Imendra K G, Fujiyama R, Miyamoto T, Okada Y, Sato T
Department of Physiology, Nagasaki University School of Dentistry, 1-7-1 Sakamoto, 852-8588, Nagasaki, Japan.
Neurosci Lett. 2000 Nov 24;294(3):151-4. doi: 10.1016/s0304-3940(00)01567-6.
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.
我们运用膜片钳技术研究了5-羟色胺（血清素）（5-HT）对牛蛙味觉感受器细胞（TRCs）膜特性的影响。在约一半所采样的TRCs中，外部施加5-HT可可逆性抑制电压门控性钠电流（I(Na)）。峰值I(Na)的抑制幅度取决于细胞的钳制电位。福斯可林和环磷酸腺苷（cAMP）模拟了5-HT对I(Na)的抑制作用，但一种蛋白激酶A内部抑制剂增强了I(Na)。这些结果表明，5-HT通过蛋白激酶A依赖性磷酸化作用抑制牛蛙TRCs的I(Na)，从而导致牛蛙TRCs兴奋性的抑制。
