Abstract:
We have investigated the effect of 5-hydroxytryptamine (serotonin) (5-HT) on the membrane properties of bullfrog
taste receptor cells (TRCs) using patch-clamp technique. External application of 5-HT reversibly suppressed the voltage gated Na1 current (INa) in about half of the TRCs sampled. The magnitude of suppression of peak INa was dependent on
the holding potential of the cell. Forskolin and cyclic adenosine monophosphate (cAMP) mimicked the suppressive effect
of 5-HT on INa, but an internal protein kinase A-inhibitor potentiated INa. These results suggest that 5-HT suppresses INa of
bullfrog TRCs via protein kinase A-dependent phosphorylation, resulting in suppression of the excitability of bullfrog
TRCs. q 2000 Elsevier Science Ireland Ltd. All rights reserved.