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Ion Channels and Excitable Membranes

開催日 2014/9/11
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Detecting the Monovalent Cation Concentrations at the Vicinity of the Plasma Membrane

  • P1-001
  • Wan Hsuan Hsu:1 Chien-Yuan Pan:1 
  • 1:Dept of Life science, National Taiwan University, Taipei, Taiwan 

Cells utilize different ions to support various physiological activities. Ca2+ participates in neurotransmitters release and muscle contraction. Na+ concentration is the highest in the body fluid; thus plays an important role in regulating the blood pressure and maintaining the balance of blood circulation. The increase in the serum Na+ concentration elevates the blood pressure. In conjugation with K+, Na+ helps the transmission of nerve impulses. K+ is the most abundant ion inside the cell. K+ regulates many cell activities like membrane permeability, growth, etc; most importantly, K+ determines the resting membrane potential to modulate the neuron excitability. We are interested in understanding the concentrations of Na+ and K+ at both sides of the plasma membrane. We first used the Na+ specific fluorescence indicators to investigate the change of intracellular Na+ concentration ([Na+]i). The basal [Na+]i was 16.5 ± 1.6 mM and elevated by 1.5 fold in cultured neurons stimulated by 10 µM glutamate. To investigate the K+ efflux at the plasma surface, we modified a K+-aptamer on the silicon nanowire field-effect transistor. The data shows the functionalized device responded to different alkali ions with various affinities; K+ (Kd = 7.9 ± 0.4 mM) > Cs+ (Kd = 12.1 ± 0.5 mM) > Na+ (Kd = 24.8 ± 4.1 mM) > Li+ (Kd = 189.0 ± 44.5 mM). We will anchor cell onto the silicon nanowire to investigate the K+ concentration at the membrane surface. These measurements of the ion concentration at the micro-environment will provide detail information in understanding the neuron-neuron interactions.

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