Release of LHRH is linearly related to the time integral of presynaptic Ca2+ elevation above a threshold level in bullfrog sympathetic ganglia

Neuron. 1993 Mar;10(3):465-73. doi: 10.1016/0896-6273(93)90334-n.


To study the Ca2+ dependency of luteinizing hormone-releasing hormone (LHRH) release in the bullfrog sympathetic ganglia, a method was developed to fill the preganglionic nerve terminal boutons with membrane-impermeant fura-2. We found that as stimulation frequency increased from 0.5 to 40 Hz, the peak [Ca2+]i ([Ca2+]p) and the rate of rise in [Ca2+]i increased, the decay of [Ca2+]i transients followed up to three exponentials, and release of LHRH was linearly related to integral of ([Ca2+]i--[Ca2+]t)dt. The threshold level of [Ca2+]i for LHRH release for a given set of boutons on a C cell, [Ca2+]t, was estimated by the [Ca2+]p evoked by 0.5 Hz stimulation that does not induce LHRH release.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Differential Threshold
  • Female
  • Fura-2
  • Ganglia, Sympathetic / metabolism*
  • Gonadotropin-Releasing Hormone / metabolism*
  • Male
  • Nerve Endings / metabolism
  • Osmolar Concentration
  • Rana catesbeiana
  • Synapses / metabolism*
  • Time Factors


  • Gonadotropin-Releasing Hormone
  • Calcium
  • Fura-2