Use of a lipophilic cation for determination of membrane potential in neuroblastoma-glioma hybrid cell suspensions.

摘要: Abstract Neuroblastoma-glioma hybrid cells (NG108-15) in suspension accumulate the permeant lipophilic cation [3H]tetraphenylphosphonium (TPP+) against a concentration gradient. The steady-state level of TPP+ accumulation is about twice as great physiological media low K+ (i.e., 5 mM K+/135 Na+) than medium high 121 K+/13.5 Na+). latter manipulation depolarizes NG108-15 plasma membrane and indicates that resting potential (ΔΨ) due primarily to diffusion gradient (Kin+ → Kout+). time temperature dependent, achieving steady state 15-20 min at 37°C, linear function cell number constant). difference under various conditions has been used calculate mean (±SD) ΔΨ values -56 ± 3, -63 4, -66 mV 26, 33, respectively. Importantly, these are virtually identical those obtained by direct electrophysiological measurements made same conditions. abolished protonophore carbonylcyanide-m-chlorophenylhydrazone, whereas neurotoxic alkaloid veratridine diminishes uptake observed media. In addition, effect dependent upon presence external Na+ blocked tetrodotoxin. enhanced monensin, indicating this ionophore induces hyperpolarization appropriate Finally, ouabain essentially no on short-term experiments, suggesting Na+,K+-ATPase activity makes little contribution cells. Because many observations corroborated intracellular recording techniques, it concluded distribution can provide biochemical method for determining potentials populations cultured neuronal