METABOLIC BASIS OF FUEL SENSING IN PANCREATIC B-CELLS

胰腺 B 细胞燃料感应的代谢基础

基本信息

批准号：
3154221
负责人：
MARTIN D. MEGLASSON
金额：
$ 9.36万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
1985
资助国家：
美国
起止时间：
1985-09-25 至 1988-08-31
项目状态：
已结题

项目摘要

Stimulation of insulin secretion by glucose involves increased sugar metabolism by Beta-cells. However, it is yet to be convincingly demonstrated that enhanced metabolism of glucose occurs during the first phase insulin secretory response due to high glucose or during stimulation of insulin secretion by neurotransmitters. Also, the metabolic processes linking increased sugar metabolism and increased Ca2+ levels initiating insulin secretion are unknown. The goal of this research is to test whether increased metabolism of glucose is an even common to both first and second phases of glucose-stimulated insulin secretion and in insulin secretion stimulated by carbachol and isoproterenol, the action of which depend on the presence of glucose. The biochemical mechanisms by which glycolysis is activated and the relationship between alteration of the energy state of Beta-cells and stimulation of insulin secretion will be determined. Beta-cells will be studied using radiation-induced (RIN) insulinomas transplantable in rats and in clonal RIN m5F and HIT cells as models of Beta-cells of normal islets. Usage and futile cycling of glucose will be determined in perfused RIN insulinomas at times selected to coincide with onset of secretion and during first and second phase insulin secretion. The method introduced by Hawkins will be used. Sites in the glycolytic pathway that may be transiently limiting will be determined by the classical approach of determining levels of glycolytic intermediates as they are influenced by secretagogues. Allosteric regulators of glycolysis (e.g., fructose-2,6-P2 and glucose-1,6-P2) and glycolytic enzymes will be determined in RIN insulinomas. Phosphofructokinase and glucose-1,6-P2 synthase, enzymes that may determine the rate of glycolysis during transition states will be purified from RIN insulinomas and from rat islets to identify isozymic forms and kinetic properties likely to determine enzyme activities in intact Beta-cells. The relationship between the cellular energy state and initiation of insulin secretion by glucose or by glyceraldehyde will be determined by measuring metabolite indicators of the energy state and by measuring parameters regulating the energy state. The effects of decreasing creatine-P + creatine or of low 02 tension on the energy state and insulin secretion will be determined. Thus essential data will be generated for developing a model of glycolysis in Beta-cells and it will be determined whether an alteration in the Beta-cell energy state is an essential event in the metabolic sequence initiated by high glucose and stimulating insulin secretion.

葡萄糖刺激胰岛素分泌涉及糖增加 β细胞的代谢。但是，这尚未令人信服证明葡萄糖的代谢增强发生在第一次由于高葡萄糖或刺激而引起的相胰岛素分泌反应神经递质的胰岛素分泌。另外，代谢过程连接增加的糖代谢和提高Ca2+水平的启动胰岛素分泌是未知的。这项研究的目的是测试葡萄糖的代谢增加是否是首先和葡萄糖刺激的胰岛素分泌和胰岛素的第二阶段 Carbachol和Isroperenol刺激的分泌物，其作用取决于葡萄糖的存在。生化机制糖酵解被激活，并且改变 β细胞的能量状态和胰岛素分泌的刺激将是决定。将使用辐射诱导的（RIN）研究β细胞可在大鼠和克隆RIN M5F中移植的胰岛素瘤，并击中细胞为正常胰岛的β细胞模型。葡萄糖的使用和徒劳将在被选为灌注的RIN胰岛素瘤中确定与分泌的发作以及第一阶段和第二阶段胰岛素一致分泌。将使用霍金斯引入的方法。站点可能瞬时限制的糖酵解途径将由确定糖酵解中间体水平的经典方法他们受到秘密的影响。糖酵解的变构调节剂（例如，果糖-2,6-P2和葡萄糖1,6-P2）和糖酵解酶是在RIN胰岛素瘤中确定。磷酸果糖激酶和葡萄糖1,6-P2 合成酶，可能确定糖酵解速率的酶过渡状态将从RIN胰参加和大鼠胰岛纯化识别可能确定的同学形式和动力学特性完整β细胞中的酶活性。之间的关系细胞能态和葡萄糖或胰岛素分泌的开始甘油醛将通过测量代谢物指标来确定能量状态和通过测量调节能量状态的参数。这减少肌酸P +肌酸或低02张力的影响将确定能量状态和胰岛素分泌。因此，基本数据将生成用于在β细胞中开发糖酵解模型的生成将确定Beta细胞能状态的改变是否为高葡萄糖和刺激胰岛素分泌。