磺脲类药物对胰岛β细胞凋亡影响的研究进展

磺脲类降糖药物目前广泛应用于2型糖尿病的临床治疗。它主要的降糖机制是通过与胰岛细胞膜上的磺脲类受体结合，关闭了由SUR1和KIR6．2组成的钾通道（KATP），导致了细胞膜的去极化，触发了L型钙离子通道开放，从而使钙离子大量内流，促进了胰岛细胞分泌胰岛素。但与此同时，大量钙离子内流，造成了胰岛细胞的钙超载，加之胰岛细胞活化过程中产生的大量氧自由基都造成了胰岛细胞的损伤。故很多文献报道，磺脲类药物对胰岛细胞有诱导凋亡作用，但机制各有不同。事实上，不同的磺腮茨药物对于胰岛β细胞凋亡的作用机制尚未完全明确，且有很多争论。新近研究表明，一些新型磺脲类药物剂型，如格列美脲对胰岛细胞凋亡的作用可能有所不同。     

胃肠胰胰岛淀粉样多肽的定位和表达

胰岛淀粉样多肽(islet armyloid polypeptide,IAPP)是1986年瑞典学者Westermarket al[1,2 ]从胰岛素瘤患者的瘤组织,糖尿病猫及Ⅱ型糖尿病患者胰岛淀粉样沉积物中分离出来的一种多肽,几乎在同时,英国生物化学家Cooper et al[3,4]也从Ⅱ型糖尿病患者的胰岛淀粉样沉积物中分离出该肽.IAPP又称为amylin.对IAPP的分子结构、基因表达和生理作用等已有许多报道[5].近年来,在IAPP定位、表达及胃肠胰IAPP免疫反应(immunoreactive,IR)细胞定位、发生、发育方面的研究报道,为探讨IAPP的生理作用及疾病状态下的改变,提供了形态学依据,现综述如下.     

苯那普利对缺氧复氧心肌心胞内钙离子的影响及机制研究

目的研究苯那普利对乳鼠缺氧复氧心肌细胞内钙离子浓度的影响及作用机制。方法采用纯化培养的乳鼠心肌细胞复制缺血再灌注模型。实验分为4组,每组8例：空白对照组、单纯缺氧复氧组（H／R）、缺氧复氧＋苯那普利（1×10^6mol／L）组、缺氧复氧＋苯那普利（1×10^6mol／L）＋缓激肽B2受体拮抗剂（HOE140）（1×10^6mol／L）组。细胞缺氧1h,复氧2h后取细胞培养液测定乳酸脱氢酶（LDH）,取细胞测定超氧化物歧化酶（SOD）的活性和丙二醛（MDA）含量,测定细胞内钙浓度。结果单纯缺氧复氧组与对照组比较,LDH、MDA、[Ca^2＋]i含量升高,SOD活性下降（P〈0．01）;苯那普利组与缺氧复氧组比较,LDH、MDA、[Ca^2＋]i含量降低,SOD活性升高（P〈0．01）;苯那普利＋HOE140组与苯那普利组比较,LDH、MDA、[Ca^2＋]i含量升高,SOD活性下降（P〈0．01）。结论苯那普利能降低细胞内钙离子浓度,有明显保护心肌的作用。其作用可能与激活激肽-缓激肽释放系统、抑制缓激肽的降解有关。     

脂欣康胶囊对大鼠血管平滑肌细胞源性泡沫细胞钙离子浓度的影响

目的观察脂欣康及洛伐他汀干预大鼠血管平滑肌细胞（VSMC）源性泡沫细胞产生的细胞内钙离子（[Ca^2＋]i）浓度变化，以探讨脂欣康对动脉粥样硬化（AS）泡沫化细胞形成的可能调控机制。方法用组织块培养法培养VSMC，以氧化低密度脂蛋白使其泡沫化，并以脂欣康、洛伐他汀分别干预。以10μmol／L的Fluo-3孵育细胞后，用激光共聚焦显微镜扫描、记录图像，并作分析。结果脂欣康与洛伐他汀均能降低VSMC[Ca^2＋]i浓度，与生理盐水组、空白对照组相比，脂欣康组和洛伐他汀组均有统计学意义（P〈0．01），但两组之间差异无统计学意义（P〉0．05）。结论脂欣康具有与洛伐他汀相似的降低VSMC[Ca^2＋]i浓度的作用，这可能是其抑制VSMC增殖和泡沫化细胞形成的机制之一。     

在新生糖尿病小鼠模型中减少Cx36间隙连接耦合可弥补异常活跃的ATP敏感性K^＋通道恢复胰岛素分泌

编码ATP敏感性K^＋通道（KATP通道）的基因突变会降低ATP抑制的敏感性,进而通过抑制B细胞葡萄糖刺激的游离钙（[Ca^2＋]i）的活性和胰岛素分泌,导致新生儿糖尿病。连接蛋白36（Cx36）的缝隙连接也调节胰岛细胞电活动;一旦Cx36基因敲除,在基础葡萄糖水平下,β细胞显示[Ca^2＋]i的升高。     

5种黄酮醇类化合物对大鼠心肌细胞内钙离子的影响

目的研究山萘酚（Kaempferol，KA）、杨梅素（Myricetin，MY）、二氢杨梅素（Dihydromyricetin，DMY）、槲皮素（Quercetin，Qu）、二氢槲皮素（Dihydroquercetin，DQU）5种黄酮醇类化合物对大鼠心肌细胞内游离钙离子（[Ca^2＋]i）的影响。方法采用Fluo-3／AM同时加入PluronicF-127作为细胞内游离钙离子的荧光探针，负载H9C2心肌细胞系，应用激光扫描共聚焦显微技术，测定5种黄酮醇类化合物（50μmol／L）在静息状态和加入60mmol／L氯化钾（KCl）时心肌细胞胞浆内游离钙离子的荧光强度（FI）。结果静息状态下，KA和Qu能够明显降低心肌细胞内[Ca^2＋]i（P〈0．05），MY能够短暂而明显升高[Ca^2＋]i（P〈0．05），而DMY和DQU对心肌细胞内[Ca2＋li无明显影响（P〉0．05）；KA、MY、DMY、Qu和DQU对KCl介导的高钙有抑制作用（P〈0．05）。结论5种黄酮醇类化合物对电压依赖性钙通道（VDC）有明显抑制作用，这可能是产生药理活性机制之一．有利于进一步研究其对心肌的保护作用和探讨其构效关系。     

大电导钙离子激活钾通道与糖尿病冠状动脉病变

钙离子（Ca^2＋）激活钾通道根据电导大小和药理特性的差异可分为3类：即大电导ca^2＋激活钾通道（BK）、中电导Ca^2＋激活钾通道（IK）和小电导Ca^2＋激活钾通道（SK），其中BK通道因其对血管调节作用较大且分布广泛而备受关注^[1].BK通道广泛存在于兴奋和非兴奋细胞，在血管平滑肌细胞（VSMCs）膜上表达尤为丰富，不仅参与细胞膜电位的。     

Sources of calcium in agonist-induced contraction of rat distal colon smooth muscle in vitro

AIM： To study the origin of calcium necessary for agonist-induced contraction of the distal colon in rats.METHODS： The change in intracellular calcium concentration （[Ca^2＋]i） evoked by elevating external Ca^2＋ was detected by fura 2/AM fluorescence. Contractile activity was measured with a force displacement transducer. Tension was continuously monitored and recorded using a Powerlab 4/25T data acquisition system with an ML110 bridge bioelectric physiographic amplifier.RESULTS： Store depletion induced Ca^2＋ influx had an effect on [Ca^2＋]i. In nominally Ca^2＋-free medium, the sarco-endoplasmic reticulum Ca^2＋-ATPase inhibitor thapsigargin （1 μmol/L） increased [Ca^2＋]i from 68 to 241 nmol/L, and to 458 （P 〈 0.01） and 1006 nmol/L （P 〈 0.01）, respectively, when 1.5 mmol/L and 3.0 mmol/L extracellular Ca^2＋ was reintroduced. Furthermore, the change in [Ca^2＋]i was observed with verapamil （5 μmol/L）, La3＋ （1 mmol/L） or KCl （40 mmol/L） in the bathing solution. These channels were sensitive to La3＋ （P 〈 0.01）, insensitive to verapamil, and voltage independent. In isolated distal colons we found that in normal Krebs solution, contraction induced by acetylcholine （ACh） was partially inhibited by verapamil, and the inhibitory rate was 41% （P 〈 0.05）. On the other hand, in Ca^2＋-free Krebs solution, ACh induced transient contraction due to Ca^2＋ release from the intracellular stores. The transient contraction lasted until the Ca^2＋ store was depleted. Restoration of extracellular Ca^2＋ in the presence of atropine produced contraction, mainly due to Ca^2＋ influx. Such contraction was not inhibited by verapamil, but was decreased by La3＋ （50 μmol/L） from 0.96 to 0.72 g （P 〈 0.01）. CONCLUSION： The predominant source of activator Ca^2＋ for the contractile response to agonist is extracellular Ca^2＋, and intracellular Ca^2＋ has little role to play in mediating excitation-contraction coupling by agonists in rat distal colo     

胞二磷胆碱对帕金森病模型中多巴胺能神经元的保护作用

目的 探讨胞二磷胆碱（citicoline,CC）对6-OHDA诱导的帕金森病体外细胞模型的神经保护作用机制.方法 MTT法检测细胞活力;采用Fluo3/AM通过流式细胞仪检测细胞内[Ca^2＋]i,采用罗丹明123检测线粒体膜电位（△ψm）.结果 2、1和0.1 mmol/L浓度的胞二磷胆碱,细胞活力与对照组比较明显增高（P＜0.01）,0.1 mmol/L组（P＜0.05）;1、0.1、0.01和0.001 mmol/L胞二磷胆碱能对抗由6-OHDA引起的多巴胺能神经元的损害,细胞活力高于6-OHDA组（P＜0.01）;胞二磷胆碱能对抗6-OHDA造成的细胞内[Ca^2＋]i增高及△ψm的下降（P＜0.01）;1 mmol/L胞二磷胆碱＋6-OHDA组△ψm高于对照组（P＜0.01）.结论 胞二磷胆碱通过保护神经元细胞膜,降低细胞内[Ca^2＋]i,提高线粒体膜电位,增强细胞活力,发挥其对多巴胺能神经元的保护作用.     

丹参酮ⅡA抑制血管紧张素Ⅱ诱导大鼠心肌肥大的机制

目的 在原代培养的新生大鼠心肌细胞的基础上，观察丹参酮ⅡA磺酸钠盐（STS）对血管紧张素Ⅱ（AngⅡ）诱导的心肌细胞肥大的影响，以探讨STS在钙调神经磷酸酶（CaN）依赖的信号通路心肌肥大中的作用。方法 以培养的原代心肌细胞为模型，用AngⅡ刺激细胞外Ca^2＋内流，丹参酮ⅡA及钙离子拮抗剂维拉帕米（Ver）进行干预。检测心肌细胞[Ca^2＋]i及钙调神经磷酸酶（CaN）、丝裂素活化蛋白激酶（MAPK）和蛋白激酶C（PKC）活性江。[^3H]-亮氨酸掺入法测定心肌细胞蛋白质合成速率作为心肌细胞肥大的指标。结果 AngⅡ刺激组[Ca^2＋]i水平及蛋白核酸合成速率明显增高，与对照组相比差异显著（P〈0．01），而STS能有效地降低南AngⅡ刺激引起的[Ca^2＋]i增高（P〈0．01VSAng1组）。明显抑制AngⅡ诱导的蛋白质合成速率的增加（P〈0．01 VS AngⅡ组）。AngⅡ刺激组CaN、PKC活性与对照组相比差异有显著性（P〈0．05、P〈0．01）。STS及Ver抑制AngⅡ介导的心肌细胞CaN、PKC活性的增高。结论 CaN通路在AngⅡ刺激的心肌细胞肥大中起重要作用；STS具有Ca^2＋阻滞剂的特点，能有效地降低由AngⅡ刺激引起的[Ca^2＋]i增高，导致CaN活性降低阻滞心肌肥大的发生和发展。     

Intramuscular islet transplantation promotes restored islet vascularity

In a recent publication, we reported that islets transplanted to mouse striated muscle became revascularized with intra-islet vessel densities comparable to native islets. Revascularization of islet grafts was completely dependent on recruited Gr-1+ leukocytes. Diabetic mice cured by transplantation of 300 islets into muscle handled glucose tolerance tests as healthy controls, whereas mice cured by intraportal islet transplantation into the liver had increased blood glucose values during the load. The translational impact of these observations were confirmed by magnetic resonance imaging of autotransplanted islets in the forearm muscle of pancreactomized patients, and higher blood perfusion of the grafts compared to adjacent muscle were found. In summary, the striated muscle is a promising site for islet transplantation which promotes full revascularization of implanted grafts. The proangiogenic role of recruited leukocytes during engraftment needs to be further characterized, and considered for immune suppression treatments.     

Intramuscular islet transplantation promotes restored islet vascularity

In a recent publication, we reported that islets transplanted to mouse striated muscle became revascularized with intra-islet vessel densities comparable to native islets. Revascularization of islet grafts was completely dependent on recruited Gr-1+ leukocytes. Diabetic mice cured by transplantation of 300 islets into muscle handled glucose tolerance tests as healthy controls, whereas mice cured by intraportal islet transplantation into the liver had increased blood glucose values during the load. The translational impact of these observations were confirmed by magnetic resonance imaging of autotransplanted islets in the forearm muscle of pancreactomized patients, and higher blood perfusion of the grafts compared to adjacent muscle were found. In summary, the striated muscle is a promising site for islet transplantation which promotes full revascularization of implanted grafts. The proangiogenic role of recruited leukocytes during engraftment needs to be further characterized, and considered for immune suppression treatments.     

Assessment of islet function following islet and pancreas transplantation

Pancreas and islet transplant recipients are monitored using various metabolic and imaging methods. The inaccessibility of the transplanted whole pancreas and of the isolated islets poses specific problems (eg, all assessment techniques are indirect). Although successful pancreas transplantation typically restores normal glucose homeostasis, islet transplantation into the liver does not completely normalize islet hormone secretion and glucose metabolism. Development of better testing strategies, such as direct islet imaging, will significantly advance the field.     

Pancreatic islet plasticity: Interspecies comparison of islet architecture and composition

The pancreatic islet displays diverse patterns of endocrine cell arrangement. The prototypic islet, with insulin-secreting β-cells forming the core surrounded by other endocrine cells in the periphery, is largely based on studies of normal rodent islets. Recent reports on large animals including humans show a difference in islet architecture, in which the endocrine cells are randomly distributed throughout the islet. This particular species difference has raised concerns regarding the interpretation of data based on rodent studies to humans. On the other hand, further variations have been reported in marsupials and some nonhuman primates, which possess an inverted ratio of β-cells to other endocrine cells. This review discusses the striking plasticity of islet architecture and cellular composition among various species including changes in response to metabolic states within a single species. We propose that this plasticity reflects evolutionary acquired adaptation induced by altered physiological conditions, rather than inherent disparities between species.     

Optimising islet engraftment is critical for successful clinical islet transplantation

Clinical islet transplantation is currently being explored as a treatment for persons with type 1 diabetes and hypoglycaemia unawareness. Although ‘proof-of-principle’ has been established in recent clinical studies, the procedure suffers from low efficacy. At the time of transplantation, the isolated islets are allowed to embolise the liver after injection in the portal vein, a procedure that is unique in the area of transplantation. A novel view on the engraftment of intraportally transplanted islets is presented that could explain the low efficacy of the procedure.     

糖尿病胰岛纤维化分子机制研究进展

大量病理研究发现,在1型和2型糖尿病患者及各种动物模型中,均可观察到胰岛纤维化现象.胰岛纤维化过程进一步破坏了胰岛的正常组织结构并导致胰岛功能恶化、β细胞数量减少、胰岛素分泌量降低.     

History of islet transplantation

Patients with a diagnosis of type 1 diabetes mellitus endure stringent life-long medical therapy through the use of insulin to prevent end organ complications and maintain normoglycemia. However, some patients still suffer from hypoglycemic unawareness, even under intensive therapy. Within the past decade, noble efforts have been attempted to provide normoglycemia through cadaveric islet of Langerhans transplantation in order to reach a physiologic response. This effort, which has evolved for more than a century, actually predates the discovery of insulin.