激光多普勒对糖尿病小鼠微循环自律运动功能的评估

目的:探讨激光多普勒对糖尿病小鼠微循环自律运动功能的评估价值。方法:20只BALB/c小鼠随机分为糖尿病组(n=10)和对照组(n=10)。连续5天腹腔注射40 mg/kg STZ诱导糖尿病模型;应用Moor LDLS检测糖尿病小鼠皮肤微循环血流灌注水平;应用Moor VMS-LDF检测糖尿病小鼠胰腺微循环血流灌注及微血管自律运动功能。结果:糖尿病小鼠皮肤微循环血流灌注显著降低,皮肤总血流灌注量(P=0.009)、胰腺微血管自律运动频率(P0.001)和振幅(P0.001)均显著低于对照组小鼠。结论:联合应用Moor LDLS激光多普勒扫描成像系统及Moor VMS-LDF激光多普勒血流灌注监测系统可作为糖尿病小鼠微循环功能状态的评估手段。     

脑缺血后的脑微血管变化

大脑微血管具有独特的组织结构,这种结构对脑组织起到了保护性屏障作用,局部脑缺血可以引起这种屏障功能破坏,导致血液成分渗出,以及与炎症反应密切相关的整合素表达明显增加,促使炎性细胞以及血小板等向缺血局部聚集和迁移,从而造成局部微血管阻塞。同时,血管内皮细胞基质金属蛋白酶表达明显增加,内皮细胞和星形胶质细胞表面的结构整合素以及对应的基质配体丢失,使微血管细胞间的紧密联系破坏。以上这些变化伴随着神经细胞的损伤,同时,与血管生成和神经发生相关的受体上调,缺血局部区域出现血管生成和神经发生现象,这些过程可能与缺血后期脑功能的恢复相关。本文主要就脑缺血以后脑微血管的变化进行了综述,并对其中的问题以及今后脑血管病研究的发展进行了探讨。     

血小板与心肌缺血

心肌缺血时发生的血小板功能异常变化,可减少冠脉侧枝流入缺血区的血量,造成缺血后心脏电活动异常,并加重泵功能衰竭,进而扩大缺血范围,增加梗塞死亡率。缺血后的神经、体液和血管等因素改变有引致血小板功能变化的作用,但尚需进一步澄清其作用原理。     

清栓酶治疗脑血栓冠心病微循环变化初步观察

本文报导40例脑心血管疾病在清栓酶治疗前后进行甲皱微循环对比观察,其中脑血栓组20例,冠心病组20例,两组均在清栓酶治疗2～3疗程后复查,分别对其甲皱微循环微血管袢的形态及功能,血液流态和微血管周围变化等三方面进行治疗前后对比观察,结果发现,治疗前甲皱微循环改变是明显的,临床症状较重,治疗后甲皱微循环障碍均得到了明显改善,临床症状也随着减轻或消失。治疗前后比较,其差异有显著的意义 P<0.05,P<0.01.从临床对比观察所见,脑心血管疾病的微循环改变与病情有关,其改变与病情轻重相吻合,与疾病转归相一致,提示微血管病变是动脉硬化临床可识别的象征.微循环障碍与疾病的发生发展有着内在联系,是脑心血管疾病的病因和发病的中间环节.治疗后微循环障碍的明显改善,提示清栓酶有着较好的改善微循环的功能.     

运动对大鼠体内锌代谢及H~＋─转运ATP酶的影响

本实验初步观察了运动过程中大鼠体内锌的变化情况以及运动对大鼠心肌线粒体能量转换功能的影响。结果提示：一次力竭运动可使大鼠体内锌代谢发生改变,变化的原因可能与摄入不足、运动机体需要增加等有关。一定强度的运动训练不足以使心肌线粒体功能发生明显改变,但一次力竭性运动可以导致心肌线粒体膜的流动性发生明显变化,Ｈ＋转运ＡＴＰ酶活性明显降低。     

大鼠局灶性脑缺血后星形胶质细胞过度增殖对局部微循环的影响

目的 观察局灶性脑缺血后海马和缺血边缘区星形胶质细胞过度增殖对微循环的影响。方法将大鼠随机分为假手术组、缺血组和干预组,缺血组和干预组采用线栓法制备大脑中动脉栓塞模型,缺血组侧脑室采用ALZET微渗透泵给予0．2％DMSO,干预组给予细胞周期抑制剂roscovitine,假手术组不插入线栓,不给与任何药物干预。缺血7d后于股静脉注入FITC标记的葡聚糖标记血管,小鼠抗大鼠单克隆抗胶质纤维酸性蛋白（glial fibrillary acidic protein,GFAP）抗体标记星形胶质细胞;激光共聚焦三维成像显示胶质细胞于微循环之间的关系。结果缺血同侧海马和缺血边缘区在GFAP阳性细胞增多的同时,局部微血管血流灌注明显减少,应用细胞周期抑制剂roscovitine抑制星形胶质细胞增生可以明显增加局部微血管的血流灌注。结论脑缺血后缺血边缘区和海马的反应性星形胶质细胞增生与微循环灌注减少密切相关。     

糖尿病肾病蛋白尿发生机制的研究进展

糖尿病肾病蛋白尿的发生发展是多因素综合作用的结果.虽然蛋白尿的确切病因仍未清楚,但基本是由肾脏血流动力学改变、肾小球滤过屏障异常、多种生长因子、细胞因子、免疫炎症因子异常表达以及肾小管异常等多个因素综合所致.在分子水平上,氧化应激是糖尿病并发症发生的早期事件.此外,内皮细胞结构异常和功能紊乱以及肾小管重吸收功能异常可能也参与了蛋白尿的发生发展.本文着重探讨糖尿病肾病蛋白尿发生的细胞及分子机制研究进展,为更好的防治糖尿病肾病提供有力的依据.     

运动对大鼠休内锌代谢及H^＋—转运ATP酶的影响

本实验初步观察了运动过程中大鼠体内锌的变化情况以及运动对大鼠心肌线粒体能量转换功能的影响。结果提示：一次力褐运动可使大鼠体内锌代谢代发生改变,变化的原因可能与摄入不足、运动机体需要增加等有关。一定强度的运动训练不足以使心肌线粒体功能发生明显改变,但一次力竭性运动可以导致心肌线粒体膜的流动性发生明显变化,Ｈ＾＋转运ＡＴＰ酶活性明显降低。     

有氧运动与干细胞动员的缺血心脏血管新生研究进展

有氧运动具有明确的血管新生效应,包括缺血心脏,但其机制尚未完全阐明。心肌梗死(MI)后冠脉微血管新生是心脏修复的前提。新近研究表明,血管新生来源于体内干/祖细胞的动员与参与,并以旁分泌效应影响内皮细胞(EC)功能及微血管分布效果,运动可以动员、激活内源性干细胞因子和血管生成因子的表达与分泌,并能从表观遗传学角度影响心脏血管新生。探索不同运动方式及强度对缺血心脏血管新生的作用及其分子机制,对缺血心脏的预防及术后康复具有重要意义。本文从心脏血管新生及其调控机制、自体干细胞动员参与缺血心脏的血管新生和运动通过干细胞动员促进缺血心脏血管新生等方面综述运动促进缺血心脏血管新生的主要机制、存在问题及相关研究进展。     

运动：一种双向调控疾病中自噬异常的手段

自噬(autophagy)是一种进化上高度保守的细胞降解过程,它可以完成细胞成分的基本周转,并提供能量和大分子前体以维持生物体的代谢与平衡。近年研究发现,细胞自噬水平的失调与多种疾病的发生和发展密切相关,这一点已在多种疾病动物模型中得到验证。过高或不足的自噬水平都可能导致疾病。运动作为一种与能量代谢及细胞内环境变化密切相关的活动,与细胞自噬过程之间有密切关联。而运动对自噬的调节是一个双向的过程。对于自噬不足或过度引起的疾病,运动可以恢复其正常的自噬功能,并起到改善、延缓疾病进展的作用。当前,对于运动调控疾病背景下异常的自噬水平的理论及机制尚缺乏充分的阐述。深入探索和讨论运动对疾病中异常自噬水平的调节,将有助于我们拓展视野,为更全面地理解运动在预防和改善各种与自噬相关的疾病过程中的潜在机制和作用。因此,本综述分析概括总结了运动改善疾病中过高或不足的自噬水平及运动对疾病的缓解效果,梳理了运动与自噬的双向调控关系,并进一步提炼归纳了运动调控异常自噬水平所涉及的相关信号通路。这为探究运动促进健康的机制及理清运动调控自噬之间的关系提供理论依据与参考。     

Impaired microvascular perfusion: a consequence of vascular dysfunction and a potential cause of insulin resistance in muscle

Insulin has an exercise-like action to increase microvascular perfusion of skeletal muscle and thereby enhance delivery of hormone and nutrient to the myocytes. With insulin resistance, insulin's action to increase microvascular perfusion is markedly impaired. This review examines the present status of these observations and techniques available to measure such changes as well as the possible underpinning mechanisms. Low physiological doses of insulin and light exercise have been shown to increase microvascular perfusion without increasing bulk blood flow. In these circumstances, blood flow is proposed to be redirected from the nonnutritive route to the nutritive route with flow becoming dominant in the nonnutritive route when insulin resistance has developed. Increased vasomotion controlled by vascular smooth muscle may be part of the explanation by which insulin mediates an increase in microvascular perfusion, as seen from the effects of insulin on both muscle and skin microvascular blood flow. In addition, vascular dysfunction appears to be an early development in the onset of insulin resistance, with the consequence that impaired glucose delivery, more so than insulin delivery, accounts for the diminished glucose uptake by insulin-resistant muscle. Regular exercise may prevent and ameliorate insulin resistance by increasing "vascular fitness" and thereby recovering insulin-mediated capillary recruitment.     

Network thermodynamic analysis of vasomotion in a microvascular network.

The modulation of microvascular blood flow by vasomotion in the individual vessels of a simple vascular network was simulated by means of a network thermodynamic model. The flow is driven under a pulsating pressure through two arcades of branching vasoactive arterioles into a passive resistance representing the capillary and venular beds. Each vessel was assumed to have the capability of decreasing rhythmically the local diameter over a short section by a specified fraction of the maximum value and to change the average diameter along its total length in response to alterations in intraluminal pressure. Blood was assumed to exhibit a simple linear viscous flow resistance. Alterations in flow rate and distribution through the network were determined as a function of the magnitude and frequency of vasomotion within the individual arterioles supplying blood to the microvascular bed. Specific cases are shown to illustrate how blood flow can be influenced by the patterns of vasomotion within the network.     

Increased rhythmicity in hypertensive arterial smooth muscle is linked to transient receptor potential canonical channels

Vasomotion describes oscillations of arterial vascular tone due to synchronized changes of intracellular calcium concentrations. Since increased calcium influx into vascular smooth muscle cells from spontaneously hypertensive rats (SHR) has been associated with variances of transient receptor potential canonical (TRPC) channels, in the present study we tested the hypothesis that increased vasomotion in hypertension is directly linked to increased TRPC expression. Using a small vessel myograph we observed significantly increased norepinephrine‐induced vasomotion in mesenteric arterioles from SHR compared to normotensive Wistar–Kyoto (WKY) rats. Using immunoblottings we obtained significantly increased expression of TRPC1, TRPC3 and TRPC5 in mesenteric arterioles from SHR compared to WKY, whereas TRPC4 and TRPC6 showed no differences. Norepinephrine‐induced vasomotion from SHR was significantly reduced in the presence of verapamil, SKF96365, 2‐aminoethoxydiphenylborane (2‐APB) or gadolinium. Pre‐incubation of mesenteric arterioles with anti‐TRPC1 and anti‐TRPC3 antibodies significantly reduced norepinephrine‐induced vasomotion and calcium influx. Control experiments with pre‐incubation of TRPC antibodies plus their respective antigenic peptide or in the presence of anti‐β‐actin antibodies or random immunoglobulins not related to TRPC channels showed no inhibitory effects of norepinephrine‐induced vasomotion and calcium influx. Administration of candesartan or telmisartan, but not amlodipine to SHR for 16 weeks significantly reduced either the expression of TRPC1, TRPC3 and TRPC5 as well as norepinephrine‐induced vasomotion in mesenteric arterioles. In conclusion we gave experimental evidence that the increased TRPC1, TRPC3 and TRPC5 expression in mesenteric arterioles from SHR causes increased vasomotion in hypertension.     

Vasomotion: the case for chaos

Fluctuations in vascular calibre, a phenomenon known as vasomotion, are ubiquitous in the microcirculation and represent emergent behaviour that involves synchronisation of Ca²⁺ oscillations in individual vascular cells. Ideally, coordinated interactions between locally generated vasomotion and neuro-humoral control mechanisms will allow optimal sensing of flow and pressure within vascular networks and thereby facilitate synergistic readjustments in local vascular conductance and flow under conditions of dynamically changing metabolic demand. Indeed, many studies have reported that vasomotion becomes more prominent under pathophysiological conditions, suggesting that it may serve as an adaptive homeodynamic response that maintains or re-establishes flow when perfusion is compromised. We here summarise evidence that the apparent irregular nature of vasomotion reflects deterministic interactions between a small number of dominant control variables, rather than random events, and may therefore be formally classified as chaotic. We also discuss the potential physiological benefits of chaos in the microcirculation and the key roles of signalling via gap junctions and nitric oxide.     

Microalbuminuria in Type 2 diabetes indicates impaired microvascular vasomotion and perfusion

Vascular oscillation (vasomotion) occurs in the microcirculation and is thought to be a significant contributor to tissue perfusion. Our aims were to assess the relationship of vasomotion to perfusion in the cutaneous microcirculation of diabetic patients, to determine the influence on it of endothelium-dependent and nonendothelium-dependent vasodilatory stimuli, and to assess the relationship to perfusion and vasomotion of various biochemical markers of vascular function (HbA1c, LDL- and HDL-cholesterol, triglycerides, insulin resistance, high sensitive C-reactive protein, L- and E-selectin, soluble ICAM, von Willebrand factor) and microalbuminuria. Perfusion and vasomotion (spectral density at low and very low frequencies) were measured by laser-Doppler flowmetry after local heat and iontophoresis of ACh and sodium nitroprusside. Perfusion responses to all stimuli were impaired in patients with Type 2 diabetes (heat: F = 28.0, P < 0.001; ACh: F = 7.11, P = 0.003; sodium nitroprusside: F = 4.0, P = 0.028). Responses to endothelium-dependent stimuli were further impaired in microalbuminuric patients (heat: P = 0.035; ACh: P = 0.034). Vasomotion responses at low frequencies after endothelium-dependent stimuli were impaired in diabetic patients compared with that shown in controls (heat: F = 5.62, P = 0.002; ACh: F = 4.32, P = 0.015). Multivariate modeling showed microalbuminuria to be the only consistent predictor of perfusion and vasomotion responses. The results suggest that microalbuminuria in Type 2 diabetes reflects a generalized disturbance of microvascular function related to endothelium-dependent mechanisms.     

Small artery remodelling in diabetes

The aim of this article is to briefly review available data regarding changes in the structure of microvessels observed in patients with diabetes mellitus, and possible correction by effective treatment. The development of structural changes in the systemic vasculature is the end result of established hypertension. In essential hypertension, small arteries of smooth muscle cells are restructured around a smaller lumen and there is no net growth of the vascular wall, although in some secondary forms of hypertension, a hypertrophic remodelling may be detected. Moreover, in non-insulin-dependent diabetes mellitus a hypertrophic remodelling of subcutaneous small arteries is present. Indices of small resistance artery structure, such as the tunica media to internal lumen ratio, may have a strong prognostic significance in hypertensive and diabetic patients, over and above all other known cardiovascular risk factors. Therefore, regression of vascular alterations is an appealing goal of antihypertensive treatment. Different antihypertensive drugs seem to have different effect on vascular structure. In diabetic hypertensive patients, a significant regression of structural alterations of small resistance arteries with drugs blocking the renin–angiotensin system (angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers) was demonstrated. Alterations in the microcirculation represent a common pathological finding, and microangiopathy is one of the most important mechanisms involved in the development of organ damage as well as of clinical events in patients with diabetes mellitus. Renin–angiotensin system blockade seems to be effective in preventing/regressing alterations in microvascular structure.     

Resveratrol reduction of infarct size in Long-Evans rats subjected to focal cerebral ischemia

Although vasomotion has been considered a feature of the microvascular bed under physiological conditions, it has also been observed following hypotension in several tissues. In this work, 158 mesenteric microvessels of 36 rats were investigated quantitatively in normovolemic and hemorrhaged animals, focussing on diameter changes, particularly vasomotion incidence and characteristics. The femoral arteries of Wistar rats (body weight BW = 188 +/- 23 g, mean +/- SD) anesthetized with pentobarbital were cannulated for arterial pressure (AP) monitoring and blood withdrawal. The protocol consisted of 15 min control and 30 min of hemorrhagic hypotension (AP = 52 +/- 5 mmHg, hemorrhaged vol. = 17 +/- 4 ml/kg BW). During control normovolemic conditions, analysis of mesenteric microcirculation using intravital videomicroscopy revealed neither arteriolar nor venular vasomotion. During hemorrhagic hypotension (HH) microvascular blood flow reduced to 25% of control. While venules did not show diameter changes during HH, arterioles contracted to 85 +/- 20% of control and arteriolar vasomotion appeared in 42% of the animals and 27% of the arterioles. The amplitude of arteriolar diameter change during HH relative to mean diameter and to control diameter averaged 65 +/- 24% (range: 32-129%) and 41 +/- 10% (range: 25-62%), respectively. Vasomotion analysis showed two major frequency components: 1.7 +/- 0.8 and 7.0 +/- 5.2 cycles/min. Arterioles showing vasomotion had a mean control diameter larger than the remaining arterioles and showed the largest constriction during HH. We conclude that hemorrhagic hypotension does not change venular diameter but induces arteriolar constriction and vasomotion in rat mesentery. This activity is expressed as slow waves with high amplitude and fast waves with low amplitude, and is dependent on vessel size.     

Lung-selective gene responses to alveolar hypoxia: potential role for the bone morphogenetic antagonist gremlin in pulmonary hypertension

Pulmonary hypoxia is a common complication of chronic lung diseases leading to the development of pulmonary hypertension. The underlying sustained increase in vascular resistance in hypoxia is a response unique to the lung. Thus we hypothesized that there are genes for which expression is altered selectively in the lung in response to alveolar hypoxia. Using a novel subtractive array strategy, we compared gene responses to hypoxia in primary human pulmonary microvascular endothelial cells (HMVEC-L) with those in cardiac microvascular endothelium and identified 90 genes (forming 9 clusters) differentially regulated in the lung endothelium. From one cluster, we confirmed that the bone morphogenetic protein (BMP) antagonist, gremlin 1, was upregulated in the hypoxic murine lung in vivo but was unchanged in five systemic organs. We also demonstrated that gremlin protein was significantly increased by hypoxia in vivo and inhibited HMVEC-L responses to BMP stimulation in vitro. Furthermore, significant upregulation of gremlin was measured in lungs of patients with pulmonary hypertensive disease. From a second cluster, we showed that CXC receptor 7, a receptor for the proangiogenic chemokine CXCL12, was selectively upregulated in the hypoxic lung in vivo, confirming that our subtractive strategy had successfully identified a second lung-selective hypoxia-responsive gene. We conclude that hypoxia, typical of that encountered in pulmonary disease, causes lung-specific alterations in gene expression. This gives new insights into the mechanisms of pulmonary hypertension and vascular loss in chronic lung disease and identifies gremlin 1 as a potentially important mediator of vascular changes in hypoxic pulmonary hypertension.     

Normal Muscle Oxygen Consumption and Fatigability in Sickle Cell Patients Despite Reduced Microvascular Oxygenation and Hemorheological Abnormalities

Background/Aim

Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue.

Methods

We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients.

Results

Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects.

Conclusions

Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit mitochondrial respiration but increases muscle microvascular blood flow.