胰腺B细胞的胰岛素分泌是由L-氨酸衍生的氧化引起的
H H Schmidt1, T D Warner, K Ishii
1Department of Pharmacology, Northwestern University Medical School, Chicago, IL 60611.
概括
氨酸刺激胰腺B细胞释放胰岛素,由氧化 (NO) 介导. 这种NO的产生被一种特定的酶催化,这表明一种新的葡萄糖和药物诱导的胰岛素分泌途径.
科学领域:
- 生物化学 生物化学
- 内分泌学 在内分泌学.
- 细胞生物学 细胞生物学
背景情况:
- 众所周知,L-氨酸可以刺激胰腺B细胞释放胰岛素.
- 导致L-氨酸诱导胰岛素分泌的精确机制尚未完全阐明.
- 氧化 (NO) 是具有不同生理作用的信号分子.
研究的目的:
- 研究L-氨酸衍生的氧化 (NO) 在调解胰腺B细胞释放胰岛素中的作用.
- 为了确定胰腺B细胞中NO生产的酶.
- 探索NO在D-葡萄糖和托尔布塔米德刺激的胰岛素分泌中的作用.
主要方法:
- 利用三种模型系统研究L-氨酸对胰岛素释放的影响.
- 通过化学和通过瓜诺辛3',5'-单酸盐积累检测到NO的形成.
- 采用NG替代的L-氨酸类似物来抑制NO和胰岛素的释放.
- 使用抗血清对I型NO合成酶进行了蛋白质免疫块和体化学分析.
主要成果:
- 发现L-氨酸衍生的NOs可以调解由L-氨酸与D-葡萄糖和托尔布塔米德刺激的胰岛素释放.
- 在胰腺B细胞中成功检测到NO的形成.
- 用NG替代的L-氨酸类似物抑制了胰岛素和NO的释放.
- 有证据表明,NO的形成是由150kDa的NADPH-,Ca2+/calmodulin依赖型I NO合成酶催化.
结论:
- 来自L-氨酸的氧化在调解胰腺B细胞释放胰岛素方面发挥着至关重要的作用.
- 一种特定的I型NO合成酶酶催化了胰腺B细胞中NO的产生.
- 这些发现阐明了一种涉及葡萄糖和药物诱导胰岛素分泌的新信号通路.
相关概念视频
Cell Specific Gene Expression
Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with...
Stomach pH Regulation
The human body carefully regulates the internal pH of different organs to maintain homeostasis. For example, while the blood plasma maintains a neutral pH of 7, the stomach lumen has an acidic pH of 1.5 - 3.5. The low pH of stomach lumen helps kill pathogens in the food and break down complex food molecules.
The acid-secreting gastric mucosal epithelial cells (parietal cells) lining the stomach lumen maintain the low pH in the lumen. Numerous ion transporters and channels on these parietal...
The acid-secreting gastric mucosal epithelial cells (parietal cells) lining the stomach lumen maintain the low pH in the lumen. Numerous ion transporters and channels on these parietal...
Regulation of Hormone Secretion
Regulation of hormone secretion is a finely tuned orchestration driven by various types of stimuli, encompassing neural, humoral, and hormonal signals. Environmental cues instigate neural stimuli, where action potentials traverse nerve fibers to reach their designated targets. An illustrative scenario is the body's response to stress, wherein the sympathetic nervous system releases epinephrine from the adrenal glands, inducing the well-known 'fight or flight' reaction.
Humoral stimuli,...
Humoral stimuli,...
Hormones Secreted by the Stomach
Enteroendocrine cells, accounting for only 1% of stomach epithelial cells, play a significant role in digestion and are classified by their digestive hormone secretions.
Each of these hormones secreted by different enteroendocrine cells plays a unique role in digestion. Here are a few examples:
Each of these hormones secreted by different enteroendocrine cells plays a unique role in digestion. Here are a few examples:
Glucose Homeostasis: Pancreatic Islets and Insulin Secretion
The pancreatic islets comprising only 1%-2% of the volume are highly vascularized and innervated mini-organs. They contain five endocrine cell types, including β cells that secrete insulin, which is synthesized as a single polypeptide chain, preproinsulin, processed to proinsulin, and finally to insulin and C-peptide. This process is complex and regulated, involving the Golgi complex, the endoplasmic reticulum, and the secretory granules of the β cell.
Insulin and C-peptide are co-secreted in...
Insulin and C-peptide are co-secreted in...
Gastritis II: Pathophysiology
The pathophysiology of gastritis begins with the colonization of the stomach lining by Helicobacter pylori (H. pylori). This bacterium spreads mainly via the oral-oral route through saliva or shared utensils, and can also be transmitted in overcrowded or unhygienic environments through contaminated water, despite its brief survival outside the body.ColonizationOnce ingested, H. pylori enters the stomach and begins colonization by navigating through the mucus layer lining the stomach wall. It...


