Luminal CCK-releasing factor stimulates CCK release from human intestinal endocrine and STC-1 cells.

  • Wang Y
  • Prpic V
  • Green G
 et al. 
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Abstract

CCK is secreted into the blood from intestinal endocrine cells following ingestion of a meal. Recently, it has been demonstrated that the ability of certain foods to stimulate CCK release is mediated by endogenously produced CCK-releasing factors. A newly discovered luminal CCK-releasing factor (LCRF) is secreted into the intestine, where it stimulates CCK secretion. However, the mechanism whereby LCRF affects intestinal epithelial cells is unknown. The current study was designed to determine whether LCRF has a direct effect on CCK cells to stimulate hormone secretion. In dispersed human intestinal mucosal cells, LCRF (5-200 nM) significantly stimulated CCK release in a concentration-dependent manner. This stimulatory effect was absent in calcium-free media and was inhibited by the L-type calcium-channel blockers diltiazem and nifedipine. To examine direct cellular effects of LCRF on CCK cells, further studies were conducted in the CCK-containing enteroendocrine cell line STC-1. As in native cells, LCRF significantly stimulated CCK release from STC-1 cells in a calcium-dependent manner. In cells loaded with a calcium-sensitive dye, LCRF stimulation produced a rapid increase in intracellular calcium. To examine the electrophysiological basis for this stimulation, whole cell recordings were made from STC-1 cells. Whole cell calcium currents were identified under basal conditions; moreover, calcium-channel activity was increased by LCRF. These studies demonstrate that 1) LCRF has a direct effect on human intestinal cells to stimulate CCK secretion, 2) stimulated hormone release is calcium dependent, and 3) LCRF activates calcium currents in CCK cells, which leads to CCK secretion.

Author-supplied keywords

  • Barium
  • Barium: pharmacology
  • Calcium
  • Calcium Channel Blockers
  • Calcium Channel Blockers: pharmacokinetics
  • Calcium Channels
  • Calcium Channels: metabolism
  • Calcium: pharmacokinetics
  • Carrier Proteins
  • Cholecystokinin
  • Cholecystokinin: metabolism
  • Cholecystokinin: secretion
  • Diltiazem
  • Diltiazem: pharmacology
  • Electrophysiology
  • Gastric Mucosa
  • Gastric Mucosa: cytology
  • Gastric Mucosa: metabolism
  • Gastric Mucosa: secretion
  • Growth Substances
  • Growth Substances: pharmacology
  • Humans
  • Intercellular Signaling Peptides and Proteins
  • Jejunum
  • Jejunum: cytology
  • Membrane Potentials
  • Membrane Potentials: drug effects
  • Membrane Potentials: physiology
  • Nifedipine
  • Nifedipine: pharmacology
  • Tumor Cells, Cultured

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Authors

  • Yu Wang

  • Vera Prpic

  • Gary M Green

  • Joseph R Reeve

  • Rodger a Liddle

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