Figure 4. Effects of pharmacological agents on NaCl stress-related membrane potential and steady-state and transient K⁺ fluxes.

(A) Membrane potential (MP). P. euphratica cells were untreated (control) or treated with 200 mM NaCl supplemented with or without 200 µM ATP for 24 h in the presence and absence of suramin (300 µM), PPADS (300 µM), or the H-G system (50 mM glucose and 100 units/mL hexokinase). Then, cells were incubated with the MP-sensitive fluorescent probe, DiBAC₄(3). Values (white font) represent the mean±SD based on quantifications from at least 50–60 individual cells in three independent experiments. Different letters (a, b, c) denote significant differences between treatments (P<0.01). (B) Steady-state K⁺ fluxes. K⁺ fluxes across the PM were measured with SIET. Bars represent the mean of 15–18 individual cells and whiskers represent the standard error of the mean. Different letters (a, b, c) denote significant differences between treatments (P<0.05). (C) Transient K⁺ fluxes in response to NaCl (200 mM) or NaCl (200 mM) plus ATP (200 µM) in the presence and absence of suramin, PPADS, or H-G system. Each point represents the mean of six individual cells measured in three independent experiments. (D) Peak and mean values for transient K⁺ fluxes before (-) and after (+) the addition of NaCl or NaCl plus ATP. Bars represent the mean of six individual cells and whiskers represent the standard error of the mean. N.S. = no significant difference.