血糖变化对糖尿病大鼠骨骼肌GLUT4基因表达的影响

目的 观察血糖变化对ＳＴＺ糖尿病大鼠骨骼肌葡萄糖转运体（ＧＬＵＴ４）基因表达的影响。方法 用较小剂量的ＳＴＺ获得正常空腹血糖和空腹胰岛素水平的糖尿病大鼠,使用根皮苷纠正这种糖尿病大鼠进食后２小时的高血糖,利用Ｎｏｒｔｈｅｒｎ ｂｌｏｔ测定骨骼肌中ＧＬＵＴ４ｍＲＮＡ的含量。结果 糖尿病大鼠的骨骼肌中ＧＬＵＴ４ｍＲＮＡ的含量明显低于正常大鼠（Ｐ〈０．０１）,根皮苷治疗在不影响体重和胰岛素水平的基础上,     

高氟对大鼠心肌电生理及心电图的影响

为观察高氟对大鼠心肌电生理及心电图的影响，给两组（每组１０只）Ｗｉｓｔａｒ大鼠饲喂正常饲料，分别饮用１．５８ｍｍｏｌ／Ｌ，２．６３ｍｍｏｌ／Ｌ高氟水。；实验８个月时测定尿氟含量；描记心电图；处死动物行心肌电生理检查，同时留取血清测氟含量。结果显示：两组大鼠尿氟，血清氟含量升高；心肌细胞动作电位的ＲＰ，ＡＰＡ均降低，Ｖｍａｘ减慢，ＡＰＤ５０，ＡＰＤ９０均缩短；心电图Ｔ波振幅降低，Ｑ－Ｔ间期缩短。高氟     

锂诱发甲状腺功能减退的机制研究

对锂诱发甲状腺功能减退的机制进行了研究。结果表明５ｍｍｏｌ／Ｌ氯化锂对甲状腺细胞内ＴＳＨ刺激的ｃＡＭＰ累积有抑制作用（Ｐ＜０．００５），对ＴＳＨ引起甲状腺细胞内游离钙升高反应亦有抑制作用（Ｐ＜０．０１）。提示锂可能抑制甲状腺细胞内腺苷酸环化酶－ｃＡＭＰ和钙两种主要信号途径，导致甲状腺功能减退。     

胰淀素对大鼠胰岛素分泌的影响及其机理的探讨

目的　为研究胰淀素（ Ａｍｙｌｉｎ） 对大鼠胰岛细胞分泌胰岛素的影响和机理。方法　用放免和荧光方法分别检测经不同浓度胰淀素温育的大鼠胰岛细胞的胰岛素分泌量、细胞内 Ｃａ 《及ｃ Ａ Ｍ Ｐ 含量。结果　在胰淀素１０μｍｏｌ／ Ｌ 组中高糖刺激下的胰岛素含量、细胞内 Ｃａ 《含量，细胞内ｃ Ａ Ｍ Ｐ 含量分别为０ ．８９ ±０ ．２１ｎｇ／ ｍｌ、６３ ±１０ｎｍｏｌ／ Ｌ、２９ ．３ ±３ ．３ｐｍｏｌ／１ ×１０６ 细胞与对照组（１ ．７５ ±０ ．４２ｎｇ／ｍｌ、１３５ ±１０ｎ ｍｏｌ／ Ｌ、３６ ．３ ±７ ．４ｐｍｏｌ／ Ｌ） 比较，其中胰岛素分泌量、细胞内 Ｃａ 《含量均明显降低， Ｐ＜ ０ ．０１ ，细胞内ｃ Ａ Ｍ Ｐ 含量有减少趋势。结论　高浓度的胰淀素抑制了胰岛细胞内 Ｃａ 《升高和／ 或细胞内ｃ Ａ Ｍ Ｐ 形成，可能是胰岛素分泌减少的原因之一。     

红细胞抗高血压因子和川芎嗪对大鼠血管平滑肌cGMP含量的影响

观察红细胞抗高血压因子（ＡＨＦ）和中药川芎嗪（ＴＭＰ）对血管平滑肌细胞环一磷酸鸟苷（ｃＧＭＰ）产生的影响。方法实验用８～１０周的Ｗｉｓｔａｒ大鼠（ｎ＝６）。分离主动脉（Ａ）及肠系膜动脉（ＭＡ），其中Ａ一半去内皮，另一半保留内皮完整，将肌条分别制备成匀浆，用放射免疫分析法测定ｃＧＭＰ含量。结果ＡＨＦ（１０－５ｇ／ｍｌ）和ＴＭＰ（１０－４ｍｏｌ／Ｌ）对血管平滑肌细胞（ＶＳＭＣ）ｃＧＭＰ生成有显著刺激作用。在ＡＨＦ作用下，Ａ组有、无内皮组和ＭＡ组ｃＧＭＰ含量分别是对照组的１．２５倍，１．２６倍和１．７２倍；在ＴＭＰ作用下的实验组ｃＧＭＰ含量分别为对照组的１．６０倍，１．５０倍和１．５２倍，与对照组比较差异均有显著性（Ｐ＜０．０５或Ｐ＜０．００１）。结论ＡＨＦ和ＴＭＰ均能升高Ａ和ＭＡｃＧＭＰ水平，且ＡＨＦ对阻力血管的影响明显高于容量血管，而ＴＭＰ对两种血管的ｃＧＭＰ水平影响无明显差异，ＡＨＦ与ＴＭＰ对血管ｃＧＭＰ的增高作用似乎与内皮无关。     

乳酸酸中毒对豚鼠乳肌动作电位的影响

目的 观察在不缺氧条件下，乳酸酸中毒（ＬＡＡ）对豚鼠乳头肌动作电位（ＡＰ）的影响。方法 分别观察１５只豚鼠离体乳头肌在５ｍｍｏｌ／Ｌ、１０ｍｍｏｌ／Ｌ和１５ｍｍｏｌ／Ｌ３种浓度中毒条件下ＡＰ的变化。结果 随浓度的增加，乳头肌时程（ＡＰＤ）逐渐缩短、振幅逐渐降低，静息电位（ＲＭＰ）逐渐升高，有效不应期（ＥＲＰ）逐渐缩短。结论 ＬＡＡ对心肌ＡＰ存在有害影响，除了ｐＨ减低造成影响外，浓度升高本身对ＡＰ对     

高糖和抗生素对大鼠腹膜间皮细胞表达PAI和TGF—βmRNA的影响

为探讨腹膜硬化的发生机制，采用腹膜间皮细胞培养、纤维蛋白平板方法和Ｎｏｒｔｈｅｒｎ杂交技术观察了不同浓度葡萄糖和抗生素庆大霉素与头孢唑啉钠对大鼠腹膜间皮细胞纤溶酶原激活物抑制物（ＰＡＩ）产生和转化生长因子－β（ＴＧＦ－β）ｍＲＮＡ表达的影响。结果表明腹膜间皮细胞可表达ＰＡＩ－１ｍＲＮＡ和产生活性ＰＡＩ；培养１２小时，１１．２ｍｍｏｌ／Ｌ的高渗葡萄糖、庆大霉素和头孢唑啉钠可增强腹膜间皮细胞ＰＡＩ－１ｍＲＮＡ的表达和增加活性ＰＡＩ的分泌；培养至２４小时，１１．２ｍｍｏｌ／Ｌ的高渗葡萄糖继续诱导腹膜间皮细胞产生活性ＰＡＩ增加，庆大霉素既可以继续引起ＰＡＩ－１ｍＲＮＡ表达增加，而且还可以使腹膜间皮细胞活性ＰＡＩ产生增加。同时在培养２４小时，１１．２ｍｍｏｌ／Ｌ的高渗葡萄糖和庆大霉素与头孢唑啉钠均可引起腹膜间皮细胞ＴＧＦ－βｍＲＮＡ表达增加。结果提示：１１．２ｍｍｏｌ／Ｌ的高渗葡萄糖和庆大霉素与头孢唑啉钠可以导致间皮细胞表达ＰＡＩ和ＴＧＦ－β上调，在腹膜硬化发生机制中起着重要作用。     

血管利钠肽减弱去甲肾上腺素对心肌生长的刺激作用

本实验目的在于研究血管利钠肽（ Ｖ Ｎ Ｐ）对去甲肾上腺素（ Ｎ Ｅ）促心肌生长作用的影响,并对其机制进行探讨。分离、培养乳鼠心肌细胞,完全随机分为三组:对照组、 Ｎ Ｅ组和 Ｖ Ｎ Ｐ＋ Ｎ Ｅ组。以 Ｍ Ｔ Ｔ法和总蛋白含量测定法观察各组细胞的生长情况。进而采用放射免疫方法研究了 Ｖ Ｎ Ｐ对细胞内ｃ Ｇ Ｍ Ｐ,ｃ Ａ Ｍ Ｐ水平的影响。结果发现: Ｎ Ｅ（１０－ ７ ｍ ｏｌ／ Ｌ～１０－ ５ ｍ ｏｌ／ Ｌ）可以使培养的乳鼠心肌细胞 Ｍ Ｔ Ｔ Ｏ Ｄ值显著升高（ Ｐ＜ ０．０５ ｖｓ 对照组）,并且具有剂量依赖性。 Ｖ Ｎ Ｐ（１０－ ７ ｍ ｏｌ／ Ｌ）可以显著降低 Ｎ Ｅ（１０－ ６ ｍ ｏｌ／ Ｌ） 刺激的心肌细胞 Ｍ Ｔ Ｔ Ｏ Ｄ值和细胞内总蛋白含量（ Ｐ＜０．０５ ｖｓ Ｎ Ｅ组）。对照组和 Ｎ Ｅ组细胞内ｃ Ｇ Ｍ Ｐ,ｃ Ａ Ｍ Ｐ水平无显著差异,而 Ｖ Ｎ Ｐ（１０－ ７ ｍ ｏｌ／ Ｌ）能升高细胞内ｃ Ｇ Ｍ Ｐ水平,降低ｃ Ａ Ｍ Ｐ水平（ Ｐ＜ ０．０５ ｖｓ对照组、 Ｎ Ｅ组）。提示 Ｖ Ｎ Ｐ能减弱 Ｎ Ｅ对心肌生长的刺激作用,其机制可能与ｃ Ｇ Ｍ Ｐ,ｃ Ａ Ｍ Ｐ等信号转导分子有关。     

急性胰腺炎细胞外间质代谢的血清学研究

目的揭示急性胰腺炎（ａｃｕｔｅｐａｎｃｒｅａｔｉｔｉｓ，ＡＰ）时有关反映细胞外间质变化的血清学指标如透明质酸（ｈｙａｌｕｒｏｎｉｃａｃｉｄ，ＨＡ）、Ⅲ型前胶原肽（ＰⅢＰ）、Ⅳ型前胶原肽（ＰⅣＰ）及板层素（ｌａｍｉｎｉｎ，ＬＮ）等的变化规律及其意义．方法急性轻型胰腺炎（ｍｉｌｄａｃｕｔｅｐａｎｃｒｅａｔｉｔｉｓ，ＭＡＰ，ｎ＝１０８），急性重型胰腺炎（ｓｅｖｅｒｅａｃｕｔｅｐａｎｃｒｅａｔｉｔｉｓ，ＳＡＰ，ｎ＝２６），进行血清ＨＡ，ＰⅢＰ，ＰⅣＰ及ＬＮ含量测定，按ＡＰＡＣＨＥ及Ｒａｎｓｏｎ标准计分统计．结果和正常组比较，ＭＡＰ组ＨＡ，ＰⅢＰ，ＰⅣＰ及ＬＮ的血清含量有所升高，但无统计学差异，但ＳＡＰ组的早期，这些指标异常升高，和ＭＡＰ组间差异显著（ＨＡ，ＰⅢＰ，Ｐ＜００１；ＬＮ，Ｐ＜００５），四例死亡者ＨＡ及ＰⅢＰ升高更加明显，ＨＡ＞２００μｇ／Ｌ，ＰⅢＰ＞１６０μｇ／Ｌ），单项血清ＨＡ及ＰⅢＰ对ＳＡＰ诊断率达７８７％和７３０％，低于ＡＰＡＣＨＥⅢ标准，但是高于Ｒａｎｓｏｎ１１—６标准，且假阳性率较低，低于１０％．结论血清ＨＡ及ＰⅢＰ等含量是ＳＡＰ早期诊断及预后判定的理想指标     

人参对实验性缺血心肌细胞β受体及cAMP含量的影响

目的：观察人参对实验性缺血心肌细胞β受体及ｃ Ａ Ｍ Ｐ含量的影响。方法：对４５ 只健康成年 Ｓ Ｄ 纯种大鼠随机分为假手术对照组、单纯冠状动脉结扎组及冠状动脉结扎加人参治疗组，每组 １５ 只，应用受体放射分析法测定心肌细胞膜 β受体数量和解离常数（ Ｋｄ），放射免疫分析法测定各组心肌细胞内ｃ Ａ Ｍ Ｐ含量，在各组间进行比较。结果：结扎 Ｌ Ａ Ｄ２ 周后心肌细胞β受体的最大结合量（ Ｂｍ ａｘ，０．２７９ ｎｍ ｏｌ）较假手术组（０．０９３ ｎｍ ｏｌ）明显升高（ Ｐ ＜ ０．０５）；心肌细胞 β受体的 Ｋｄ（１２．４３１ ｎｍ ｏｌ）较假手术组（１．３１９ ｎｍ ｏｌ）明显升高（ Ｐ ＜ ０．０５）；心肌细胞内ｃ Ａ Ｍ Ｐ水平〔（１ ２９３．９６±５１９．３６） ｐｍ ｏｌ／ｇ〕亦明显高于假手术组〔（７７４．４４±２１０．５５） ｐｍ ｏｌ／ｇ〕（ Ｐ ＜ ０．０１）；经人参治疗 ２周后缺血心肌内 ｃ Ａ Ｍ Ｐ 水平〔（８０５．０２±３６２．４８） ｐｍ ｏｌ／ｇ〕明显低于单纯冠状动脉结扎组（ Ｐ ＜０．０１），与假手术组相似。结论：人参有降低缺血心肌内ｃ Ａ Ｍ Ｐ水平的作用。     

Long-term effects of a high glucose concentration in vitro on the oxidative metabolism and insulin production of isolated rat pancreatic islets

The present study was performed to clarify whether exposure in tissue culture of pancreatic islet B cells to high glucose concentrations will lead to glucose insensitivity and/or toxicity. For this purpose, isolated rat islets were maintained in tissue culture for up to 7 days in the presence of either 5.6, 11, or 56 mmol/L glucose and subsequently analyzed with regard to oxidative metabolism, insulin release, islet content of insulin, and insulin mRNA. Islets maintained at 56 mmol/L glucose showed a decreased insulin content, but no changes in insulin mRNA content when compared with control islets (cultured at 11 mmol/L glucose). In short-term incubations of the high-glucose cultured islets, the rate of insulin release at 1.67 mmol/L glucose was enhanced and could not be further stimulated by a 16.7-mmol/L glucose challenge. However, the insulin release at 16.7 mmol/L was decreased when compared with islets cultured at 11 mmol/L glucose. Islets cultured at 56 mmol/L glucose showed an increased oxygen uptake when incubated at 1.67 mmol/L glucose with no further stimulation at 16.7 mmol/L glucose. These islets also showed increased rates of glucose oxidation at incubation with 1.67 mmol/L glucose, but similar rates of oxidation at 16.7 mmol/L glucose as compared with islets cultured in 11 mmol/L glucose. Islets cultured at 5.6 mmol/L glucose showed decreased insulin release when incubated at either 1.67 mmol/L or 16.7 mmol/L glucose. The rates of glucose oxidation of these islets were also decreased at 16.7 mmol/L glucose when compared with the controls, whereas the oxygen uptake was decreased only during incubation at 1.67 mmol/L glucose. There was also a decreased content of insulin mRNA in these islets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Stimulatory short-term effects of free fatty acids on glucagon secretion at low to normal glucose concentrations

While free fatty acids (FFA) are well known as insulin secretagogues, their effects on pancreatic alpha cells have been mostly neglected. In the present study we therefore systematically analyzed the glucagon metabolism of rat pancreatic islets under the influence of FFA. Primary islets were incubated in the presence or absence of 200 micromol/L albumin-complexed palmitate or oleate at 2.8 mmol/L versus 16.7 mmol/L glucose and glucagon secretion was monitored over 8 hours. In addition to these time-course experiments, dose dependency of palmitate-induced effects was tested by a 2-hour incubation with 50 to 300 micromol/L albumin-complexed palmitate at 2.8 mmol/L and 5.6 mmol/L glucose. Apart from glucagon secretion, intracellular immunoreactive glucagon and cellular preproglucagon-mRNA (PPG-mRNA) content were determined from the remaining cell lysates. FFA, especially palmitate, induced a significant and dose-dependent increase of glucagon secretion (in average 2-fold above control) during the first 120 minutes of incubation at low to normal glucose (2.8 and 5.6 mmol/L). There was no significant glucagonotropic effect of FFA at concomitant 16.7 mmol/L glucose. Intracellular glucagon as well as cellular PPG-mRNA content were found to be dose-dependently diminished by palmitate when compared with untreated controls at 5.6 mmol/L glucose. The present analysis therefore points to a new role for FFA as a nutritient secretagogue and a modulator of alpha-cellular glucagon metabolism.     

Effects of forskolin on insulin release and cyclic AMP content in rat pancreatic islets

The effects of forskolin, a diterpene stimulator of adenylate cyclase, on cyclic AMP content and insulin release, have been studied in rat pancreatic islets. In the presence of 2.8 mM glucose, 0.3 to 30 microM forskolin gave concentration-dependent increases in cyclic AMP content to as much as seven-fold without causing any significant increase in insulin release. With 5.6 mM glucose, cyclic AMP contents were elevated by forskolin to the same extent as with 2.8 mM glucose but, under these conditions, insulin release was stimulated. 3 microM forskolin was a maximal concentration with respect to insulin release, but not for the elevation of cyclic AMP levels. Concentration-dependent increases in both insulin release and cyclic AMP content were detected over the range of 0.3 to 3 microM forskolin. The effect of forskolin to stimulate insulin release was rapid and was reversible within 15 minutes of removal of the drug. When tested with 16.7 mM glucose, forskolin potentiated both phases of stimulated release, with the greater effect upon the first phase.     

Stimulation of insulin release in isolated rat islets by GIP in physiological concentrations and its relation to islet cyclic AMP content

Summary Several insulinotropic hormones have been shown to increase the level of cyclic AMP in isolated islets. This study was performed to investigate whether gastric inhibitory polypeptide (glucose-dependent insulin-releasing polypeptide) has a similar effect, in particular at concentrations close to the physiological level in blood. Collagenase isolated rat islets were maintained for 24 h in tissue culture (medium 199) and then incubated for 30 min for measurement of insulin release and cyclic AMP content. Glucose-induced (16.7 mmol/ 1) insulin release was enhanced by gastric inhibitory polypeptide 1–100 ng/ml (0.196–19.6 nmol/l) in a dose-related fashion. The cyclic AMP content was enhanced only by 100 ng/ ml. However, when 0.1 mmol/l of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine was present, even 1 ng/ ml of gastric inhibitory polypeptide increased both cyclic AMP content and insulin release. Such a concentration of the hormone can be measured in human blood after a meal. In contrast, in freshly isolated islets no effect of the hormone on glucose-induced insulin release or cyclic AMP content could be detected for concentrations ranging from 1 to 100 ng/ml. These findings demonstrate that the hormone sensitivity of isolated islets is markedly enhanced by short-term maintenance in tissue culture. The results suggest that an increase in cyclic AMP is seen in response to gastric inhibitory polypeptide and may be causally related to the insulinotropic effect of the hormone.     

The role of cyclic AMP in the pathogenesis of glucose desensitization in rat pancreatic islets

Adenosine-3',5'-cyclic monophosphate (cyclic AMP) promotes exocytosis of insulin in pancreatic beta cells. This study was performed to investigate the role of cyclic AMP in the pathogenesis of glucose desensitization in rat pancreatic islets. In islets cultured with high glucose for 48 hours, 27 mmol/L glucose-induced insulin release was markedly impaired, while 3.3 mmol/L glucose-or arginine-induced insulin release was enhanced, indicating glucose desensitization. Islet cyclic AMP content was 190% enhanced in high glucose-culture islets for 48 hours. In islets cultured with dibutyryl-cyclic AMP (dbcAMP) or 3-isobutyl methy-xanthine (IBMX), islet insulin content or 27 mmol/L glucose-induced insulin release was deteriorated. In contrast, 3.3 mmol/L glucose- or arginine-induced insulin release was increased, which was similar to glucose-desensitized islets. Wash-out of dbc AMP for the last 24 hours of the 48-hour culture period restored impaired high glucose-induced insulin release in the same manner as wash-out of high glucose. Diazoxide, the KATP channel opener, also restored impaired high glucose-induced insulin release from dbcAMP-cultured islets. The data suggest that enhancement of cyclic AMP in high glucose-culture islets may be one of the pathogenesis of glucose desensitization.     

Phosphoenolpyruvate in rat pancreatic islets: A possible intracellular trigger of insulin release?

Summary The content of phosphoenolpyruvate (PEP) has been measured in isolated rat islets of Langerhans incubated in vitro. Islet PEP was higher in islets incubated with 16.7 mmol/l glucose than in islets incubated with zero or 2.8 mmol/l glucose. Islet PEP content was also increased in islets incubated with 5 mmol/l D-glyceraldehyde. Mannoheptulose abolished the glucose-induced rise in PEP content but not that elicited by D-glyceraldehyde. These results are consistent with a role for PEP as an intracellular mediator of glucose- and glyceraldehyde-induced insulin release. The kinetics of pyruvate kinase in extracts of rat islets were studied. The maximal extractable activity was considerably higher than known rates of glycolytic flux. The Km values were found to be 0.16 mmol/l for PEP and 0.5 mmol/l for ADP. The control of islet PEP content and the possible role of PEP in insulin release are discussed.     

高浓度葡萄糖对PDX-1表达和胰岛素分泌功能的影响

目的 探讨高浓度葡萄糖（Glu）对PDX-1表达的影响及其与胰岛素（Ins）分泌的关系。方法 分别测定SD大鼠胰岛细胞基础和Glu刺激后Ins分泌量、细胞内Ins含量、细胞内PDX-1 mRNA和蛋白的表达水平。结果 1．高糖刺激3天后，基础和Glu刺激后Ins分泌量、细胞内Ins含量及PDX-1蛋白表达水平均明显降低（P〈0．01）。2．在高糖环境下，延长培养时间可显著加强高糖对PDX-1蛋白表达的抑制作用。3．纠正高糖环境3天后可部分逆转高糖对PDX-1蛋白表达的抑制作用。结论 高浓度Glu对PDX-1蛋白表达的抑制是Glu毒性作用的机制之一，纠正高糖3天后可部分逆转高糖对PDX-1蛋白表达的抑制作用，恢复Ins分泌功能。     

Inhibition of insulin gene expression by long-term exposure of pancreatic beta cells to palmitate is dependent on the presence of a stimulatory glucose concentration

Long-term exposure of pancreatic beta cells to elevated levels of fatty acids (FAs) impairs glucose-induced insulin secretion. However, the effects of FAs on insulin gene expression are controversial. We hypothesized that FAs adversely affect insulin gene expression only in the presence of elevated glucose concentrations. To test this hypothesis, isolated rat islets were cultured for up to 1 week in the presence of 2.8 or 16.7 mmol/L glucose with or without 0.5 mmol/L palmitate. Insulin release, insulin content, and insulin mRNA levels were determined at the end of each culture period. Palmitate increased insulin release at each time point independently of the glucose concentration. In contrast, insulin content was unchanged in the presence of palmitate at 2.8 mmol/L glucose, but was markedly decreased in the presence of 0.5 mmol/L palmitate and 16.7 mmol/L glucose after 2, 3, and 7 days of culture. In the presence of a basal concentration of glucose, insulin mRNA levels were transiently increased by palmitate at 24 hours but were unchanged thereafter. In contrast, palmitate significantly inhibited the stimulatory effects of 16.7 mmol/L glucose on insulin mRNA levels after 2, 3, and 7 days. To determine whether the inhibitory effect of palmitate on glucose-stimulated insulin mRNA levels was associated with decreased insulin promoter activity, HIT-T15 cells were cultured for 24 hours in 11.1 mmol/L glucose in the presence or absence of palmitate, and insulin gene promoter activity was measured in transient transfection experiments using the insulin promoter-reporter construct INSLUC. INSLUC activity was decreased more than 2-fold after 24 hours of exposure to 0.5 mmol/L palmitate. We conclude that long-term exposure of pancreatic beta cells to palmitate decreases insulin gene expression only in the presence of elevated glucose concentrations, in part through inhibition of insulin gene promoter activity.     

高糖对成人外周血平滑肌祖细胞功能的影响

目的观察不同浓度葡萄糖对体外培养成人外周血平滑肌祖细胞（smooth muscle progenitor cells,SPCs）增殖、迁移和黏附能力的影响。方法采用密度梯度离心法从健康成人外周血获取单个核细胞,培养12d后,采用流式细胞仪对诱导扩增的SPCs进行分析鉴定并分选纯化。间接免疫荧光染色法观察SPCs培养到第28天后人平滑肌细胞特异性肌动蛋白（a-SMA）的表达情况。收集培养第12天的SPCs,随机（补充具体的随机方法？）分为5组并给予不同浓度葡萄糖干预：对照组（5．5mmol／L）,11 mmol／L组,22mmol／L组,44mmol／L组和渗透压对照组（5．5mmol／L葡萄糖加38mmol／L甘露醇）。分别用噻唑蓝（methyl thiazolyl tetrazolium,MTY）比色法．Transwell小室迁移实验以及黏附能力测定实验检测各组干预6d后SPCs增殖、迁移和黏附能力的变化。此外,培养SPCs8d,期间用22mmol／L葡萄糖分别干预0、2、4、8、d,观察各组细胞增殖、迁移和黏附能力的变化。结果与对照组相比,高糖各组均能明显促进外周血SPCs的增殖、迁移和黏附能力,其中22mmol／L葡萄糖组的影响最为显著,44mmol／L葡萄糖组的促进作用有所下降。用22mmol／L葡萄糖分别干预SPCs0、2、4、8d,其增殖、迁移和黏附能力随着作用时间延长而增强,以干预8d组最显著。结论高糖能在一定范围内增强外周血SPCs的增殖、迁移、黏附能力,随着浓度增加和时间延长,作用更明显。推测长期高血糖通过促进SPCs的功能参与受损血管过度修复．引起部分心血管疾病的发生发展。     

Effect of gastrin-releasing peptide on the secretion of mouse islet hormones in vitro

Collagenase-isolated mouse islets were incubated with gastrin-releasing peptide (GRP). At 5.6 mmol glucose/l. 10 nmol GRP/l increased the release of insulin (by 50%) and glucagon (by twofold), decreased the release of pancreatic polypeptide (by 35%), but did not significantly affect the release of somatostatin. At 16.7 mmol glucose/l, 10 nmol GRP/l increased glucagon release (by fivefold) and decreased pancreatic polypeptide release (by 46%), without significantly altering insulin and somatostatin release. GRP (200 nmol/l) did not affect insulin release by perifused mouse islets at 2.8 mmol glucose/l, but increased both first and second phase insulin release after a square wave increase in the glucose concentration to 11.1 mmol/l. At 5.6 mmol glucose/l, GRP (100 pmol/1-100 nmol/l) increased (by 50-70%) insulin release by the RINm5F clonal cell line. GRP did not affect glucose oxidation or the cyclic adenosine monophosphate content of RINm5F cells. However, the intracellular free Ca2+ concentration of RINm5F cells was rapidly and transiently increased by GRP (maximum increase of 64% about 10 s after exposure to 1 mumol GRP/l). The rise of intracellular free Ca2+ was approximately halved in the absence of extracellular Ca2+. The results suggest that GRP may contribute to the normal regulation of the endocrine pancreas. The insulin-releasing effect of GRP is mediated via increased cytosolic free Ca2+, derived both from an increased net influx of extracellular Ca2+ and from mobilization of intracellular Ca2+ stores.