Ryanodine receptor-operated activation of TRP-like channels can trigger critical Ca2+ signaling events in pancreatic beta-cells

FASEB J. 2005 Feb;19(2):301-3. doi: 10.1096/fj.04-2621fje. Epub 2004 Nov 30.

Abstract

There is little information available concerning the link between the ryanodine (RY) receptors and the downstream Ca(2+) signaling events in beta-cells. In fura-2 loaded INS-1E cells, activation of RY receptors by 9-methyl 5,7-dibromoeudistomin D (MBED) caused a rapid rise of [Ca(2+)]i followed by a plateau and repetitive [Ca(2+)]i spikes on the plateau. The [Ca(2+)]i plateau was abolished by omission of extracellular Ca(2+) and by SKF 96365. In the presence of SKF 96365, MBED produced a transient increase of [Ca(2+)]i, which was abolished by thapsigargin. Activation of RY receptors caused Ca(2+) entry even when the ER Ca(2+) pool was depleted by thapsigargin. The [Ca(2+)]i plateau was not inhibited by nimodipine or ruthenium red, but was inhibited by membrane depolarization, La(3+), Gd(3+), niflumic acid, and 2-aminoethoxydiphenyl borate, agents that inhibit the transient receptor potential channels. The [Ca(2+)]i spikes were inhibited by nimodipine and ryanodine, indicating that they were due to Ca(2+) influx through the voltage-gated Ca(2+) channels and Ca(2+)-induced Ca(2+) release (CICR). Activation of RY receptors depolarized membrane potential as measured by patch clamp. Thus, activation of RY receptors leads to coherent changes in Ca(2+) signaling, which includes activation of TRP-like channels, membrane depolarization, activation of the voltage-gated Ca(2+) channels and CICR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels / metabolism*
  • Calcium Signaling / physiology*
  • Cell Line, Tumor
  • Insulinoma / chemistry
  • Insulinoma / metabolism
  • Insulinoma / pathology
  • Islets of Langerhans / chemistry
  • Islets of Langerhans / metabolism
  • Islets of Langerhans / pathology
  • Male
  • Pancreatic Neoplasms / chemistry
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology
  • Patch-Clamp Techniques / methods
  • Rats
  • Rats, Wistar
  • Ryanodine Receptor Calcium Release Channel / metabolism*

Substances

  • Calcium Channels
  • Ryanodine Receptor Calcium Release Channel