Fatty acid modulation of K+ channels in taste receptor cells: gustatory cues for dietary fat.
In an attempt to determine the chemosensory cues, if any, provided by fats in the oral cavity, we have performed patch-clamp recordings on isolated rat taste receptor cells during application of free fatty acids. Cis-polyunsaturated fatty acids, when applied extracellularly, inhibit delayed-rectifying K+ channels. In a subset of cells, these fatty acids also enhance inwardly rectifying K+ currents. Saturated, monounsaturated, and trans-polyunsaturated fatty acids have no significant effect on K+ currents. These effects do not involve activation of G protein-mediated pathways, including protein kinase C and protein kinase A, lipoxygenase pathways, cyclooxygenase pathways, or cytochrome P-450 pathways, consistent with direct effects on these ion channels or closely associated proteins. The net effect of fatty acids is to prolong stimulus-induced depolarizations of taste receptor cells, and we propose the effects on K+ channels represent the mechanism by which fats are detected by receptor cells in the oral cavity.
Gilbertson
T A
TA
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808-4124, USA.
Fontenot
D T
DT
Liu
L
L
Zhang
H
H
Monroe
W T
WT
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D003463:Cues; D004041:Dietary Fats / Q000494:pharmacology*; D005227:Fatty Acids / Q000494:pharmacology*; D008297:Male; D009994:Osmolar Concentration; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000378:metabolism*; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D004041:Dietary Fats; D005227:Fatty Acids; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D016718:Arachidonic Acid