Fig. 2.

Corticosterone prevents MAOi from enhancing catecholamine stimulation of excitation–contraction coupling in WT AVMs. AVMs were loaded with Ca²⁺ indicator (5 µmol/L Fluo-4 AM) and paced at 1 Hz. AVMs was pretreated with MAOi or CORTI for 5 min and followed by 6-min incubation of β-agonists (NE, EPI, or DOB). SS and Ca²⁺ were recorded for 2 min at baseline and for 6 min after agonist stimulation. The maximal SS and Ca²⁺ were reported. A, B Representative and quantification of SS% kinetics at the baselines and after stimulation with NE, EPI, or DOB in the absence or presence of MAOi. Dot plots represent the mean ± SD of the indicated number of AVMs from 6 WT mice. C Ca²⁺ transient (CaT) amplitude and decay (Tau) in response to NE, EPI, or DOB in the absence or presence MAOi. D, E Representative and quantification of SS% in response to EPI, MAOi, and CORTI cotreatment. Dot plots represent the mean ± SD of the indicated number of AVMs from 6 WT mice. F, G Representative CaT dynamics and quantification of CaT amplitude and Tau after EPI, MAOi, and CORTI cotreatment. Dot plots represent the mean ± SD of the indicated number of AVMs from 6 mice. NE = 0.1 µmol/L, EPI = 1 µmol/L, DOB = 1 µmol/L, MAOi = 5 µmol/L, and CORTI = 2 µmol/L. Data are shown as mean ± SD. p values were obtained by one-way ANOVA followed with Tukey’s test