Serotonin inhibits voltage-gated sodium current by cyclic adenosine monophosphate-dependent mechanism in bullfrog taste receptor cells.
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 Na(+) current (I(Na)) in about half of the TRCs sampled. The magnitude of suppression of peak I(Na) was dependent on the holding potential of the cell. Forskolin and cyclic adenosine monophosphate (cAMP) mimicked the suppressive effect of 5-HT on I(Na), but an internal protein kinase A-inhibitor potentiated I(Na). These results suggest that 5-HT suppresses I(Na) of bullfrog TRCs via protein kinase A-dependent phosphorylation, resulting in suppression of the excitability of bullfrog TRCs.
Imendra
K G
KG
Department of Physiology, Nagasaki University School of Dentistry, 1-7-1 Sakamoto, 852-8588, Nagasaki, Japan.
Fujiyama
R
R
Miyamoto
T
T
Okada
Y
Y
Sato
T
T
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology* / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D016166:Free Radical Scavengers / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects*; D011892:Rana catesbeiana; D012701:Serotonin / Q000494:pharmacology*; D015222:Sodium Channels / Q000187:drug effects* / Q000502:physiology; D013650:Taste Buds / Q000187:drug effects* / Q000502:physiology
D016166:Free Radical Scavengers; D015222:Sodium Channels; D012701:Serotonin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases