title: Cold hardening modulates K+ homeostasis in the brain of Drosophila melanogaster during chill coma.
abstract: Environmental temperature is one of the most important abiotic factors affecting insect behaviour; virtually all physiological processes, including those which regulate nervous system function, are affected. At both low and high temperature extremes insects enter a coma during which individuals do not display behaviour and are unresponsive to stimulation. We investigated neurophysiological correlates of chill and hyperthermic coma in Drosophila melanogaster. Coma resulting from anoxia causes a profound loss of K(+) homeostasis characterized by a surge in extracellular K(+) concentration ([K(+)](o)) in the brain. We recorded [K(+)](o) in the brain during exposure to both low and high temperatures and observed a similar surge in [K(+)](o) which recovered to baseline concentrations following return to room temperature. We also found that rapid cold hardening (RCH) using a cold pretreatment (4°C for 2h; 2h recovery at room temperature) increased the peak brain [K(+)](o) reached during a subsequent chill coma and increased the rates of accumulation and clearance of [K(+)](o). We conclude that RCH preserves K(+) homeostasis in the fly brain during exposure to cold by reducing the temperature sensitivity of the rates of homeostatic processes.
authors.affiliation: Department of Biology, Queen's University, Kingston, ON, Canada K7L 3N6. gary.ab.armstrong@gmail.com
authors.forename: Gary A B
authors.initials: GA
authors.lastname: Armstrong
authors.forename: Esteban C
authors.initials: EC
authors.lastname: Rodríguez
authors.forename: R
authors.initials: R
authors.lastname: Meldrum Robertson
mesh_terms: D000064:Acclimatization; D000818:Animals; D001921:Brain / Q000378:metabolism*; D003080:Cold Temperature; D003128:Coma / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism*; D006706:Homeostasis; D000860:Hypoxia / Q000378:metabolism; D008297:Male; D011188:Potassium / Q000378:metabolism*
chemical_list: D011188:Potassium