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Chem Senses

Title:		Ca2+ stabilizes the membrane potential of moth olfactory receptor neurons at rest and is essential for their fast repolarization
Author(s):		Pezier A; Acquistapace A; Renou M; Rospars JP; Lucas P;
Address:		"UMR1272 Physiologie de l'Insecte: Signalisation et Communication, INRA, Route de St Cyr, 78026 Versailles Cedex, France"
Journal Title:		Chem Senses
Year:		2007
Volume:		20070130
Issue:		4
Page Number:		305 - 317
DOI:		10.1093/chemse/bjl059
ISSN/ISBN:		0379-864X (Print) 0379-864X (Linking)
Abstract:		"The role of Ca(2+) in insect olfactory transduction was studied in the moth Spodoptera littoralis. Single sensillum recordings were made to investigate in vivo the role of sensillar Ca(2+) on the electrophysiological properties of sex pheromone responsive olfactory receptor neurons (ORNs). Lowering the sensillar Ca(2+) concentration to 2 x 10(-8) M increased ORN spontaneous firing activity and induced long bursts of action potentials (APs) superimposed on spontaneous negative deflections of the transepithelial potential. We inferred that Ca(2+) stabilizes the membrane potential of ORNs, keeping the spontaneous firing activity at a low and regular level. Neither the amplitude and kinetics of the rising phase of sensillar potentials (SPs) recorded in response to pheromone stimuli nor the AP generation during stimulation depended on the extracellular Ca(2+) concentration. Thus, extracellular Ca(2+) is not absolutely necessary for ORN response. Partial inhibition of responses with a calmodulin antagonist, W-7, also indicates that intracellular Ca(2+) contributes to the ORN response and suggests that Ca(2+) release from internal stores is involved. In 2 x 10(-8) M Ca(2+), the repolarization of the SP was delayed when compared with higher Ca(2+) concentrations. Therefore, in contrast to depolarization, ORN repolarization depends on extracellular Ca(2+). Ca(2+)-gated K(+) channels identified from cultured ORNs with whole-cell recordings are good candidates to mediate ORN repolarization"
Keywords:		"Animals Calcium/*physiology Cells, Cultured *Evoked Potentials Male Olfactory Receptor Neurons/drug effects/*physiology Patch-Clamp Techniques Pheromones/pharmacology Spodoptera/*physiology;"
Notes:		"MedlinePezier, Adeline Acquistapace, Adrien Renou, Michel Rospars, Jean-Pierre Lucas, Philippe eng Research Support, Non-U.S. Gov't England 2007/02/03 Chem Senses. 2007 May; 32(4):305-17. doi: 10.1093/chemse/bjl059. Epub 2007 Jan 30"