Intracellular Potassium Ion Measurements by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES)

Potassium ion (K⁺) efflux is often considered as an upstream signaling event of NLRP3 activation. The main evidence to demonstrate the importance of K⁺ efflux is that high concentration of extracellular K⁺ inhibits NLRP3 inflammasome assembly. However, the conditions used to prevent K⁺ flowing also breaks down a basic parameter of eukaryotic biology, leading to sustained membrane potential depolarization and affecting normal signal transduction in cells. Therefore, direct measurement of intracellular ion concentration can more truly reflect the role of K⁺ flow during the activation of NLRP3. In this chapter, we will provide the rationale and a method to evaluate intracellular K⁺ concentration by ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy), which helps us understand how disturbances in intracellular K⁺ level orchestrates NLRP3 inflammasome activation.