Sato Toshihide, Nishishita Kazuhisa, Okada Yukio, Toda Kazuo
Division of Integrative Sensory Physiology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
Cell Mol Neurobiol. 2009 Mar;29(2):243-52. doi: 10.1007/s10571-008-9317-7. Epub 2008 Oct 30.
Electrical stimulation of parasympathetic nerve (PSN) efferent fibers in the glossopharyngeal nerve induced a slow depolarizing synaptic potential (DSP) in frog taste cells under hypoxia. The objective of this study is to examine the interaction between a gustatory depolarizing receptor potential (GDRP) and a slow DSP. The amplitude of slow DSP added to a tastant-induced GDRP of 10 mV was suppressed to 60% of control slow DSPs for NaCl and acetic acid stimulations, but to 20-30% for quinine-HCl (Q-HCl) and sucrose stimulations. On the other hand, when a GDRP was induced during a prolonged slow DSP, the amplitude of GDRPs induced by 1 M NaCl and 1 M sucrose was suppressed to 50% of controls, but that by 1 mM acetic acid and 10 mM Q-HCl unchanged. It is concluded that the interaction between GDRPs and efferent-induced slow DSPs in frog taste cells under hypoxia derives from the crosstalk between a gustatory receptor current across the receptive membrane and a slow depolarizing synaptic current across the proximal subsynaptic membrane of taste cells.
在缺氧条件下，电刺激青蛙舌咽神经中的副交感神经（PSN）传出纤维会在味觉细胞中诱发缓慢去极化突触电位（DSP）。本研究的目的是检验味觉去极化受体电位（GDRP）与缓慢DSP之间的相互作用。添加到10 mV味觉诱导GDRP上的缓慢DSP的幅度，对于NaCl和醋酸刺激，被抑制到对照缓慢DSP的60%，但对于盐酸奎宁（Q-HCl）和蔗糖刺激，则被抑制到20%-30%。另一方面，当在长时间的缓慢DSP期间诱发GDRP时，1 M NaCl和1 M蔗糖诱发的GDRP幅度被抑制到对照的50%，但1 mM醋酸和10 mM Q-HCl诱发的GDRP幅度未变。得出的结论是，缺氧条件下青蛙味觉细胞中GDRP与传出神经诱导的缓慢DSP之间的相互作用源于跨感受膜的味觉受体电流与跨味觉细胞近端突触下膜的缓慢去极化突触电流之间的串扰。
