高血压患者血浆和淋巴细胞中血管紧张素Ⅱ、内皮素和一氧化氮的变化及关系

分析一组高血压病患者血浆和淋巴细胞中血管紧张素Ⅱ（ＡｎｇⅡ）、内皮素（ＥＴ）和一氧化氮（ＮＯ）含量的变化及它们间的相互关系。方法高血压（ＥＨ）组３９例，正常对照（ＮＣ）组４１例，放射免疫分析法测定ＡｎｇⅡ、ＥＴ，高效液相色谱分析法测定ＮＯ。结果ＥＨ患者血浆和淋巴细胞中ＥＴ均高于ＮＣ组（Ｐ分别＜０．０５和＜０．０１），ＮＯ低于ＮＣ组（Ｐ分别＜０．０５和＜０．０１）。除血浆ＥＴ和ＮＯ外，各指标改变ＥＨⅡ期较Ⅰ期明显（Ｐ分别＜０．０５和＜０．０１）。逐步回归分析表明，ＥＨ组平均动脉压（ＭＡＰ）与血浆及淋巴细胞中ＡｎｇⅡ、ＥＴ呈正相关，与ＮＯ负相关（ｒ分别＝０．６７，０．８１，Ｐ均＜０．０１）；ＥＨ组血浆和淋巴细胞中ＮＯ与ＡｎｇⅡ、ＥＴ均呈负相关（ｒ分别＝－０．６５１，－０．７２５，Ｐ均＜０．０１）。结论淋巴细胞反映血管内皮细胞内分泌功能比血浆更为敏感，与ＭＡＰ相关性更好，ＡｎｇⅡ、ＥＴ和ＮＯ三者分泌失平衡，是ＥＨ发病的重要原因之一。     

充血性心衰患者血浆内皮素和一氧化氮变化的临床意义及培哚普利的干预作用

为了解充血性心衰（ＣＨＦ）时心钠素（ＡＮＦ），内皮素（ＥＴ）和一氧化氮（ＮＯ）变化的临床意义及培哚普利的于预作用，我们选择４０例临床确诊为ＣＨＦ的患者，并随机分为培哚普利治疗组和常规治疗组，放免法测定血浆ＡＮＦ，ＥＴ含量，比色法测定血浆ＮＯ含量，与正常对照组比较，并观察治疗前后上述指标的变化情况。结果ＣＨＦ患者的血浆ＡＮＦ，ＥＴ水平均显著高于对照组（Ｐ＜０．０１），ＮＯ明显低于对照组（Ｐ＜０．０５）。常规治疗组治疗前后上述指标无明显改变（Ｐ＞０．０５），培哚普利平均治疗８周后ＡＮＦ，ＥＴ显著下降（Ｐ＜０．００１）而ＮＯ显著上升（Ｐ＜０．０５），提示ＡＮＦ，ＥＴ和ＮＯ参与了ＣＨＦ的病理生理过程。培哚普利可以降低ＣＨＦ的治疗有益。     

冠心病原发性高血压患者血浆内皮素的研究

目的研究血浆内皮素（ＥＴ）与冠心病（ＣＨＤ）、原发性高血压（ＥＨ）的发生发展之间关系。方法我们用放免法测定了１３例ＣＨＤ患者（ＣＨＤ组）和１９例ＥＨ患者（ＥＨ组），观察ＥＴ浓度变化并与１８例健康人（对照组）进行比较。结果其中ＣＨＤ组及ＥＨ组血浆ＥＴ较对照组明显增高（Ｐ＜０．０５，Ｐ＜０．０１）；将ＥＨ组进行分期，与对照组比较，ＥＨ－Ｉ期无明显增高（Ｐ＞０．０５），ＥＨ－Ⅱ及ＥＨ－Ⅲ期均较对照组明显增高（Ｐ＜０．０１）。结论上述结果提示ＥＴ在ＣＨＤ及ＥＨ的发生与发展方面具有重要意义     

血管迷走性晕厥患者倾斜试验中血浆内皮素、内皮舒张因子和心率变异性的研究

目的通过研究血管迷走性晕厥患者倾斜试验中血浆内皮源性血管活性物质和心率变异性的变化来了解自主神经及血管内皮功能在血管迷走性晕厥发生机制中的作用。方法２５例患者，倾斜试验阳性１５例，阴性１０例，于倾斜试验前和倾斜不同时间测定血浆内皮素（ＥＴ）、一氧化氮（ＮＯ）水平，采用动态心电图监测心率变异性的变化。结果（１）倾斜试验阳性组出现阳性反应时血浆ＥＴ水平明显增高，高于倾斜前水平和倾斜试验阴性组（Ｐ＜０．０５和Ｐ＜０．０１）。（２）倾斜试验阳性组血浆ＮＯ水平在倾斜前、倾斜后１０分钟和出现阳性反应各阶段均明显低于倾斜试验阴性组（Ｐ＜０．０５和Ｐ＜０．０１）；两组血浆ＮＯ水平分别在试验阳性时和试验终止时均高于倾斜前水平（Ｐ＜０．０５和Ｐ＜０．０１）。（３）倾斜试验阳性者出现阳性反应时，心率变异指标ＬＦ有明显下降（Ｐ＜０．０５），ＨＦ也有下降。结论血管内皮功能的调节异常和自主神经功能异常可能共同参与了血管迷走性晕厥的发生机制，两者可能存在相互作用。     

冠心病心力衰竭患者血甲状腺激素的变化

目的：探讨甲状腺激素与冠心病心力衰竭的关系。方法：运用放射免疫法测定冠心病非心力衰竭患者（３２ 例）、冠心病心力衰竭患者（５６ 例）及健康者（４０ 例）血浆游离甲状腺素（ Ｆ Ｔ４）、游离三碘甲状腺原氨酸（ Ｆ Ｔ３ ）及促甲状腺素（ Ｔ Ｓ Ｈ）,分别用酶法及透射比浊法测定血浆总胆固醇（ Ｔ Ｃ）、高密度脂蛋白胆固醇（ Ｈ Ｄ Ｌ Ｃ）、低密度脂蛋白胆固醇（ Ｌ Ｄ Ｌ Ｃ）及载脂蛋白 Ａ Ｉ（ａｐｏ ＡⅠ）、载脂蛋白 Ｂ（ａｐｏ Ｂ）。结果：冠心病非心力衰竭组血浆 Ｔ Ｃ、 Ｌ Ｄ Ｌ Ｃ明显高于健康对照组（ Ｐ ＜ ０．０５）, Ｈ Ｄ Ｌ Ｃ 显著低于健康对照组（ Ｐ ＜ ０．０５）;冠心病心力衰竭组血浆 Ｔ Ｃ、 Ｌ Ｄ Ｌ Ｃ 及ａｐｏ Ｂ明显高于健康对照组（ Ｐ ＜ ０．０５～０．０１）;血浆 Ｈ Ｄ Ｌ Ｃ及 ａｐｏ ＡⅠ显著低于健康对照组（ Ｐ ＜ ０．０５）;血浆 Ｆ Ｔ３低于健康对照组及冠心病非心力衰竭组（ Ｐ ＜ ０．０５～０．０１）。冠心病患者及健康人各血脂成份与 Ｆ Ｔ３、 Ｆ Ｔ４ 及 Ｔ Ｓ Ｈ 均无明显相关性（ Ｐ ＞ ０．０５）。结论：冠心病心力衰竭患者体内 Ｆ Ｔ３ 降低, Ｔ３ 可能安全有效地用于治疗此类患者值得进一步研究。     

Ⅱ型糖尿病合并高血压患者氧化损伤及抗氧化酶活性的研究

目的：评价氧化损伤及抗氧化酶活性对型糖尿病（ Ｎ Ｉ Ｄ Ｄ Ｍ）及其伴发高血压（ Ｈ Ｔ）的影响。　方法与结果：采用鲁米诺依赖的中性粒细胞化学发光法,对１３６ 例 Ｎ Ｉ Ｄ Ｄ Ｍ 患者（其中 ７０ 例不伴有 Ｈ Ｔ,６６ 例伴有 Ｈ Ｔ）及３０ 例年龄匹配的健康对照者, 检测其外周血中性粒细胞产生氧自由基（ Ｏ Ｆ Ｒ）的水平。采用化学定量法,测定其血浆脂质过氧化终末产物－ 丙二醛（ Ｍ Ｄ Ａ）的浓度及抗氧化酶－ 超氧化物歧化酶（ Ｓ Ｏ Ｄ）、谷胱甘肽过氧化物酶（ Ｇ Ｓ Ｈ Ｐｘ）的活性。 Ｎ Ｉ Ｄ Ｄ Ｍ 伴发 Ｈ Ｔ组,其 Ｐ Ｍ Ｎ┐ Ｃ Ｌ 峰值、积分和吞噬指数均明显高于 Ｎ Ｉ Ｄ Ｄ Ｍ 不伴 Ｈ Ｔ组及健康对照组;血浆 Ｍ Ｄ Ａ浓度较后两组也明显升高（ Ｐ均＜ ０．０１）; Ｎ Ｉ Ｄ Ｄ Ｍ 组及 Ｎ Ｉ Ｄ Ｄ Ｍ 伴发 Ｈ Ｔ组的血浆 Ｓ Ｏ Ｄ和 Ｇ Ｓ Ｈ Ｐｘ 活性较正常对照组均明显降低（ Ｐ均＜ ０．０１）;但与 Ｎ Ｉ Ｄ Ｄ Ｍ 组相比, Ｎ Ｉ Ｄ Ｄ Ｍ 伴发 Ｈ Ｔ组的血浆 Ｓ Ｏ Ｄ 和 Ｇ Ｓ Ｈ Ｐｘ 活性其差异无显著性（ Ｐ均＞ ０．０５）; Ｐ Ｍ Ｎ┐ Ｃ Ｌ峰值与 Ｍ Ｄ Ａ呈明显正相关（ｒ＝ ０．７４８６, Ｙ＝ １５９．８ Ｘ＋ １３２．２, Ｐ＜ ０．０１,     

充血性心力衰竭病人血浆内皮素与肺动脉高压

用放免法测定了５４例充血性心力衰竭（ＣＨＦ）病人的血浆内皮素（ＥＴ）与漂浮导管血流动力学指标做相关回归分析。结果示ＣＨＦ组血浆ＥＴ较正常人增高约３倍，以血浆ＥＴ＞７ｐｇ／ｍｌ作为本组ＣＨＦ的预警指标，敏感性８５．２％、特异性８３．３％，血浆ＥＴ分别与肺循环阻力（ｒ＝０．７５）、平均肺动脉压（ｒ＝０．７４）、平均肺毛压（ｒ＝０．６３）和平均右房压（ｒ＝０．５４）呈显著正相关（Ｐ＜０．０１或０．０５），与心指数（ｒ＝－０．５６）和每搏指数（ｒ＝－０．７４）呈显著负相关，而与体循环阻力和平均动脉压相关不显著，心功能越差，血浆ＥＴ增高越明显。提示ＣＨＦ时存在ＥＴ产生和清除异常，增高的循环ＥＴ可能参与了ＣＨＦ的病理过程，尤其与肺动脉高压的发生、发展密切相关。     

乙型肝炎及原发性肝癌患者sIL-2R的变化

目的探讨ｓＩＬ２Ｒ水平与乙型肝炎病情的关系及其在原发性肝癌早期诊断中的价值．方法以ＥＬＩＳＡ法动态检测１１３例乙型肝炎及６例原发性肝癌患者ｓＩＬ２Ｒ水平，另选３１例健康体检者作对照组．结果以ｑ检验、ｔ检验进行统计学处理（微机处理，ＰＯＭＳ２００版）．结果各型乙型肝炎ｓＩＬ２Ｒ水平均显著高于正常对照（ＮＣ）组（Ｐ＜００１），其顺序依次为：ＨＣＣ＞ＣＳＨ＞ＣＨ（ＩＩ）＞ＬＣ＞ＣＨ（ＩＩ）＞ＡＨ＞ＣＨ（Ｉ）＞ＮＣ．ＨＣＣ组ｓＩＬ２Ｒ均值达正常值的２倍以上，且与ＣＨ（Ｉ），ＣＨ（Ｉ），ＡＨ间存在显著性差异（Ｐ＜００１，＜００５及＜００５）；ＣＨ（ＩＩ）组显著高于ＣＨ（Ｉ）组（Ｐ＜００１）．ＨＢｅＡｇ阳性组及ＨＢＶＤＮＡ阳性组ｓＩＬ２Ｒ水平显著高于阴性组．结论ｓＩＬ２Ｒ是监测乙型肝炎病情、ＨＢＶ复制及诊断早期原发性肝癌的一项敏感标志．     

结核性脑膜炎患者血清甲状腺激素水平的研究

本文采用放射免疫法检测３０例结核性脑膜炎患者血清甲状腺激素水平。结果表明：结脑患者血清ＴＴ４、ＴＴ３和Ｔ３ｒＴ３比值均较健康人为低（Ｐ＜０．０１），ｒＴ３和Ｔ３ＲＵ则增高（Ｐ＜０．０１），ＴＳＨ虽降低，但差异无显著性（Ｐ＞０．０５）ｍ，ＦＴ４Ｉ亦无显著性差异（Ｐ＞０．０５）。结果还提示，结脑患者甲状腺激素水平与病情有关。     

老年高血压病患者血浆内皮素与左室重量和功能关系的研究

目的探讨老年高血压病患者（ＥＨ）血浆内皮素（ＥＴ）与左室重量和功能的关系。方法采用放射免疫分析法和多普勒超声心动图技术检测８６例ＥＨ患者和５７例健康对照者血浆ＥＴ的浓度及室间隔（ＩＶＳＴ）、左室后壁厚度（ＰＷＴ）、左室心肌重量指数（ＬＶＭＩ）以及左室流入道Ｅ峰和Ａ峰比值（Ｅ／Ａ）、Ｅ峰加速面积（ＥＡＡ）。结果ＥＨ组ＥＴ、ＩＶＳＴ、ＰＷＴ、ＬＶＭＩ显著高于对照组（Ｐ值均＜０．０１）,Ｅ／Ａ、ＥＡＡ显著低于对照组（Ｐ＜０．０１）;ＥＨ组ＥＴ与ＩＶＳＴ、ＬＰＷＴ、ＬＶＭＩ之间均存在着显著正相关（Ｐ值均＜０．０１）,ＥＴ与Ｅ／Ａ、ＥＡＡ之间均存在着显著负相关（Ｐ值均＜０．０１）。结论ＥＴ可能是引起ＥＨ患者左室肥厚及舒张功能不全的原因之一。     

Autonomic neuropathy in diabetics--autonomic function and plasma catecholamines

Autonomic neuropathy is one of the complications of diabetes. Recently, several authors reported that measuring R-R interval variation of ECG is a noninvasive and useful method for testing parasympathetic function. However, there were few reports about sympathetic function in diabetics. In order to evaluate sympathetic function in diabetics quantitatively, we studied the responses of plasma norepinephrine (NE), epinephrine (E) and related factors after 60 min bed rest and sequentially during 10 min of upright posture and 5 min handgrip while still upright. We also studied the responses of NE and E during 5 min smoking in supine position. Subjects were divided into four age-matched groups. These were 15 normal subjects (Group I), 20 diabetics without complications (Group II), 20 diabetics with peripheral neuropathy but no autonomic symptoms (Group III) and 15 diabetics with autonomic symptoms (Group IV). We also studied R-R interval variation (CV: Coefficient of Variation) as a parameter of parasympathetic function and compared this with sympathetic function. Upon standing, blood pressure (BP) dropped precipitously in Group IV, whereas no significant changes were observed in the other three groups. Heart rate (HR) increased in Groups I and II, but not in Groups III and IV. During handgrip, BP and HR did not change significantly in all groups. Basal NE levels in Group IV were significantly smaller than those in Group I. NE responses to both standing and handgrip stimuli were markedly reduced in Group IV and, even in Group III, increments were significantly smaller than those in Groups I and II. Basal E levels did not differ, and significant changes were not observed after standing and handgrip in all groups. Both plasma renin activity (PRA) and plasma aldosterone concentrations (PAC) in Groups III and IV were lower than those in Groups I and II at rest and standing. After smoking, both BP and HR increased significantly in Groups I, II and III, whereas no changes were observed in Group IV. Both NE and E responses were markedly reduced in Group IV and, even in Group III, responses were significantly smaller than those in Groups I and II. CV in Groups III and IV were significantly smaller than those in Groups I and II. In diabetics, CV was strongly correlated with NE increments after standing (r = 0.78, p less than 0.01). Also, CV was correlated with both NE and E increments after smoking (r = 0.71 (NE), r = 0.82 (E), p less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)     

Changes in plasma norepinephrine after intravertebral artery infusion of saralasin in sodium depleted dogs

This study was designed to investigate the central action of circulating angiotensin II on the regulation of blood pressure in sodium depleted states. The effects of intravertebral arterial infusion of angiotensin II and [Sar-1, Ala-8] angiotensin II (saralasin) on plasma norepinephrine (NE) were studied in alpha-chloralose anesthetized dogs. Intravertebral arterial infusion of angiotensin II (10 ng/kg/min) increased mean arterial pressure (MAP), heart rate (HR) and plasma NE. Plasma NE was decreased by intravertebral arterial infusion of saralasin (0.40 +/- 0.05 to 0.28 +/- 0.04 ng/ml, p less than 0.05) in normal dogs. The administration of furosemide produced significant increases in plasma NE (142.4 +/- 23.7%, p less than 0.01), plasma renin activity (PRA) (158.6 +/- 26.3%, p less than 0.01) and HR (32.3 +/- 6.0 beats/min, p less than 0.01). A slight rise in mean blood pressure (3.9 +/- 1.2 mmHg, p less than 0.05) was observed during the furosemide administration. Saralasin infused into the vertebral artery significantly suppressed the furosemide-induced increases in plasma NE, HR and PRA, and lowered mean arterial blood pressure. Intravenous infusion of the same dose of saralasin produced no changes in arterial blood pressure, HR and plasma NE. These results suggest that the central sympathetic potentiation induced by circulating angiotensin II may contribute to the regulation of blood pressure in sodium and volume depleted states produced by furosemide.     

p15基因在多发性骨髓瘤中的甲基化异常及其意义

目的：探讨p15基因甲基化与多发性骨髓瘤的发生、发展及预后的关系。方法：采用甲基化特异性聚合酶链反应（MSP）研究33例多发性骨髓瘤（MM）及20例对照组的p15基因甲基化情况。结果：33例MM患者中有24例p15基因发生甲基化，20例对照组中无p15基因甲基化存在，差异有统计学意义（P〈0.01）。MM患者组中8例Ⅰ期、Ⅰ例Ⅱ期骨髓象为分化成熟的浆细胞型MM，p15基因未发生甲基化；在Ⅰ、Ⅱ、Ⅲ期中为浆细胞型或混合型中的幼稚浆细胞病例易发生甲基化，两者差异有统计学意义（PdO．01）。在Ⅰ、Ⅱ、Ⅲ期中p15基因甲基化率分别为27．27%（3／11例）、92．31％（12／13例）、100%（9／9例），Ⅱ、Ⅲ期甲基化率明显高于Ⅰ期（均P〈0．01）。结论：p15基因甲基化可能是MM发病的原因之一，与MM的发展及预后有一定的关系。     

Provocation of coronary vasospastic angina using an isoproterenol head-up tilt test

The goals of this study were to determine the value of the isoproterenol (ISO) head-up tilt (HUT) test in detecting coronary vasospastic angina and to investigate the possible mechanism responsible for coronary artery spasm. The ISO + HUT test was performed in 16 patients with coronary artery spasm documented by the intracoronary ergonovine provocation test. Patients' blood pressure and heart rate were measured at baseline, during the ISO + HUT (phase I), and during HUT after discontinuation of ISO (phase II). Patients were categorized as test-positive if they developed angina with ST-segment elevation during testing. Eight patients (50%) were test-positive (5 in phase I and 3 in phase II). Between the test-positive and test-negative groups, no significant differences were noted in the changes in blood pressure throughout the test. However, there were significant differences in the changes in heart rate from supine to 2 minutes after HUT under ISO infusion (-17 +/-22 vs 11 +/-25 beats/minute; p=0.035). In those patients with a positive result in the phase I stage, the heart rate decreased initially after tilt-up, and then significantly increased later (from 85 +/-16 to 110 +/-27 beats/minute; p=0.043), when coronary vasospasm occurred. In those patients with a positive result in the phase II stage, coronary vasospasm occurred immediately after HUT, when there was an insignificant transient increase in heart rate from the supine to the HUT position (from 85 +/-12 to 92 +/-11 beats/minute; p=0.109). The ISO + HUT test can provoke coronary vasospasm with ST-segment elevation in 50% of the patients with coronary artery spasm, when combined with an extensional protocol of HUT after discontinuation of ISO. This study suggests that the induction of coronary artery spasm during HUT testing is associated with a rapid elevation of sympathetic activity during augmented parasympathetic activity.     

倾斜试验过程中血浆内皮素的变化及意义

目的 :探讨血管迷走性晕厥 (VS)患者倾斜试验过程中血浆内皮素 (ET)水平的变化及其意义。　　方法 :接受倾斜试验的 42例 VS患者基础倾斜试验阳性反应 (基础阳性组 ) 14例 ,异丙肾上腺素 (ISO)激发阳性反应(ISO阳性组 ) 2 1例 ,阴性反应 (ISO阴性组 ) 7例。11例正常健康人倾斜试验呈阴性反应 (对照组 )。在倾斜试验前 ,倾斜后5、2 0、45分及试验结束或阳性反应时采集外周静脉血 ,以放射免疫法测定血浆 ET水平。　　结果 :ISO阳性组阳性反应时血压显著下降 ,ISO阴性组血压始终稳定。试验前有晕厥史者 3组的血浆 ET水平显著高于对照组。倾斜后 5分 ,各组血浆 ET水平显著升高 (P均 <0 .0 1) ;2 0分又明显下降 (P均 <0 .0 1) ,与倾斜前相似 (P均 >0 .0 5 )。阳性反应时或试验结束时 ,各组血浆 ET水平与 45分时相似 ,但仍明显高于倾斜前。　　结论 :VS患者倾斜前基础状态下血浆 ET水平升高。倾斜后血浆 ET水平的变化与倾斜试验结果无直接关系 ,只是机体对体位改变或长时间倾斜后的一种代偿性反应。     

False positive head-up tilt: hemodynamic and neurohumoral profile

OBJECTIVES: This study examined differences in mechanisms of head-up tilt (HUT)-induced syncope between normal controls and patients with neurocardiogenic syncope. BACKGROUND: A variable proportion of normal individuals experience syncope during HUT. Differences in the mechanisms of HUT-mediated syncope between this group and patients with neurocardiogenic syncope have not been elucidated. METHODS: A 30-min 80 degrees HUT was performed in eight HUT-negative volunteers (Group I), eight HUT-positive volunteers (Group II) and 15 patients with neurocardiogenic syncope. Heart rate and blood pressure (BP) were monitored continuously. Epinephrine and norepinephrine plasma levels, as well as left ventricular dimensions and contractility determined by echocardiography, were measured at baseline and at regular intervals during the test. RESULTS: The main findings of this study were the following: 1) All parameters were similar at baseline in the three groups; and 2) During tilt: a) the time to syncope was shorter in Group III than in group II (9.5 +/- 3 vs. 17 +/- 3 min p < 0.05); b) there was an immediate, persisting drop in mean BP in Group III; c) the decrease rate of left ventricular end-diastolic dimensions was greater in Group III than in Group II or Group I (-1.76 +/- 0.42 vs. -0.87 +/- 0.35 and -0.67 +/- 0.29 mm/min, respectively, p < 0.05); d) the leftventricular shortening fraction was greater in Group III than in the other two groups (39 +/- 1 vs. 34 +/- 1 and 32 +/- 1%, respectively, p < 0.05); and e) although the norepinephrine level remained comparable among the groups, there was a significantly higher peak epinephrine level in Group III than in Group II and Group I (112.3 +/- 34 vs. 77.6 +/- 10 and 65 +/- 12 pg/ml, p < 0.05). CONCLUSIONS: Mechanisms of syncope during HUT appeared to be different in normal volunteers and patients with neurocardiogenic syncope. In the latter, there was evidence of an impaired vascular resistance response from the beginning of the orthostatic challenge. Furthermore, in the patients there was more rapid peripheral blood pooling, as indicated by the echocardiographic measurements of left ventricular end-diastolic changes, leading to more precocious symptoms. In syncopal patients, the higher level of plasma epinephrine probably mediated the increased cardiac contractility and possibly contributed to the impaired vasoconstrictive response.     

Relationship between insulin resistance assessed by HOMA-IR and exercise test variables in asymptomatic middle-aged patients with type 2 diabetes

We investigated the relationship between index of insulin resistance (IR) and exercise test variables in middle-aged asymptomatic patients with Type 2 diabetes. METHODS: 90 patients (48 men, 42 women; age: 49 +/- 6 yr) were included in the study. We used homeostasis model assessment for IR (HOMA-IR) index as index of IR. All patients were subjected to treadmill exercise test. Four subjects were tested positive (4.4%). Study patients were separated into three groups: group I (no.=26) HOMA-IR index <2.24; group II (no.=26) index 2.24-3.59; group III (no.=38) index >3.59. RESULTS: group I had less frequency of cardiovascular risk factors than group II and III (p=0.001). Systolic blood pressure baseline as well as peak exercise values, were higher in group III than in group I and II (p=0.048 vs p=0.01, respectively). Higher total exercise time and peak workload were found in group I than group II and III (p=0.04). The recovery of heart rate (delta HR(pr)) was similar among the study groups. We found significant negative correlations between HOMA-IR and total exercise time and peak workload. In addition we found significant negative correlations between age vs chronotrophic index (CI), delta HR(pr), and peak workload. There were also similar negative correlations between duration of diabetes vs CI and delta HR(pr). CONCLUSIONS: IR is associated with a variety of cardiovascular risk factors. Some exercise test variables point out changes of autonomic tone during exercise in elevated IR group. Negative correlation between HOMA-IR and peak exercise capacity (METs) may well confirm increased mortality in hyperinsulinemia.     

Effects of orthostatic stress on forearm endothelial function in normal subjects and in patients with hypertension, diabetes, or both diseases

BACKGROUND: Sympathetically mediated vasoconstriction, to compensate for reduced venous return and cardiac output, characterizes the circulatory adaptation to head-up tilting (HUT). It has not been clarified whether this is coupled with a modulating endothelial vasorelaxation and whether diseases causing endothelial dysfunction, such as diabetes and hypertension, may impair this counterregulatory mechanism. METHODS: In patients with hypertension (group 1), diabetes (group 2), or both diseases (group 3) and in healthy control subjects (12 subjects per group) we investigated the brachial artery vasodilating response to the release of distal circulatory arrest (DCA) while they were supine and during 60 degrees HUT. RESULTS: The supine increase in lumen was smaller (P<.01) in groups 1 (+4.5%+/-1.5%), 2 (+4.8%+/-1.4%), and 3 (+3.9%+/-1.3%) than in the control group (+8.6%+/-1.6%). Vasorelaxation by nitroglycerin was similar in each population. During HUT, the lumen response to DCA was enhanced (P<.01 v supine) in control subjects (+15.4%+/-2.5%) and group 1 (+10.0+/-2.4%) and was reduced (P<.01 v supine) in groups 2 (+2.9%+/-0.5%) and 3 (+2.1%+/-0.4%), even though the hyperemic reaction to DCA was similar. The ratio of lumen changes to changes in flow (mm/mL/min x 1000) during reactive hyperemia to DCA increased (P<.01) with HUT, compared with that in the supine position, in control subjects (1.75v1.19) and group 1 (1.61v0.95), and decreased (P<.01) in groups 2 (0.62v0.87) and 3 (0.48v0.77). CONCLUSIONS: The HUT posture is characterized by an increased endothelium-dependent, flow-mediated vasodilation as a possible modulator of the neural vasoconstriction. This effect is persistent but blunted in hypertension and is abolished in diabetes, either alone or in association with high BP. Thus, vasoconstrictor factors could remain unmodulated during an event such as orthostasis, making the risk posed by these disorders more critical.     

Age and alpha-2 adrenergic regulation of plasma norepinephrine kinetics in humans

To investigate whether the age-related elevation of plasma norepinephrine (NE) is due to impaired alpha-2 adrenergic inhibition of sympathetic nervous system (SNS) outflow, arterialized plasma NE kinetics were measured before and 120 to 140 min after 1.5 and 5.0 micrograms m/kg oral clonidine in 6 old (57 to 78 years) and 8 young (25 to 39 years) normotensive male volunteers. Baseline plasma NE levels were higher in old compared with young men (M +/- SEM, 355 +/- 58 vs. 197 +/- 22 pg/ml, p less than .02). Clonidine produced significant (p less than .05) dose-related reductions in plasma NE, NE appearance rate, NE clearance, and mean arterial blood pressure (MAP) in both groups. There was no difference between old and young men in response to low dose clonidine. Following the higher dose, both groups had similar suppression of plasma NE (-51 +/- 7% vs. -58 +/- 2%, p greater than .05) and NE appearance (-60 +/- 6% vs. -62 +/- 2%, p greater than .05), but older men had a greater fall in NE clearance (-20 +/- 2% vs. -10 +/- 1%, p less than .003) and MAP (-28 +/- 3% vs. -10 +/- 4%, p less than .006). These findings suggest that sensitivity to alpha-2 receptor-mediated suppression of plasma NE and NE appearance is not diminished in elderly men.     

Usefulness of physical maneuvers for prevention of vasovagal syncope.

BACKGROUND: It is known that approximately two-thirds of patients with vasovagal syncope have prodromal symptoms and when these start, physical maneuvers that can increase venous return may abort the syncopal attack. The aims of this study were to evaluate the effects of 3 physical maneuvers, squatting, leg-crossing with muscle tensing, and handgrip, on improving hemodynamic status, and to compare the effect of each on aborting or preventing vasovagal syncope. METHODS AND RESULTS: Of 50 patients who underwent the head-up tilt test (HUT) to evaluate syncope, 27 patients with positive HUT were classified as group I (14 men, 13 women; mean age 44.5+/-15.3 years), 23 patients with negative HUT were classified as group II (13 men, 10 women; mean age 41.2 +/-16.7 years), and 21 normal subjects were classified as group III (10 men, 11 women; mean age 28.6+/-6.3 years). The effects of the physical maneuvers were evaluated in 21 patients from group I who underwent a repeat HUT 1 week after the initial test. Leg-crossing significantly increased systolic blood pressure (SBP) in all 3 groups (8.0+/-5.8 mmHg in group I, 7.0+/-8.5 mmHg in group II, 8.7+/-5.7 mmHg in group III; p < 0.05), but not diastolic blood pressure (DBP). Squatting significantly increased SBP and DBP in all 3 groups (7.1 +/-5.1, 4.6+/-5.8 mmHg in group I, 7.8+/-5.9, 4.3+/-4.7 mmHg in group II, 6.5+/-5.0, 3.7+/-3.9 mmHg in group III; p < 0.05). However, handgrip did not exert any significant influence on the hemodynamics in any group nor did heart rate change significantly during the physical maneuvers in any group. During the repeat HUT, prodromal symptoms with hypotension developed in 13 of the 21 patients and of these 5 fainted immediately after and were not able to do the physical maneuvers. Squatting and leg-crossing aborted syncope in 7 of 8 patients, but handgrip aborted syncope in only 1 patient. CONCLUSION: Squatting and leg-crossing with muscle tensing improved the hemodynamics of normal subjects as well as those of patients with vasovagal syncope. Squatting and leg-crossing can be used as a simple and effective preventive maneuver in patients with vasovagal syncope.