Biophysical basis of pituitary cell type-specific Ca2+ signaling-secretion coupling

Trends Endocrinol Metab. May-Jun 2005;16(4):152-9. doi: 10.1016/j.tem.2005.03.003.

Abstract

All secretory pituitary cells exhibit spontaneous and extracellular Ca2+-dependent electrical activity. Somatotrophs and lactotrophs fire plateau-bursting action potentials, which generate Ca2+ signals of sufficient amplitude to trigger hormone release. Gonadotrophs also fire action potentials spontaneously, but as single, high-amplitude spikes with limited ability to promote Ca2+ influx and secretion. However, Ca2+ mobilization in gonadotrophs transforms single spiking into plateau-bursting-type electrical activity and triggers secretion. Patch clamp analysis revealed that somatotrophs and lactotrophs, but not gonadotrophs, express BK (big)-type Ca2+-controlled K+ channels, activation of which is closely associated with voltage-gated Ca2+ influx. Conversely, pituitary gonadotrophs express SK (small)-type Ca2+-activated K+ channels that are colocalized with intracellular Ca2+ release sites. Activation of both channels is crucial for plateau-bursting-type rhythmic electrical activity and secretion.

Publication types

  • Review

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Biophysical Phenomena
  • Biophysics
  • Calcium Channels / physiology
  • Calcium Signaling / physiology*
  • Humans
  • Pituitary Gland / cytology
  • Pituitary Gland / metabolism
  • Pituitary Gland / physiology*
  • Potassium Channels / physiology
  • Sodium Channels / physiology

Substances

  • Calcium Channels
  • Potassium Channels
  • Sodium Channels