SEROTONIN INHIBITS CALCIUM-ACTIVATED K-CELLS( CURRENT IN RAT TASTE RECEPTOR)

LITTLE is definitively known of the identity or actions of neurotransm itters utilized within mammalian taste buds. Serotonin has been immuno cytochemically localized to taste cells of several species but its phy siological actions are unknown. Using whole-cell patch clamp recording s on dissociated posterior rat taste cells, data are presented to sugg est that exogenously applied serotonin inhibits a calcium-activated po tassium current by up to 50%. This current, best visualized at depolar ized holding potentials, is both apamin-and charybdotoxin-sensitive. A pproximately 60% of the tested taste cells were serotonin sensitive. T his inhibition was mimicked by N-(3-trifluoromethylphenyl)piperazine ( TFMPP), a general serotonin receptor agonist, by 8-hydroxy-dipropylami notetralin (8-OH-DPAT), a selective 5-HT1A receptor agonist, but not b y phenylbiguanide, a 5-HT3 receptor agonist. These are the first data to establish a physiological effect of serotonin on mammalian taste ce lls.