A, Representative recording of membrane potential responses at 500 μm (Vm2) from current injected at site 1 (±0.1 to 3 nA) before and during SKCa/IKCa activation with NS309 (1 μmol/L) in endothelial tube of Young. B, As in A for Old. The effect of SKCa/IKCa activation with NS309 on Conduction Amplitude (Panels C and E) and Conduction Efficiency (Panels D and F) vs. distance. Panels C and D, Young; Panels E and F, Old. NS309 reduced the amplitude and efficiency of electrical conduction across age groups with relatively greater effects in Young vs. Old (n=7 for Old, n=10 for Young). *P < 0.05 vs. NS309. Summary data are means ± S.E.