Membrane-initiated Ca(2+) signals are reshaped during propagation to subcellular regions

Biophys J. 2001 Jul;81(1):57-65. doi: 10.1016/S0006-3495(01)75679-2.

Abstract

An important aspect of Ca(2+) signaling is the ability of cells to generate intracellular Ca(2+) waves. In this study we have analyzed the cellular and subcellular kinetics of Ca(2+) waves in a neuroendocrine transducer cell, the melanotrope of Xenopus laevis, using the ratiometric Ca(2+) probe indo-1 and video-rate UV confocal laser-scanning microscopy. The purpose of the present study was to investigate how local Ca(2+) changes contribute to a global Ca(2+) signal; subsequently we quantified how a Ca(2+) wave is kinetically reshaped as it is propagated through the cell. The combined kinetics of all subcellular Ca(2+) signals determined the shape of the total cellular Ca(2+) signal, but each subcellular contribution to the cellular signal was not constant in time. Near the plasma membrane, [Ca(2+)](i) increased and decreased rapidly, processes that can be described by a linear and exponential function, respectively. In more central parts of the cell slower kinetics were observed that were best described by a Hill equation. This reshaping of the Ca(2+) wave was modeled with an equation derived from a low-pass RC filter. We propose that the differences in spatial kinetics of the Ca(2+) signal serves as a mechanism by which the same cellular Ca(2+) signal carries different regulatory information to different subcellular regions of the cell, thus evoking differential cellular responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Signaling*
  • Calibration
  • Electrochemistry
  • Erythrocytes / cytology
  • Erythrocytes / metabolism*
  • Imaging, Three-Dimensional
  • Intracellular Fluid / metabolism*
  • Kinetics
  • Models, Biological
  • Xenopus laevis

Substances

  • Calcium