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Pflügers Archiv

, Volume 452, Issue 4, pp 435–443 | Cite as

Effects of intracellular pH and Ca2+ on the activity of stretch-sensitive cation channels in leech neurons

  • C. Barsanti
  • M. Pellegrini
  • D. Ricci
  • M. PellegrinoEmail author
Ion Channels, Transporters

Abstract

The effects of intracellular pH and calcium on the activity of the leech mechanosensitive cation channels have been studied. These channels exhibited two activity modes denoted as spike-like (SL) and multiconductance (MC). In the absence of mechanical stimulation, acidification of the intracellular side of membrane patches from 7.2 to 6.2 reversibly increased the mean channel open time as well as the opening frequency in the SL mode. Channels in MC mode were activated by a pHi reduction from 7.2 to 6.2, but were inhibited at pHi 5.5. Unlike MC mode, SL mode was strongly activated by intracellular Ca2+. Fura-2 imaging experiments showed that intracellular calcium was induced to increase by hypotonic cell swelling. The major component of this response did not require extracellular calcium. A component of the swelling-induced calcium response was sensitive to blockers of stretch-sensitive cation channels. The results indicate that the two activity modes of mechanosensitive channels of leech neurons respond differently to changes of intracellular pH and calcium. The sensitivity of the channel to micromolar concentrations of internal free calcium, along with its permeability to this ion, is consistent with a role in the amplification of mechanically induced Ca2+ signals in leech neurons.

Keywords

Mechanosensitive ion channels Patch clamp Single-channel recording Calcium imaging TRP channels 

Notes

Acknowledgements

The authors wish to thank Paolo Orsini who developed part of the calcium imaging software and Francesco Montanari for making the filter wheel device.

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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • C. Barsanti
    • 1
  • M. Pellegrini
    • 2
  • D. Ricci
    • 1
  • M. Pellegrino
    • 1
    Email author
  1. 1.Dipartimento di Fisiologia e Biochimica “G. Moruzzi”Università di PisaPisaItaly
  2. 2.Scuola Normale SuperiorePisaItaly

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