Dynamic measurements of [K+]i in cardiac differentiated P19 cells with a quantum dots (QD) potassium nanobiosensor, K‐QD (1097.5)

We reported the first dynamic measurements of [K+]i in intact differentiated P19 cells using a K‐QD nanobiosensor. K‐QD was synthesized by conjugating a 15‐crown‐5 K+ receptor to water soluble QD emitted at 630 nm. In Vitro spectral characterization of K‐QD confirms the sensitivity and specificity of K‐QD that is operated within the physiological K+ ranged from 4 to 130 mM. Differentiation of P19 cells was induced with 1% DMSO. A photon counting fluorescence microscope system with 405 nm excitation and 630nm emission was used to perform experiments with K‐QD loaded in the differentiated P19 cells using cation liposome. In four studies, 10‐8M to 10‐5M cumulative dose responses of [K+]i of each of the following 10 agents were determined. They were (i) quinidine, TEA and glibenclamide for the inhibition of the efflux of K+; (ii) bumetanide, ouabain, and acetylstrophanthidin for the inhibition of the influx of K+; (iii) levocromokalim and NS1619 for the activation of the K+ efflux; and (iv) nifedipine and verapamil for the inhibition of the calcium channels. Five experiments were performed per agent. The predictable and consistent responses induced by all these agents suggest that the application of K‐QD to determine the [K+]i responses in the cardiac differentiated P19 cells could be a robust platform for K+ channel compound screening, drug discovery and toxicology.Grant Funding Source: NIDDK R44‐DK084600