胰岛素抵抗血压大鼠血管舒张功能异常的机制

目的 探讨胰岛素抵抗高血压（ＩＲＨ）大鼠血管舒张功能的改变及其可能机制。方法 采用离体血管功能实验方法,在鼠主动脉的舒张功能有其平滑肌钙代谢功能;应用逆转 录多聚酶链反应技术检测主动脉平滑肌Ｃａ＾２＋－ＡＴＰ酶ｍＲＮＡ的表达水平,结果 （１）ＩＲＨ大鼠主动脉舒张速度减慢;（２）用无钙ｋｒｅｂｓ液灌流后苯肾上腺素引起的收缩反应显著低于对照大鼠;（３）ＩＲＨ大鼠主动脉平滑肌Ｃａ＾２＋－ＡＴＰ酶ｍＲＡＮ     

体外循环术中心肌缺血—再灌注损伤后肌浆网Cal^2＋调 …

目的研究体外循环术中心肌缺血－再灌注（Ｉ－Ｒ）损伤后肌浆网Ｃａ＾２＋调节蛋白ｍＲＮＡ表达。方法实验用犬１２只,主动脉阻断缺血６０ｍｉｎ、继之开放后再灌注６０ｍｉｎ,建立体外循环术中全心缺血－再灌注心肌损伤模型。于主动脉阻断期间,分组以冷晶体液停跳液间断灌注（ＩＣＣＣ）或温血停跳液持续灌注（ＣＷＢＣ）做心肌保护。采用ＲＴ－ＰＣＲ技术,测定ＳＲ Ｃａ＾２＋－ＡＴＰ酶、钙螯合蛋白的ｍＲＮＡ水平,观察心输     

卒中易感型自发性高血压大鼠血管平滑肌收缩装置对Ca2＋敏感性变化的研究

目的比较卒中易感型自发性高血压大鼠（ＳＨＲｓｐ）与常压（Ｗｉｓｔａｒ）大鼠基底动脉（ＢＡ）和尾动脉（ＣＡ）平滑肌收缩装置对Ｃａ２＋敏感性（以ｐＣａ５０表示）的差异。方法采用血管平滑肌细胞（ＶＳＭＣ）膜化学高通透技术并结合细胞钙钳制技术，使上述血管肌条（环）平滑肌细胞膜具有高通透性，并使胞内Ｃａ２＋固定于一定水平，然后制作神经鞘氨醇（ｓｐｈｉｎｇｏｓｉｎｅ）预温浴后的肌条（环）ｐＣａ－张力曲线，比较ＳＨＲｓｐ和Ｗｉｓｔａｒ大鼠ＢＡ和ＣＡ平滑肌在不同处理时的ｐＣａ５０值。结果不论ＳＨＲｓｐ或Ｗｉｓ－ｔａｒ大鼠，ＢＡ平滑肌收缩装置对Ｃａ２＋的敏感性均高于ＣＡ（Ｐ＜０．００５）。ＳＨＰｓｐ的ＢＡ和ＣＡ平滑肌收缩装置对Ｃａ２＋的敏感性均高于Ｗｉｓｔａｒ大鼠的相应血管（Ｐ＜０．００５）。蛋白激酶Ｃ（ＰＫＣ）抑制剂Ｓｐｈｉｎｇｏｓｉｎｅ可使ＳＨＲｓｐＣＡ平滑肌ｐＣａ－张力曲线右移，但不能使ＳＨＲｓｐＣＡ平滑肌ｐＣａ－张力曲线右移，甚至轻微左移。结论ＳＨＲｓｐＢＡ和ＣＡ平滑肌收缩装置对Ｃａ２＋的敏感性均高于Ｗｉｓｔａｒ大鼠，ＰＫＣ在这种Ｃａ２＋敏感性变化中所起的作用在ＢＡ和ＣＡ可能不同     

慢性胃炎脾胃虚实证红细胞游离Ca~(2 )及膜Ca~(2 )-Mg~(2 )-AT Pase研究

目的：从细胞和细胞膜酶分子水平探讨慢性胃炎中医脾胃虚实证病理生理特征。方法：测定１０２ 例慢性胃炎患者和３０ 例正常人红细胞［Ｃａ２＋ ］ｉ、ＡＴＰ含量、膜Ｃａ２＋ －Ｍｇ２＋ －ＡＴＰａｓｅ活性和２４ ｈ 尿１７－羟皮质类固醇排出量。结果：湿热证细胞内外Ｃａ２＋ 转换率加快,膜Ｃａ２＋ －Ｍｇ２＋ －ＡＴＰａｓｅ活性和细胞内ＡＴＰ合成量呈代偿性亢进;脾胃气虚Ｃａ２＋ 转换率有所下降,膜Ｃａ２＋ －Ｍｇ２＋ －ＡＴＰａｓｅ活性明显低于湿热,组织细胞代谢的代偿功能有所降低;脾肾气虚组织细胞代谢功能已完全失代偿,Ｃａ２＋ 在细胞内有明显滞留现象。结论：上述变化与肾上腺皮质功能有密切关系。     

原发性高血压患者红细胞内CA^2＋,Mg^2＋水平及细胞膜ATP酶活性

对正常人及原发性高血压患者细胞内、外Ｃａ２＋、Ｍｇ２＋浓度和细胞膜ＡＴＰ酶活性之间的关系进行评价。方法检测３２名正常人（ＮＴ），５５例原发性高血压病（ＨＴ）患者血浆和细胞内Ｃａ２＋、Ｍｇ２＋浓度（原子吸收法），细胞膜ＡＴＰ酶活性（比色法）。结果ＨＴ组血浆Ｃａ２＋浓度明显低于ＮＴ组，红细胞内Ｃａ２＋浓度明显高于ＮＴ组，红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶及Ｃａ２＋－ＡＴＰ酶活性明显低于ＮＴ组。血浆Ｍｇ２＋和红细胞内Ｍｇ２＋浓度与ＮＴ组无明显差别。结论原发性高血压患者细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶和Ｃａ２＋－ＡＴＰ酶活性明显减低，血浆Ｃａ２＋水平明显减低，红细胞内Ｃａ２＋超载。反映膜缺陷和离子运输系统失常与原发性高血压发病有关。而细胞内、外Ｍｇ２＋水平变化与高血压之间的关系须进一步研究。     

舒林酸对实验性高钙尿症的防治作用

目的 观察新型非类固醇类抗炎药－舒林酸对实验性高钙尿症的防治作用,探讨其可能机制。方法 建立大鼠实验性高钙尿症模型,观察舒林酸治疗后２周和４周尿Ｇａ、尿Ｃａ／Ｃｒ、尿ＮＡＧ／Ｃｒ以及肾和十二指肠Ｃａ＾２＋ＡＴＰ酶（钙泵）的变化。结果 ２周和４周时尿Ｃａ、尿Ｃａ／Ｃｒ、尿ＮＡＧ／Ｃｒ及肾和十二指肠Ｃａ＾２＋ＡＴＰ酶均显著下降（Ｐ〈０．０１）,２４ｈ尿钙定量与尿ＡＮＧ／Ｃｒ值呈正相关（Ｐ〈０．０１）。     

体外循环术中心肌缺血-再灌注损伤后肌浆网Ca2+调节蛋白mRNA表达

目的 研究体外循环术中心肌缺血－再灌注（Ｉ－Ｒ）损伤后肌浆网Ｃａ２＋调节蛋白ｍＲＮＡ表达。方法 实验用犬１２只,主动脉阻断缺血６０ｍｉｎ、继之开放后再灌注６０ｍｉｎ,建立体外循环术中全心缺血－再灌注心肌损伤模型。于主动脉阻断期间,分组以冷晶体液停跳液间断灌注（ＩＣＣＣ）或温血停跳液持续灌注（ＣＷＢＣ）做心肌保护。采用ＲＴＰＣＲ技术,测定 ＳＲ Ｃａ２＋－ＡＴＰ酶、钙螯合蛋白的ｍＲＮＡ水平,观察心输出量（ＣＯ）／左室收缩末期压（ＬＶＥＳＰ）两项心功能指标和心肌细胞超微结构的变化。结果 与缺血前比较,再灌注６０ｍｉｎ后：①ＩＣＣＣ组两种蛋白ｍＲＮＡ均显著上升（Ｐ＜０．０１）,ＣＷＢＣ组无显著变化（Ｐ＞０．０５）;②两组ＣＯ／ ＬＶＥＳＰ均显著下降（Ｐ＜０．０１）,但组间比较,ＩＣＣＣ组下降更为明显（Ｐ＜０．０１）;③ＩＣＣＣ组心肌细胞出现超微结构破坏性改变,ＣＷＢＣ组超微结构保持良好。结论 体外循环术中心肌Ｉ－Ｒ损伤后早期,心肌细胞肌浆网Ｃａ２＋调节蛋白发生了损伤后的分子修复;这种修复可能与心肌损伤程度呈相关。     

胆固醇、甘油三酯、高密度脂蛋白与红细胞膜离子酶活性关系研究

目的探讨高血压时血浆胆固醇（Ｃｈｏ）、甘油三酯（ＴＧ）和高密度脂蛋白（ＨＤＬ－Ｃ）水平与细胞膜离子运输酶活性之间的关系。方法３２名正常人（ＮＴ）,５５例原发性高血压（ＨＴ）患者,检测血浆Ｃｈｏ、ＴＧ、ＨＤＬ－Ｃ水平,红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶和Ｃａ２＋－ＡＴＰ酶活性,膜Ｃ／Ｐ克分子比率及膜内面Ｃａ２＋结合力。结果（１）ＨＴ组平均动脉血压（ＭＡＰ）与ＮＴ组相比有显著性差别;（２）ＨＴ组血浆ＨＤＬ－Ｃ水平、红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶和Ｃａ２＋－ＡＴＰ酶活性,以及膜内面Ｃａ２＋结合力均较ＮＴ组明显减低;（３）ＨＴ组血浆Ｃｈｏ,ＴＧ水平、红细胞膜Ｃｈｏ含量和Ｃ／Ｐ克分子比率,与ＮＴ组比较皆明显增高。结论红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶和Ｃａ２＋－ＡＴＰ酶活性减低,以及膜内面Ｃａ２＋结合力减低,是高血压时细胞膜离子运输失常的主要标志,血浆ＴＧ水平升高和膜磷脂水平减低可能是高血压时细胞膜理化特性及离子运输失常的主要决定因素。     

慢性肾功能衰竭患者红细胞变形能力与红细胞ATP酶活性及离子浓度关系的研究

检测６５例ＣＲＦ患者ＥＤ和红细胞ＡＴＰ酶活性及离子浓度的变化。结果显示：ＣＲＦ患者红细胞滤过指数（ＩＦ）和Ｃａ２＋，Ｎａ＋明显高于对照组（Ｐ＜０．００１），而Ｎａ＋－Ｋ＋－ＡＴＰ酶、Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶活性和Ｋ＋，Ｍｇ２＋明显低于对照组（Ｐ＜０．００１）。ＣＲＦ患者ＩＦ与Ｎａ＋－Ｋ＋－ＡＴＰ酶、Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶活性和Ｋ＋、Ｍｇ２＋浓度呈负相关，与Ｃａ２＋、Ｎａ＋浓度呈正相关。提示ＣＲＦ患者ＥＤ降低与红细胞ＡＴＰ酶活性降低和离子浓度异常有关。     

槲皮素对家兔主动脉血管平滑肌细胞胞内游离钙浓度的影响

目的：探讨槲皮素（Ｑｕｅ）对智力这平滑肌细胞胞内游离钙浓度（〖Ｃａ＾２＋）〗ｉ的影响。方法：采用新一代钙荧光探剂Ｆｌｕｏ－３／ＡＭ检测Ｑｕｅ对培养的兔主动脉血管平滑肌细胞（ＡＳＭＣ）〖Ｃａ＾２＋〗ｉ在高Ｋ＾＋、去甲肾上腺素（ＮＥ）、血管紧张素Ⅱ（ＡｎｇⅡ）刺作用下的改变,并与Ｖｅｒａｐａｍｉｌ进行对照研究。结果：Ｑｕｅ（１０＾－６、１０＾－４ｍｏｌ／ｌ）呈剂量依赖性抑制高Ｋ＾＋去极化引起的〖Ｃａ＾     

Reduction of large-conductance Ca²(+) -activated K(+) channel with compensatory increase of nitric oxide in insulin resistant rats

Cardiovascular disease prevalence and mortality are both increased by insulin resistance, hypertension, and atherosclerosis. The large-conductance Ca(2+)-activated K(+) channel (BK(Ca)) plays a pivotal role in the diastolic function of vascular smooth muscle cells. However, the role of this channel in insulin resistance remains unknown. Male Sprague-Dawley rats were randomly divided into an insulin resistant group and control group. We investigated the BK(Ca) current and subunit expression in myocytes from aortas and mesenteric arteries by Western blot, real-time PCR and the whole-cell patch-clamp methods. BK(Ca) current was decreased in smooth muscle cells in insulin resistant rats, compared with that in control group. Peak BK(Ca) current at + 60 mV was significantly decreased after iberiotoxin (IBTX) perfusion at 100 nmol/L (64.2 ± 4.7 versus 20.3 ± 3.5% in thoracic aortas and 65.6 ± 6.2 versus 29.3 ± 3.9% in mesenteric arteries, both p < 0.01). However, there was no significant difference in BK(Ca) alpha subunit between the two groups, both at the level of mRNA and protein. BK(Ca) beta 1 subunit expression in aortas and mesenteric arteries from the insulin resistant group was lower than in those from control group. The plasma level of nitric oxide was higher in the insulin resistant group than in the control group. Our results demonstrated that the BK(Ca) channel is decreased both in macrovessels and microvessels in insulin resistant rats. These impairments may be related to the down-regulation of β1 subunit expression and compensatory increase in plasma nitric oxide levels.     

Diminished expression of sarcoplasmic reticulum Ca(2+)-ATPase and ryanodine sensitive Ca(2+)Channel mRNA in streptozotocin-induced diabetic rat heart

The diabetic heart has an abnormal intracellular calcium ([Ca(2+)]i) metabolism. However, the responsible molecular mechanisms are unclear. The present study aimed to investigate mRNAs expressed in the proteins which regulate heart [Ca(2+)]i metabolism in streptozotocin (STZ)-induced diabetic rats. Expression of sarcoplasmic reticulum Ca(2+)-adenosine triphosphatase (SR Ca(2+)-ATPase) mRNA was significantly less in the heart 3 weeks after STZ injection than that in the age-matched controls. Together with the down-regulation of SR Ca(2+)-ATPase, expression of ryanodine sensitive Ca(2+)channel (RYR) mRNA was also decreased 12 weeks after STZ injection. Insulin supplementation fully restored the decreased mRNAs expression of SR Ca(2+)-ATPase and RYR. The diminished expression and restoration with insulin supplementation of SR Ca(2+)-ATPase was further confirmed at the protein level. In contrast, expression of mRNAs coding the L-type Ca(2+)channel, Na(+)-Ca(2+)exchanger, or phospholamban were not affected 3 or 12 weeks after STZ injection. These results can be taken to indicate that the down-regulation of SR Ca(2+)-ATPase and RYR mRNAs is a possible underlying cause of cardiac dysfunction in STZ-induced diabetic rats.     

Impaired SERCA function contributes to cardiomyocyte dysfunction in insulin resistant rats

Ventricular dysfunction in type 2 diabetic patients is becoming apparent early after diagnosis of diabetes, but the cellular mechanisms contributing to this dysfunction are not well established. Our group has recently identified cardiomyocyte dysfunction in diet-induced insulin resistant rats that have not developed type 2 diabetes. The present investigation was designed to determine cellular mechanisms contributing to slowed cardiomyocyte relaxation in sucrose (SU)-fed rats. SU-feeding was used to induce whole-body insulin resistance. After 9-12 weeks on diet, isolated ventricular myocyte shortening/relengthening were slower in SU-fed adult male Wistar rats (42-63%) compared to starch (ST)-fed controls. Cytosolic Ca2+ removal attributable to Na+/Ca2+ exchange (NCX) and to sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) was evaluated with fluo-3/AM. Caffeine-releasable Ca2+ and cytosolic Ca2+ clearing through NCX were normal, whereas Ca2+ uptake by SERCA was significantly slower in SU myocytes (330+/-29 ms) compared to ST cells (253+/-16 ms). Protein levels for SERCA, NCX and phospholamban were not affected by SU-feeding. Manipulating intracellular Ca2+ with various positive inotropic interventions (e.g. post-rest potentiation, isoproterenol) and changes in stimulus frequency demonstrated that mechanical properties can be improved in subsets of myocytes. Thus, we conclude that impaired SERCA activity (with normal protein content) contributes to cardiomyocyte dysfunction in insulin resistant animals, whereas NCX function and expression are normal. These results suggest that subtle changes in Ca2+ regulation which occur prior to overt ventricular dysfunction/failure, may be common to early stages of a number of disorders involving insulin resistance (e.g. diabetes, obesity, syndrome X and hypertension).     

The aetiology of essential hypertension.

Essential hypertension is primarily hereditary. The property inherited is present in all cells but because of adaptation and differentiation it is particularly prominent in systemic vascular smooth muscle. This inherited property is manifested functionally as increased reactivity to vasoactive substances, such as (-)noradrenaline and angiotensin II. This abnormal function is present before the onset of hypertension. Vascular hypertrophy and hyperplasia are not only caused by hyperactivity of the smooth muscle and by the hypertension itself but are also trophic effect of the agonists, especially noradrenaline. The only two proteins in vascular smooth muscle which can produce both contractile and trophic effects are the guanosine triphosphate binding protein (Gs) and phospholipase C. Phospholipase C has already been demonstrated to be abnormally active in response to agonists in the spontaneously hypertensive rat and in human essential hypertension. The Gs protein is less likely to be critically abnormal since it is active in the vascular smooth muscle relaxation cascade as well as in contraction. None of the other proteins involved in vascular smooth muscle contraction or relaxation affect both contractile reactivity and cellular growth. There are many secondary effects dependent upon the phospholipase C abnormality such as calcium (Ca2+) cellular content, Ca2+ Mg2+ ATPase pump effects and possibly Ca2+ Na+ exchange. There are also many secondary effects impinging on the phospholipase C abnormality including changes in noradrenaline and angiotensin II metabolism. Present antihypertensive therapy is directed largely at secondary factors dependent upon or influencing the primary phospholipase C cascade. The path is now open for a more direct and basic diagnostic and therapeutic attack.     

Adenoviral gene transfer of SERCA2a improves left-ventricular function in aortic-banded rats in transition to heart failure

In human and experimental models of heart failure, sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a) activity is decreased, resulting in abnormal calcium handling. The disturbances in calcium metabolism have been shown to contribute significantly to the contractile dysfunction observed in heart failure. We investigated whether increasing SERCA2a expression can improve ventricular function in an animal model of heart failure obtained by creating ascending aortic constriction in rats. After 19-23 wk of banding during the transition from compensated hypertrophy to heart failure (documented by >25% decrease in fractional shortening), rats were randomized to receive either an adenovirus carrying the SERCA2a gene (Ad.SERCA2a, n = 13) or beta-galactosidase (Ad.betagal, n = 14) by using a catheter-based technique. The failing hearts infected with Ad. betagal were characterized by a significant decrease in SERCA2a expression and a decrease in SERCA2a activity compared with nonfailing sham-operated rats (n = 11). In addition, these failing hearts had reduced left-ventricular systolic pressure, maximal rate of left-ventricular pressure rise and decline (+dP/dt, -dP/dt), and rate of isovolumic relaxation (tau). Overexpression of SERCA2a restored both SERCA2a expression and ATPase activity to nonfailing levels. Furthermore, rats infected with Ad.SERCA2a had significant improvement in left-ventricular systolic pressure, +dP/dt, -dP/dt, and rate of isovolumic relaxation (tau) normalizing them back to levels comparable to sham-operated rats. In this study, we show that in an animal model of heart failure where SERCA2a protein levels and activity are decreased and severe contractile dysfunction is present, overexpression of SERCA2a in vivo restores both systolic and diastolic function to normal levels.     

Effect of cerivastatin on endothelial dysfunction and aortic CD36 expression in diabetic hyperlipidemic rats.

A mutation of the CD36 gene that encodes a fatty acid transporter has been reported to play a role in insulin resistance in spontaneously hypertensive rat (SHR). Statins reduce circulating cholesterol and triglyceride concentrations. The objective of this study was to determine the role of CD36 and the significance of statin therapy in insulin-resistance syndromes. We determined the isometric relaxation induced by acetylcholine or lecithinized superoxide dismutase (SOD) in aortas obtained from Otsuka Long Evans Tokushima Fatty (OLETF) rats, a model of insulin resistance and dyslipidemia, and normal control (Long Evans Tokushima Otsuka; LETO) rats with or without cerivastatin treatment. We also determined the effect of cerivastatin on aortic expression of CD36 and PPARgamma. The CD36 genotype and microsatellite markers on chromosome 4 were also determined. The relaxation induced by acetylcholine and lecithinized SOD were attenuated in OLETF rats but restored by a low dose of cerivastatin without significant changes in serum cholesterol. These relaxations were also restored by a high dose of cerivastatin with significant reductions in serum cholesterol and triglyceride. Cerivastatin increased the aortic expression of CD36 and PPARgamma mRNA in both LETO and OLETF rats. However, the basal level of CD36 mRNA and the increase in CD36 mRNA in response to cerivastatin were significantly lower in OLETF rats than in LETO rats. Although the abnormal CD36 genotype reported in SHR was not found in OLETF rats, the microsatellite markers of D4Rat151 and D4Rat115 differed between OLETF and LETO rats. In conclusion, insulin resistance in OLETF rats may be partially due to an altered expression of CD36. Increased aortic expression of CD36 in response to cerivastatin could explain the reduction in serum triglyceride concentrations with statin therapy and may have pronounced beneficial effects in insulin-resistance syndromes.     

Expression of cardiac calcium regulatory proteins in atrium v ventricle in different species.

The duration of contraction in isolated electrically driven preparations from atrium and ventricle of mouse, rat, rabbit, guinea-pig and dog was consistently shorter in atrial compared to ventricular preparations. Overexpression of phospholamban (PLB) in transgenic mice prolonged duration of contraction, underscoring the importance of PLB for kinetics of cardiac contractility. The expression of regulatory proteins was studied by Western and Northern blot analysis. In rat myocardium, expression of the sarcoplasmic reticulum Ca2+ ATPase (SERCA) was higher in atrium than in ventricle, as was also observed in the rabbit, guinea-pig and wild-type mouse samples. Canine myocardium, however, had similar levels of SERCA (protein and mRNA) in atrium and ventricle. PLB and calsequestrin on protein and RNA levels were lower in atrium than in ventricle from rat, rabbit, guinea-pig and wild-type mouse. PLB protein and RNA levels were higher in ventricle than in atrium at ages 1 and 5 days postnatally and in adult rats. SERCA protein and RNA levels were higher in ventricle than in atrium at days 1 and 5 after birth, but lower in ventricle than in atrium in adult rats. In dog, the calsequestrin level was identical in atrium and ventricle (protein and mRNA) and PLB did not differ between atrium vs ventricle at the protein level but was lower at the mRNA level. Also, Ca2+ uptake was higher in atrium than in ventricle in the dog samples. The expression of the inhibitory subunit of troponin was unchanged between atrium and ventricle in all species studied (protein and mRNA). In dog, protein expression of triadin and junctin was lower in atrium vs ventricle. Triadin mRNA was not altered in dog atrium vs ventricle. In summary, while the hastened relaxation of atrium vs ventricle correlates in part with the lower expression of PLB and higher expression of SERCA, altered regional expression of other SR proteins handling Ca2+ may also play an important role in some species.     

Function of the sarcoplasmic reticulum and expression of its Ca2(+)-ATPase gene in pressure overload-induced cardiac hypertrophy in the rat

The reduction in Ca2+ concentration during diastole and relaxation occurs differently in normal hearts and in hypertrophied hearts secondary to pressure overload. We have studied some possible molecular mechanisms underlying these differences by examining the function of the sarcoplasmic reticulum and the expression of the gene encoding its Ca2(+)-ATPase in rat hearts with mild and severe compensatory hypertrophy induced by abdominal aortic constriction. Twelve sham-operated rats and 31 operated rats were studied 1 month after surgery. Eighteen animals exhibited mild hypertrophy (left ventricular wt/body wt less than 2.6) and 13 animals severe hypertrophy (left ventricular wt/body wt greater than 2.6). During hypertrophy we observed a decline in the function of the sarcoplasmic reticulum as assessed by the oxalate-stimulated Ca2+ uptake of homogenates of the left ventricle. Values decreased from 12.1 +/- 1.2 nmol Ca2+/mg protein/min in sham-operated rats to 9.1 +/- 1.5 and 6.7 +/- 1.1 in rats with mild and severe hypertrophy, respectively (p less than 0.001 and p less than 0.001, respectively, vs. shams). This decrease was accompanied by a parallel reduction in the number of functionally active CA2(+)-ATPase molecules, as determined by the level of Ca2(+)-dependent phosphorylated intermediate: 58.8 +/- 7.4 and 48.1 +/- 13.5 pmol P/mg protein in mild and severe hypertrophy, respectively, compared with 69.7 +/- 8.2 in shams (p less than 0.05 and p less than 0.01, respectively, vs. shams). Using S1 nuclease mapping, we observed that the Ca2(+)-ATPase messenger RNA (mRNA) from sham-operated and hypertrophied hearts was identical. Finally, the relative level of expression of the Ca2(+)-ATPase gene was studied by dot blot analysis at both the mRNA and protein levels using complementary DNA clones and a monoclonal antibody specific to the sarcoplasmic reticulum Ca2(+)-ATPase. In mild hypertrophy, the concentrations of Ca2(+)-ATPase mRNA and protein in the left ventricle were unchanged when compared with shams (mRNA, 93.8 +/- 10.6% vs. sham, NS; protein, 105.5 +/- 14% vs. sham, NS). in severe hypertrophy, the concentration of Ca2(+)-ATPase mRNA decreased to 68.7 +/- 12.9% and that of protein to 80.1 +/- 15.5% (p less than 0.001 and p less than 0.05, respectively), whereas the total amount of mRNA and enzyme per left ventricle was either unchanged or slightly increased. The slow velocity of relaxation of severely hypertrophied heart can be at least partially explained by the absence of an increase in the expression of the Ca2(+)-ATPase gene and by the relative diminution in the density of the Ca2+ pumps.(ABSTRACT TRUNCATED AT 400 WORDS)     

高血压左室肥厚与细胞离子转运和环核苷酸的关系

目的：探讨血流动力学、细胞阳离子转动和环核苷酸在高血压左心室肥厚（LVH）发生中的作用。方法：采用30例正常人和45例高血压非LVH病人双重同期对照,观察45例高血压LVH病人的血压、外周阻力,淋巴细胞ATP酶活性,阳离子和环核苷酸变化。结果：高血压LVH和非LVH病人血压、外周阻力、细胞离子转运和环核苷酸均有异常;高血压LVH组收缩压、细胞Na^ a^、Ca^ 、cAMP和cAMP/cGMP比值高于非LVH组,细胞Na^ ,K^ -三磷酸腺苷酶（Na^ －K^ －ATPase)、Ca^ －ATPase活性和K^ 低于非LVH组。左室重量指数（LVMI）与Ca^ －ATPase、Na^ 、cAMP和cAMP/cGMP比值相关。逐步回归分析显示,在16个相关预选因子中,Na^ 、Ca^ －ATPase、Mg^ ,cAMP与LVMI之间有独立的相关关系。结论：血流动力学、细胞阳离子转运和环核苷酸变化参与高血压LVH的发病过程,其中Na^ 、Ca^ －ATPase、Mg^ 和cAMP可能起重要作用。     

In vivo proliferation of rat vascular smooth muscle in relation to diabetes mellitus insulin-like growth factor I and insulin

Summary The roles of diabetes mellitus, insulin-like growth factor I and insulin in vascular smooth muscle proliferation in vivo were studied. Proliferation was induced by endothelial injury (balloon catheterization) of rat aorta, and was measured as ³H-thymidine incorporation into DNA. Levels of insulin-like growth factor I mRNA and insulin-like growth factor I receptor mRNA were measured with a solution hybridization assay. The increase in DNA synthesis was most pronounced 2 days after injury in both normal and diabetic rats and declined thereafter, but DNA synthesis in aortas from diabetic rats was lower throughout the time period studied. Levels of insulin-like growth factor I mRNA and the receptor mRNA were both increased in balloon catheterized aortas, and time-course studies showed an increase in receptor mRNA prior to the increase in insulin-like growth factor I mRNA. Diabetic rats were treated with equimolar concentrations of insulin (35 nmol/day) or insulin-like growth factor I (31 nmol/day) for 5 days. Insulin-like growth factor I increased DNA synthesis in injured aortas 2 days after injury without improving blood glucose, whereas the effect of insulin was associated with a decrease in blood glucose levels. In conclusion, vascular smooth muscle proliferation is impaired by diabetes and stimulated by insulin treatment. Insulin-like growth factor I infusion stimulates vascular smooth muscle proliferation without affecting bloo glucose, and gene expressions of insulin-like growth factor I and its receptor are increased in proliferating vascular smooth muscle, indicating that insulin-like growth factor I is involved in vascular smooth muscle proliferation in vivo.