Figure 4.

Cerebrovascular characterization: Time courses of average CBV changes (ΔCBV) elicited by i.v. infusion of 15 mg/kg acetazolamide (Diamox), comparison of cerebrovascular parameters, and correlation of CBV_bsl with vascular reactivity and reserve, respectively, for C57BL/6 (N = 10), I/LnJ (N = 5), and BALB/c (N = 7) mice. (a) Time courses of ΔCBV extracted from S1 upon injection of acetazolamide (gray vertical line) reveal increasing CBV responses in the order C57BL/6 < I/LnJ < BALB/c, respectively. Variability in CBV response was largest in I/LnJ mice. (b) Contrast agent (CA)-induced changes in baseline relaxivity ${\Delta \text{R}}_2^{*},\text{CA}$ as marker for relative CBV_bsl values in S1. C57BL/6 mice displayed the highest CBV_bsl, and BALB/c mice the lowest. (c,d) Quantification of the slope ΔCBV/Δt (c) of the CBV response elicited in S1 by the injection of acetazolamide as a measure of vascular reactivity and the mean value of individual ΔCBV_max in S1 (d) as a measure for vascular reserve. All data are given as mean across animals ± SEM. Significant differences between regions are indicated (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001). (e,f) Negative correlation between individual CBV_bsl values and slope ΔCBV/Δt (e) and ΔCBV_max (f) of the acetazolamide-induced fMRI response in S1 for the three strains. I/LnJ mice display high interindividual variability.