Premium
Serotonin differentially modulates the electrical properties of different subsets of taste receptor cells in bullfrog
Author(s) -
Imendra Kotapola G.,
Miyamoto Takenori,
Okada Yukio,
Toda Kazuo
Publication year - 2002
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2002.02107.x
Subject(s) - chemistry , agonist , biophysics , serotonin , 5 ht receptor , forskolin , voltage clamp , receptor , patch clamp , bullfrog , membrane potential , medicine , endocrinology , biochemistry , biology
Serotonin (5‐hydroxytryptamin, 5‐HT) is localized in taste bud cells of vertebrates. Effects of the external application of 5‐HT on the membrane currents of frog taste receptor cells (TRCs) were investigated using patch‐clamp technique in whole‐cell configuration. The 5‐HT (0.1–1 µ m ) and 5‐HT 1A receptor agonist (+/–)‐8‐OH‐2‐(D1‐ n ‐propyl‐amino)tetralin (8‐OH‐DPAT) (1–20 µ m ) inhibited both voltage‐gated sodium current ( I Na ) and voltage‐gated potassium current ( I K ) in 50% of TRCs, but potentiated I K without any significant effect on I Na in another subset of 18% of TRCs. Voltage‐gated currents in the residual TRCs were not affected by 5‐HT or 8‐OH‐DPAT. External application of 10 µ m forskolin and 300 µ m 8‐cpt cAMP [8‐(4‐chlorophenylthio)adenosine 3′:5′‐cyclic monophosphate] mimicked the inhibitory effect of 5‐HT and 8‐OH‐DPAT on I K and I Na while internal dialysis with 50 µ m protein kinase A inhibitor prevented the 5‐HT‐mediated inhibitory effects on I K and I Na in TRCs. Internal dialysis of TRCs with high Ca 2+ ‐pipette solution (1 µ m ) increased the I K in 58% of TRCs. The 5‐HT reversibly increased the [Ca 2+ ] i in 17% of TRCs when measured by Ca 2+ ‐imaging using a Ca 2+ ‐sensitive dye (fura‐2 AM). These results suggest that 5‐HT differentially modulates the voltage‐gated membrane currents in different subsets of TRCs.