Synergistic Insulin Release Induced by Glucose and Carbachol is not associated with an Increase in Cytoplasmic Free Calcium Levels

Endocrine Journal

JUNICHIRO KASHIWADA²  KATSUHIRO TAMURA²  KEIICHIRO TANIGAWA¹  YUZURU KATO¹ 

[1] Internal Medicine, Shimane Medical University;Departments of Surgery, Shimane Medical University

关键词: Insulin release;    Ca2+;    Fura-2;    Phosphoinositide breakdown;   

DOI  :  10.1507/endocrj.41.677

学科分类：内分泌与代谢学

来源: Japan Endocrine Society

【 摘 要 】

References(24)Synergistic insulin release is observed in combination with muscarinic agonist and glucose. In order to define the role of changes in the cytoplasmic free Ca2+level ([Ca2+] i), the effect of combination with carbachol and glucose on both phosphoinositide breakdown in rat pancreatic islets and [Ca2+] i dynamics in single fura 2-loaded B-cells was investigated. When the islets were prelabeled with myo-[2-3H] inositol, phosphoinositide breakdown was obtained and inositol trisphosphate levels were increased in the presence of carbachol (0.5 mM). Inositol trisphosphate levels induced by carbachol were further increased by co-stimulation with 16.7 mM glucose.[Ca2+] i in single-B-cells was increased by 16.7 mM glucose. A prompt, transient rise in [Ca2+] i was induced by carbachol. However, carbachol failed to augment the [Ca2+] i response in the presence of 16.7 mM glucose. These data suggest that a synergistic release of insulin occurs without an amplification of [Ca2+] i regardless of an increase in inositol trisphosphate.

【 授权许可】

Unknown