Protective effect of hypothermia on brain potassium homeostasis during repetitive anoxia in Drosophila melanogaster.
Oxygen deprivation in nervous tissue depolarizes cell membranes, increasing extracellular potassium concentration ([K(+)](o)). Thus, [K(+)](o) can be used to assess neural failure. The effect of temperature (17, 23 or 29°C) on the maintenance of brain [K(+)](o) homeostasis in male Drosophila melanogaster (w1118) individuals was assessed during repeated anoxic comas induced by N(2) gas. Brain [K(+)](o) was continuously monitored using K(+)-sensitive microelectrodes while body temperature was changed using a thermoelectric cooler (TEC). Repetitive anoxia resulted in a loss of the ability to maintain [K(+)](o) baseline at 6.6±0.3 mmol l(-1). The total [K(+)](o) baseline variation (Δ[K(+)](o)) was stabilized at 17°C (-1.1±1.3 mmol l(-1)), mildly rose at 23°C (17.3±1.4 mmol l(-1)), and considerably increased at 29°C (332.7±83.0 mmol l(-1)). We conclude that (1) reperfusion patterns consisting of long anoxia, short normoxia and high cycle frequency increase disruption of brain [K(+)](o) baseline maintenance, and (2) hypothermia has a protective effect on brain K(+) homeostasis during repetitive anoxia. Male flies are suggested as a useful model for examining deleterious consequences of O(2) reperfusion with possible application for therapeutic treatment of stroke or heart attack.
Department of Biology, Queen's University, Biosciences Complex, Kingston, ON, Canada K7L 3N6. ecrodriguezp@gmail.com
Esteban C
EC
Rodríguez
R Meldrum
RM
Robertson
D000693:Anaerobiosis; D000818:Animals; D001921:Brain / Q000502:physiology; D003080:Cold Temperature; D004331:Drosophila melanogaster / Q000502:physiology*; D006706:Homeostasis; D008297:Male; D008839:Microelectrodes; D010100:Oxygen / Q000378:metabolism; D011188:Potassium / Q000502:physiology*; D020127:Recovery of Function
D011188:Potassium; D010100:Oxygen