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RP 49356: inhibitory effects of ionic and secretory events in rat pancreatic islets

P Lebrun1, M H Antoine, M Hermann

  • 1Laboratory of Pharmacology, Free University of Brussels, School of Medicine, Belgium.

European Journal of Pharmacology
|July 23, 1991
PubMed

Insights

RP 49356, a potassium channel opener, reduces insulin release by blocking calcium channels in pancreatic beta cells. This action also affects potassium and calcium outflow, impacting glucose-stimulated insulin secretion.

Area of Science:

  • Endocrinology
  • Pharmacology
  • Cell Physiology

Background:

  • Pancreatic beta cells regulate insulin secretion in response to glucose.
  • Calcium (Ca2+) influx is critical for glucose-stimulated insulin release.
  • Potassium (K+) channels play a role in regulating beta cell membrane potential and insulin secretion.

Purpose of the Study:

  • To investigate the mechanism of action of RP 49356 on pancreatic beta cells.
  • To determine if RP 49356 affects ion channel activity related to insulin secretion.

Main Methods:

  • Utilized 86Rubidium (86Rb) and 45Calcium (45Ca) outflow assays in isolated pancreatic islets.
  • Assessed insulin release from glucose-stimulated islets.
  • Evaluated the effects of RP 49356 in the presence and absence of glucose and Ca2+.

Main Results:

  • RP 49356 inhibited 86Rb outflow, 45Ca outflow, and insulin release from glucose-stimulated islets.
  • The inhibitory effects of RP 49356 on 86Rb outflow were abolished in glucose-free or Ca2+-free media.
  • These findings suggest RP 49356 interferes with Ca2+ influx into beta cells.

Conclusions:

  • RP 49356 may act as an antagonist of B-cell Ca2+ channels.
  • This antagonism likely reduces glucose-stimulated insulin output.
  • The drug's effect on 86Rb outflow is dependent on Ca2+ presence.

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