Biphasic Regulation Of Delayed Rectifier Potassium Channels By Opioid Receptor Agonists In NG108-15 Cells

In order to understand the mechanisms of the opioid receptor mediated signal transduction, the opioid receptor agonists induced biphasic regulation of delayed rectifier potassium channels in NG108-15 cells, and the possible involvement of G protein in this regulation were studied in this work.1. The electric characteristics of K⁺, Ca²⁺ channels in NG108-15.For the convenience of using NG108-15 cells as a model system for the investigation of the mechanisms underline the coupling of opioid receptors and ion channels, the electric characteristics of potassium and calcium channels in this cell line were studied in our laboratory. A series of outward currents was evoked in NG108-15 cells by depolarizing voltage steps from -50 mV to +80 mV at holding potential of -90mV. This whole cell outward current, which was inhibited by 10mM TEA, increased with the enhance of command potential, and after reaching its steady-state, this current did not decrease with time. All these characteristics indicated that the outward current was delayed rectifier potassium current. This K⁺ current was further classified to three subtypes: rapidly activated K⁺ current without inactivation with time, slowly...