of all but one or two conceptuses did not change the normal pattern of prolactin or progesterone secretion. Removal of all conceptuses, however, induced a large nocturnal surge of prolactin secretion, peaking at 211.7 +/- 78 micrograms/l at 03.00 h on day 20, 24 h earlier than the surge in intact animals. Progesterone levels after removal of all conceptuses fell to less than 40 nmol/l by 23.00 h on day 19, approximately 12 h before the decline in intact animals. Maintenance of increased progesterone levels after conceptus removal using silicone tubing implants significantly (P less than 0.05) reduced the peak of the premature prolactin surge to 79.7 +/- 18 micrograms/l at 05.00 h on day 20.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of the manifestation of diabetes in the elderly in the presymptomatic stage

Diabetes Mellitus is thought as the presymptomatic stage to cause various vascular diseases. From the point of view that diabetes is already a disease, this paper discusses the prevention of the manifestation of diabetes in the elderly. STOP-NIDDM study demonstrated that acarbose, an alpha-glucosidase inhibitor, reduced the onset of diabetes in impaired glucose tolerance (IGT) subjects by 24%. On the other hand, the Diabetes Prevention Program (DPP) study for IGT subjects revealed that intensive life style intervention prevented diabetes most powerfully by 58% and metformin treatment also reduced by 31%. Furthermore, HOPE, LIFE, and SCOPE studies against hypertension showed that ACI or ARB reduced diabetes by 20-32%, and the WOSCOT study that pravastatin, a HMG-CoA reductase inhibitor, reduced diabetes by 30%. These accumulated results suggest that the most suitable strategy to prevent diabetes in the elderly is intensive life style intervention, and in cases incapable of exercise and diet therapy, acarbose or metformin are recommended for IGT. When associated with hypertension and/or hyperlipidemia, the subjects have to receive ACI or ARB and statins to prevent diabetes.     

Oxprenolol in the treatment of hypertension in the elderly

Controversy continues to surround the value of drug treatment of hypertension in the elderly. Epidemiologic evidence implicates hypertension as a major risk factor in the precocious development of stroke and coronary heart disease in the elderly subject as clearly as it is implicated in the younger person. The hemodynamic and neuroendocrine profiles of the older patient with essential hypertension are similar to those of younger patients in the stable phase of the disease. However, the arterial ravages induced by many years of sustained hypertension render the circulation of the elderly subject more sensitive to pharmacologic intervention. The benefit-risk ratio of most antihypertensive drugs appears to be inversely related to age. Diuretics reduce the blood pressure at rest but have no influence on the increases in systolic pressure during normal activity; in addition, they carry potentially serious metabolic hazards in the elderly hypertensive patient. Centrally acting drugs likewise lower the blood pressure at rest without influencing the high systolic pressures induced by exercise. They also enhance the tendency to endogenous depression. Adrenergic-neurone blocking drugs and alpha-adrenoceptor antagonists are contraindicated because of the frequency of impaired cardiovascular reflexes in the elderly. The beta-blocking drugs can reduce the risk of coronary and cerebrovascular disease in the older patient with hypertension. They appear to be well tolerated, but because of their impaired metabolic handling in many elderly patients they should probably be used in smaller doses than those prescribed in younger patients. The influence of antihypertensive treatment on cardiovascular morbidity and mortality in the elderly hypertensive patient is not known.     

Tissue Oxygen Demand in Regulation of the Behavior of the Cells in the Vasculature

The control of arteriolar diameters in microvasculature has been in the focus of studies on mechanisms matching oxygen demand and supply at the tissue level. Functionally, important vascular elements include EC, VSMC, and RBC. Integration of these different cell types into functional units aimed at matching tissue oxygen supply with tissue oxygen demand is only achieved when all these cells can respond to the signals of tissue oxygen demand. Many vasoactive agents that serve as signals of tissue oxygen demand have their receptors on all these types of cells (VSMC, EC, and RBC) implying that there can be a coordinated regulation of their behavior by the tissue oxygen demand. Such functions of RBC as oxygen carrying by Hb, rheology, and release of vasoactive agents are considered. Several common extra‐ and intracellular signaling pathways that link tissue oxygen demand with control of VSMC contractility, EC permeability, and RBC functioning are discussed.