Figure 4.

Ibudilast does not inhibit TRPC3 channel activity. (a) Average time courses of ATP‐stimulated changes in intracellular Ca²⁺ concentration ([Ca²⁺]_i) in TRPC3‐overexpressing HEK293 cells. Ca²⁺ release‐mediated [Ca²⁺]_i increase was first induced by ATP (100 μM) in Ca²⁺‐free external solution, and then Ca²⁺ influx‐mediated [Ca²⁺]_i increase was induced by the addition of Ca²⁺ (1.8 mM). (b) Peak changes in [Ca²⁺]_i induced by ATP in the presence of extracellular Ca²⁺ (n = 5). Cells were pretreated with or without 10 μM of ibudilast, milrinone, minoxidil, cilostazol, sildenafil, tadalafil, enoximone, and amrinone, and 3 μM of Pyr3 for 30 min before ATP stimulation. (c–e) Representative time courses (c), representative leak‐subtracted I–V relationships (d), and averaged peak current density (e, n = 5 cells per condition) of carbachol (CCh)‐induced TRPC3 currents recorded in TRPC3‐EGFP‐expressing HEK293 cells treated with or without ibudilast. Currents recorded at 100 or −100 mV of membrane potential every 2 s were plotted. Cells were treated with 100‐μM CCh 1 min after the start of recording. Ibudilast (10 μM) was applied 30 min prior to the start of and throughout the current recording. Data are shown as the mean ± SEM. *P < .05, significantly different as indicated; one‐way ANOVA with Tukey's comparison test