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. 2021 Jun 23;34(11):1227–1235. doi: 10.1093/ajh/hpab098

Figure 4.

Figure 4.

Pressure-induced vasoconstriction (PIC) responses of MCA segments following transfection with EGFP or EGFP–mβENaC. (a,b) Intraluminal diameters of MCA segments transfected with EGFP control (a) or EGFP–mβENaC (b) in response to stepwise increases in intraluminal pressure under active (Ca2+-containing, ●) and under passive (Ca2+-free, ○) conditions. The passive responses (Ca2+-free) in EGFP vs. EGFP–mβENaC were compared using two-way repeated measures ANOVA, which showed a main effect of intraluminal pressure (P < 0.0001), but no main effect of expression construct (P = 0.336) or interaction of intraluminal pressure and construct (P = 0.274) on the response. (c) Calculated myogenic tone of isolated MCAs following transfection with EGFP (○) or EGFP–mβENaC (●). Two-way repeated measures ANOVA showed an effect of intraluminal pressure (P < 0.0001) and EGFP–mβENaC expression (P = 0.0001) and an interaction between genotype and intraluminal pressure (P < 0.0451) on intraluminal pressure vs. % myogenic tone. Sidak’s multiple comparison post hoc test showed a significant effect of expression of EGFP–mβENaC on myogenic tone at 45 (P = 0.0170), 60 (P = 0.0156), 75 (P = 0.0006), and 90 (P = 0.0124) mm Hg intraluminal pressure values. (d) Pressure and myogenic tone relationship was linearized by plotting pressure log vs. tone to obtain the slope or estimate of PIC sensitivity. (e) Slope of the relationship between log of intraluminal pressure vs. myogenic tone of the MCA following transfection with EGFP or EGFP–mβENaC. Individual data points are shown. PIC sensitivity was significantly increased in MCA segments following transfection with EGFP–mβENaC compared to that of EGFP (P = 0.0272, unpaired two-tailed t test). Data are presented as mean ± SEM, n = 5 in each group. *Significantly different from control at P < 0.05. †Significantly different from control at P < 0.001. EGFP, enhanced green fluorescent protein; mβENaC, mouse beta-epithelial Na+ channel; MCA, middle cerebral artery; ANOVA, analysis of variance; SEM, standard error of the mean.