spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Schmidt, J.
Right arrow Articles by Deitmer, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Schmidt, J.
Right arrow Articles by Deitmer, J.

Journal of Experimental Biology, Vol 199, Issue 2 327-335, Copyright © 1996 by Company of Biologists

JOURNAL ARTICLES

Membrane responses evoked by organic buffers in identified leech neurones

J Schmidt, C Mangold and J Deitmer

Using single-electrode current-clamp and two-electrode voltage-clamp, different identified neurones of the leech (Hirudo medicinalis L.) were shown to hyperpolarize, or to exhibit outward currents (usually >2 nA), during bath application of the organic buffers Mops, Pipes and Mes (10 mmol l-1). Tris and Hepes had little or no effect on the membrane properties of neurones when they were added to a bathing saline buffered by CO2-HCO3- at a constant pH of 7.4. Outward currents evoked by buffers obtained from two suppliers, Roth and Sigma, were not significantly different, except in the case of Pipes. Steady-state currents evoked by Pipes supplied by Roth were eightfold larger than steady-state currents evoked by Pipes from Sigma. A transient current peak always present in responses evoked by Pipes from Roth was never present in responses evoked by Pipes from Sigma. Outward currents evoked by buffers were due to a conductance increase and appeared to be carried by Cl-. In low-Cl- saline, hyperpolarizations evoked by Mops in Retzius cells were reduced. When Cl- was injected into heart motor neurones, the hyperpolarizations evoked by Mops reversed. Tetraethylammonium (TEA+) injected into heart interneurones did not block Mops-evoked hyperpolarizations. Mops-evoked outward currents in Retzius cells were partially blocked by d-tubocurarine and bicuculline methiodide, and the latter also partially blocked Mops-evoked hyperpolarizations in HE cells. Since d-tubocurarine partially blocked acetylcholine-evoked Cl- currents in Retzius cells and bicuculline methiodide partially blocked carbachol-evoked hyperpolarizations in HE cells, Mops appears to act on the cholinergic receptors of these neurones by mediating a Cl- conductance.




© The Company of Biologists Ltd 1996