Figure 3.

Mild inhibition of BRV on hyperpolarization-activated cationic current (I_h) in GH₃ cells. The experiments were conducted in cells immersed in Ca²⁺-free Tyrode’s solution containing 1 µM tetrodotoxin, where the pipette was filled with a K⁺-containing solution comprising K-aspartate 130 mM, KCl 20 mM, MgCl₂ 1 mM, Na₂ATP 3 mM, Na₂GTP 0.1 mM, EGTA 0.1 mM, and HEPES 5 mM adjusted to pH 7.2 with KOH. (A) Representative I_h traces activated by a 2 s hyperpolarizing voltage pulse ranging from −40 to −120 mV (indicated in the upper part of the figure). (1): control, (2): 10 µM BRV, and (3): 10 µM BRV plus 3 µM cilobradine (Cil); (B) Summary bar graph showing the effects of BRV and BRV plus cilobradine (Cil) in hyperpolarization-activated I_h (mean ± SEM; n = 8). The current amplitude was measured at the endpoint of a 2 s hyperpolarizing pulse ranging from −40 to −120 mV. * indicates significantly different from control (p < 0.05) and † indicates signficantly different from BRV (10 mM) alone group (p < 0.05).