title: Amiloride-sensitive sodium currents in fungiform taste cells of rats chronically exposed to nicotine.
abstract: Many studies have demonstrated that chronic exposure to nicotine, one of the main components of tobacco smoke, has profound effects on the functionality of the mammalian taste system. However, the mechanisms underlying nicotine action are poorly understood. In particular no information is available on the chronic effect of nicotine on the functioning of taste cells, the peripheral detectors which transduce food chemicals into electrical signals to the brain. To address this issue, I studied the membrane properties of rat fungiform taste cells and evaluated the effect of long-term exposure to nicotine on the amiloride-sensitive sodium currents (ASSCs). These currents are mediated by the epithelial sodium channels (ENaC) thought to be important, at least in part, in the transduction of salty stimuli. Patch-clamp recording data indicated that ASSCs in taste cells from rats chronically treated with nicotine had a reduced amplitude compared to controls. The pharmacological and biophysical analysis of ASSCs revealed that amplitude reduction was not dependent on changes in amiloride sensitivity or channel ionic permeability, but likely derived from a decrease in the activity of ENaCs. Since these channels are considered to be sodium receptors in taste cells, my results suggest that chronic exposure to nicotine hampers the capability of these cells to respond to sodium ions. This might represent a possible cellular mechanism underlying the reduced taste sensitivity to salt typically found in smokers.
authors.affiliation: Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Sezione di Fisiologia e Neuroscienze, Università di Modena e Reggio Emilia, via G. Campi 287, 41125 Modena, Italy. Electronic address: albertino.bigiani@unimore.it.
authors.forename: A
authors.initials: A
authors.lastname: Bigiani
mesh_terms: D062646:Acid Sensing Ion Channel Blockers / Q000494:pharmacology*; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001703:Biophysics; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000145:classification / Q000187:drug effects*; D013650:Taste Buds / Q000166:cytology*
chemical_list: D062646:Acid Sensing Ion Channel Blockers; D018722:Nicotinic Agonists; D009538:Nicotine; D000584:Amiloride
keywords: ENaC; amiloride-sensitive sodium currents; nicotine; patch-clamp; smoking; taste cell