Taste receptor cells that discriminate between bitter stimuli

Recent studies showing that single taste bud cells express multiple bitter taste receptors have reignited a Long-standing controversy over whether sin gle gustatory receptor cells respond selectively or broadly to tastants. We examined calcium responses of rat taste receptor cells in situ to a panel of bitter compounds to determine whether individual cells distinguish betwe en bitter stimuli. Most bitter-responsive taste cells were activated by onl y one out of five compounds tested. In taste cells that responded to multip le stimuli, there were no significant associations between any two stimuli. Bitter sensation does not; appear to occur through the activation of a hom ogeneous population of broadly tuned bitter-sensitive taste cells. Instead, different bitter stimuli may activate different subpopulations of bitter-s ensitive taste cells.