Actions of glutamate and ivermectin on the pharyngeal muscle of Ascaridia galli: A comparative study with Caenorhabditis elegans
Actions of glutamate and ivermectin on the pharyngeal muscle of Ascaridia galli: A comparative study with Caenorhabditis elegans
The actions of glutamate and ivermectin were examined in the pharynx of Ascaridia galli and the results compared with those on the pharynx of Caenorhabditis elegans. In both preparations glutamate elicits a depolarization and inhibition of pharyngeal pumping, but the response of the pharynx of A. galli was much less than for C. elegans. This may be either because the pharyngeal membrane potential of the former is closely linked to the equilibrium potential for chloride ions (ECl) while that of C. elegans is independent of ECl, or that there is a lower density of glutamate receptors on the pharyngeal muscle of A. galli compared with C. elegans. The maximum depolarization to glutamate of the pharyngeal muscle was 4.5±0.8 mV in A. galli while it was >25 mV in C. elegans. Picrotoxin was a weak antagonist of the glutamate response in both species. Flufenamic acid, pentobarbitone and flurazepam had no significant effect on either preparation at concentrations up to 100 ?M. Three glutamate receptor agonists, ibotenate, kainate and quisqualate were all more potent than glutamate on the A. galli pharyngeal muscle. In contrast, only ibotenate was more potent than glutamate in C. elegans pharynx, the other two agonists being approximately 20 times less potent. The potency of ivermectin differed markedly between the two species, being approximately three orders of magnitude less potent on the pharynx of A. galli compared with C. elegans. This study demonstrates clear differences between the properties of the pharyngeal muscle of the two species and shows that care must be taken when extrapolating data from free-living to parasitic species of nematode.
ascaridia galli, ivermectin, caenorhabitis elegans, electrophysiology, pharynx
395-402
Holden-Dye, Linda
8032bf60-5db6-40cb-b71c-ddda9d212c8e
Walker, Robert J.
9368ac2d-f1e9-4bd9-a4b4-4a161c4aa140
1 April 2006
Holden-Dye, Linda
8032bf60-5db6-40cb-b71c-ddda9d212c8e
Walker, Robert J.
9368ac2d-f1e9-4bd9-a4b4-4a161c4aa140
Holden-Dye, Linda and Walker, Robert J.
(2006)
Actions of glutamate and ivermectin on the pharyngeal muscle of Ascaridia galli: A comparative study with Caenorhabditis elegans.
International Journal for Parasitology, 36 (4), .
(doi:10.1016/j.ijpara.2005.11.006).
Abstract
The actions of glutamate and ivermectin were examined in the pharynx of Ascaridia galli and the results compared with those on the pharynx of Caenorhabditis elegans. In both preparations glutamate elicits a depolarization and inhibition of pharyngeal pumping, but the response of the pharynx of A. galli was much less than for C. elegans. This may be either because the pharyngeal membrane potential of the former is closely linked to the equilibrium potential for chloride ions (ECl) while that of C. elegans is independent of ECl, or that there is a lower density of glutamate receptors on the pharyngeal muscle of A. galli compared with C. elegans. The maximum depolarization to glutamate of the pharyngeal muscle was 4.5±0.8 mV in A. galli while it was >25 mV in C. elegans. Picrotoxin was a weak antagonist of the glutamate response in both species. Flufenamic acid, pentobarbitone and flurazepam had no significant effect on either preparation at concentrations up to 100 ?M. Three glutamate receptor agonists, ibotenate, kainate and quisqualate were all more potent than glutamate on the A. galli pharyngeal muscle. In contrast, only ibotenate was more potent than glutamate in C. elegans pharynx, the other two agonists being approximately 20 times less potent. The potency of ivermectin differed markedly between the two species, being approximately three orders of magnitude less potent on the pharynx of A. galli compared with C. elegans. This study demonstrates clear differences between the properties of the pharyngeal muscle of the two species and shows that care must be taken when extrapolating data from free-living to parasitic species of nematode.
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Published date: 1 April 2006
Keywords:
ascaridia galli, ivermectin, caenorhabitis elegans, electrophysiology, pharynx
Organisations:
Biological Sciences
Identifiers
Local EPrints ID: 40530
URI: http://eprints.soton.ac.uk/id/eprint/40530
ISSN: 0020-7519
PURE UUID: c0782492-5009-4eab-81cb-4d8fdd3cfdd7
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Date deposited: 03 Jul 2006
Last modified: 16 Mar 2024 04:37
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