Figure 2.

Large-conductance Ca²⁺-activated K⁺ channel (BK_Ca) function is impaired in menopausal cerebral parenchymal arterioles, whereas voltage-gated K⁺ channels (K_V) remained stable. A: representative traces of the lumen diameter of endothelium-denuded parenchymal arterioles from control (top, black) and menopause (Meno) (bottom, blue) mice demonstrating impaired response to the BK_Ca inhibitor iberiotoxin (IbTox, 30 nM), observed as a smaller constriction after incubation with IbTox in the superfusing bath. Shaded areas indicate where measurements were taken. B: summary data showing lower vasoconstriction after administration of IbTox in Meno mice, suggesting that menopause impairs BK_Ca function. Data are means ± SE; N = 11 to 12 arterioles from 7 to 8 mice. *P < 0.05, 2-tailed Student’s t test. C: representative traces of the lumen diameter of endothelium-denuded pressurized arterioles before and after incubation with the K_V blocker 4-aminopyridine (4-AP). D: summary graph showing that arteriolar constriction after 1 mM and 5 mM 4-AP is not significantly different between control and Meno. Data are means ± SE; N = 9–11 arterioles from 5 different mice; 1-way ANOVA with a Bonferroni post hoc correction for multiple comparisons.