Figure 14. PE excitatory response is insensitive to L‐type Ca²⁺ channel inhibition.

Aa–c, representative ST maps showing Ca²⁺ transient firing in USMCs during control conditions (a), in the presence of 10 μm phenylephrine (b) and in the presence of 10 μm phenylephrine + 1 μm nifedipine (c). Ba–d, summary data showing the effect of 1 μm nifedipine on the phenylephrine response on USMC Ca²⁺ transient frequency (a), amplitude (b), duration (c) and spatial spread (d) (c = 12, n = 4). C, representative contractile data showing the effect of 1 μm nifedipine on urethral contractions induced by phenylephrine and 90 mm extracellular K⁺. D, summary data showing the effect of 1 μm nifedipine on urethral tone (a) and contractions induced by phenylephrine (b) and 90 mm extracellular K⁺ (c) (n = 6). ns, not significant, ^** p < 0.01, ^*** p < 0.001.