Mobilization of 45Ca from insulin-producing RINm5F cells attached to microcarriers

H. Abrahamson, P. O. Berggren, B. Hellman

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A technique was designed allowing studies of 45Ca efflux from insulin-releasing cells of a clonal cell line (RINm5F) attached to fibronectin-coated plastic beads. Supporting the existence of Ca2+-Ca2+ and Na+-Ca2+ exchange mechanisms, the efflux of 45Ca in a Ca2+-deficient perifusion medium was increased after introduction of Ca2+ and decreased after removal of Na+. The washout of radioactivity was similar to that from pancreatic islets in also being inhibited by glucose in the presence of low concentrations of extracellular Ca2+. During perifusion with a medium containing 2.56 mM Ca2+, increasing the K+ concentration resulted in an increased 45Ca efflux, a process counteracted by D-600. Also, exposure to tolbutamide resulted in a distinct stimulatory peak. Glucose was a poor stimulator of 45Ca efflux, suggesting that this sugar lacks the ability to depolarize the RINm5F cells sufficiently to induce normal opening of the voltage-dependent channels in the plasma membrane. Such a defect might well explain why the RINm5F cells do not respond to glucose with stimulation of insulin release.

Original languageEnglish
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume10
Issue number6
StatePublished - Dec 1 1984
Externally publishedYes

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Insulin
Glucose
Gallopamil
Tolbutamide
Radioactivity
Cell membranes
Islets of Langerhans
Fibronectins
Sugars
Plastics
Cells
Cell Membrane
Cell Line
Defects
Electric potential

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology

Cite this

Mobilization of 45Ca from insulin-producing RINm5F cells attached to microcarriers. / Abrahamson, H.; Berggren, P. O.; Hellman, B.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 10, No. 6, 01.12.1984.

Research output: Contribution to journalArticle

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