Download PDF
Horm Metab Res 1989; 21(8): 405-409
DOI: 10.1055/s-2007-1009249
Originals Basic

© Georg Thieme Verlag, Stuttgart · New York

Glucose Raises Cytosolic Free Calcium in the Rat Pancreatic Islets

M. Komatsu, T. Aizawa, N. Takasu, T. Yamada
  • Department of Gerontology, Endocrinology and Metabolism, School of Medicine, Shinshu University, Matsumoto, Japan
Further Information

Publication History

1988

1988

Publication Date:
14 March 2008 (online)

Also available at
  PDF Download  Permissions and Reprints

Summary

Cytosolic free calcium ([Ca2+]i) was measured using fura 2 in the whole pancreatic islets obtained from male Wistar rats by collagenase dispersion. The pattern of change of [Ca2+]i in response to high glucose, potassium (K+) depolarization or the removal of extracellular calcium was compared with the temporal profile of insulin secretion. Twenty-nine mM glucose produced a gradual increase in [Ca2+]i with approximately 1.5 min of latency period. It remained elevated until the end of observation period (25 min) during which period the first phase of insulin secretion ceased and the second phase of secretion gradually increased. Depolarizing concentration of KCl also produced an elevation of [Ca2+]i, without detectable latency period, which lasted at a sustained level for the entire observation period (30 min). KCl caused a rapid increase of insulin secretion followed by a gradually decreasing level of secretion. Elevated [Ca2+]i and insulin secretion in response to high glucose returned to the basal level when external calcium was removed by the addition of EGTA. We conclude that high glucose and K+ depolarization raise [Ca2+]i in the pancreatic islet. However, the elevation of [Ca2+]i and insulin secretion are not always correlated in the later period of stimulation.

Key words

Pancreatic Islets - Insulin Release - Cytosolic Free Calcium

      >