title: Localization of K⁺, H⁺, Na⁺ and Ca²⁺ fluxes to the excretory pore in Caenorhabditis elegans: application of scanning ion-selective microelectrodes.
abstract: Although Caenorhabditis elegans is commonly used as a model organism for studies of cell biology, development and physiology, the small size of the worm has impeded measurements of ion transport by the excretory cell and hypodermis. Here, we use the scanning ion-selective microelectrode technique to measure efflux and influx of K(+), H(+), Na(+) and Ca(2+) in intact worms. Transport of ions into, or out of, immobilized worms produces small gradients in ion concentration in the unstirred layer near the surface of the worm. These gradients are readily detectable with ion-selective microelectrodes and the corresponding ion fluxes can be estimated using the Fick equation. Our data show that effluxes of K(+), H(+), Na(+) and Ca(2+) are localized to the region of the excretory pore, consistent with release of these ions from the excretory cell, and that effluxes increase after experimental preloading with Na(+), K(+) or Ca(2+). In addition, the hypodermis is a site of Na(+) influx.
authors.affiliation: Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2.
authors.forename: Aida
authors.initials: A
authors.lastname: Adlimoghaddam
authors.affiliation: Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2.
authors.forename: Dirk
authors.initials: D
authors.lastname: Weihrauch
authors.affiliation: Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1 odonnell@mcmaster.ca.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Donnell
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D017173:Caenorhabditis elegans / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport / Q000502:physiology*; D007978:Levamisole / Q000494:pharmacology; D008839:Microelectrodes; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D007978:Levamisole; D012964:Sodium; D011188:Potassium; D002118:Calcium
keywords: Excretory cell; Hypodermis; Ion-selective microelectrodes; Nematode