Fig. 7From: N-alkylisatin-based microtubule destabilizers bind to the colchicine site on tubulin and retain efficacy in drug resistant acute lymphoblastic leukemia cell lines with less in vitro neurotoxicityCytotoxic drugs differentially affect the electrophysiological properties of SH-SY5Y RA differentiated cells. a Top traces depict whole cell voltage clamp recordings of endogenous currents from representative naïve SH-SY5Y cells (Ctr, purple), retinoic acid differentiated (RA, black), and RA-differentiated cells treated with 5 nM HMB-isatin (red), 5 nM vinblastine (VBL, blue) and 5 nM vincristine (VCR, green). Currents were elicited by 25 ms step depolarizations to 0 mV from a Vh: -80 mV preceded by a 100 ms –120 mV pre-pulse (inset under Ctr). Scale bar: 1 nA. The insets below RA, HMB-isatin and VBL show voltage traces in response to current injection (50–100 pA, ∆10 pA, inset under VCR) that elicited action potentials from their respective Vh. Scale bars are: 10 mV and 100 ms. b and c Voltage dependent parameters of inward sodium currents in all groups obtained from IV stimulation protocols from −60 to 60 mV (∆10 mV, Vh: −80 mV). IVs from representative cells are shown in the inset on the right. b Slope and activation half voltage. c Right: maximal conductance (Gmax) and inward current density estimated from the ratio of peak current amplitude observed at 0 mV to the cell membrane capacitance (pA/pF). Ctr: non differentiated; RA: Retinoic acid differentiated; HMB-isatin: 5,7-dibromo-N-(p-hydroxymethylbenzyl)isatin treated RA cells; VBL: vinblastine treated RA cells; VCR: vincristine treated RA cells (drugs were applied overnight at 10 nM). Mean ± SEM from n = 5–24 cells per condition. Unpaired t-test compares RA against all other groups with a 95% confidence interval. Data are presented as means ± SEMs (n represents the number of individual recordings). A two-tailed, paired t-test was applied to compare current density between retinoic acid differentiated cells to the other experimental groups. Data presented is compiled from 3 independent experiments involving cell differentiation and drug treatmentBack to article page