Experimental design and Ang II infusion effects on mean arterial pressure.

A, Illustration of the experimental design used for middle-aged C57BL6J male mice including implantation of a chronic cranial window (-28 days from treatment onset) and an infusion pump and telemetry (-7 days from treatment onset). Pumps were programmed to infuse saline (baseline phase) or angiotensin II (Ang II) (treatment phase) in an intermittent manner, 1 hour every 3-4 hours or 18.4 μg/day. In-vivo 2P imaging sessions were conducted on ∼ day 20 into the treatment phase. Behavioral tests were conducted during the baseline period (Test 1) and on 25 day into the treatment phase (Test 2). This panel was created using BioRender. B, Representative raw traces of 24-hour MAP, SBP, DBP, and PP during intermittent saline (left) or Ang II infusions (right). Dashed lines correspond to the period (1 hr) when the pump is on (infusing). C, Average MAP (5 minutes) while the pump is Off or On. D, 24-hour average MAP during a 5-day saline infusion phase (Baseline) and on day 20 of treatment (Day 20). Two-way ANOVA repeated measures followed by Sidak’s multiple comparisons test (C, n = 8 BPV mice) (D, n = 12 control mice, n=8 BPV mice).

Ang II=Angiotensin II, BPV=blood pressure variability, MAP=mean arterial pressure

Effects of pulsatile BP on average 12:12 hour cardiovascular variables.

A, Summary data of two-day averages of MAP, SBP (B), DBP (C), and PP (D) during the inactive (daylight) period (left column) and the active (nighttime) period (right column). Dashed rectangles correspond to the baseline period (∼5-day saline infusion). “*” and “&” denote within group comparisons (p < 0.05 vs Baseline) for BPV and control, respectively. “#” denotes p<0.05 between groups comparisons. Two-way ANOVA repeated measures followed by Sidak’s comparison test; n = 12 control mice, n = 8 BPV mice.

BPV=blood pressure variability, DBP=diastolic blood pressure, MAP=mean arterial pressure, PP=pulse pressure, SBP=systolic blood pressure.

Ang II-induced increases in blood pressure variability (BPV).

A-B, Summary data of calculated two-day average real variability of MAP, SBP, DBP, and PP during the active period (A) and the inactive period (B). Baseline corresponds to (∼5-day saline infusion) and “*” denotes within group comparisons (p < 0.05 vs Baseline) and “#” denotes p < 0.05 between groups comparisons. Two-way ANOVA repeated measures followed by Dunnett’s comparison test; n = 11 control mice, n = 8 BPV mice.

ARV=average real variability, BPV=blood pressure variability, DBP=diastolic blood pressure, MAP= mean arterial pressure, PP=pulse pressure, SBP=systolic blood pressure.

Chronic BPV suppresses bradycardic reflex.

A, Representative raw traces of the 24-hour SBP (top) and HR (bottom) during intermittent Ang II infusions. B, Five-minute average HR when the pump is Off or On (infusing Ang II) for control and BPV groups extracted from the inactive (daytime) period. C, Twenty-four-hour average HR during ∼5-day saline infusion (Baseline), and on day 20 of treatment (Day 20) for control and BPV mice. D, Representative (5 minute) raw trace of SBP and HR (E) from one mouse while the pump is off (Low BP, grey) and then on (High BP, yellow), extracted from the inactive period. The Early and Late periods correspond to days 3-5 and days 23-25 of the treatment phase, respectively; dashed line denotes delta (Δ) between the Low and High SBP (D) and Low and High HR (E). F, Summary data of the bradycardic gain of control and BPV mice (G) during the inactive (left) and active period (right). Two-way ANOVA repeated measures followed by Sidak’s multiple comparisons test (B-C, n = 6 control mice, n= 8 BPV mice). Paired t-test and Wilcoxon (F, n = 6 control mice) (G, n = 8 BPV mice).

bpm = beats per minute, BPV = blood pressure variability, HR = heart rate, SBP = systolic blood pressure.

Enhanced myogenic responses in parenchymal arterioles of BPV mice.

A, Illustration of the experimental set-up including a portable telemetry system for blood pressure recordings simultaneously with 2P imaging recordings of parenchymal arteriole diameter. This panel was created using BioRender. B, Summary data of the average depth of acquisition below the surface of the brain where imaging was conducted. C, Summary data of the average baseline diameters of parenchymal arterioles imaged. D, Summary data of the average MAP when the infusion pump was off, low blood pressure (Low BP) range, and when the infusion pump was on, high blood pressure (High BP) range. E, Representative raw trace (from one mouse) of MAP (top) and parenchymal arteriole diameter (bottom). F, Expanded data corresponding to dashed square in (F), during the Ang II evoked BP changes. G, Representative scatter plot of MAP vs parenchymal arteriole diameter during an imaging run. H, Summary data of the slopes of the MAP-diameter linear regression, as shown in (G). I, The minimum MAP during an acquisition run vs the slope in (H); dashed lines correspond to the percent Δ change in MAP from the minimum MAP value of the run. Summary of percent Δ change in MAP from the minimum MAP shown in insert. J, Scatter plot of MAP vs delta diameter from baseline pressure (∼70 mmHg) with a pressure range 46-122 mmHg, ≤50 mmHg (K), 51-100 mmHg (L), ≥101 mmHg (M). Unpaired t-test and Mann-Whitney test (B-C, H-I, n = 13 runs/9 control mice, 11 runs/8 BPV mice). Two-way ANOVA repeated measures followed by Sidak’s multiple comparison test (D, n = 13 runs of 9 control mice, 11 runs of 8 BPV mice). Simple linear regression and “#” denotes p < 0.05 between group (J-M, n = 12 runs/9 control mice, n= 8 runs/7 BPV mice).

Art. Diameter = parenchymal arteriole diameter, BPV = blood pressure variability, MAP = mean arterial pressure.

Suppressed neurovascular responses in parenchymal arterioles of BPV during low and high blood pressure periods.

A, Illustration of the experimental setup in which a picospritzer delivered a puff of air for whisker stimulation (WS) at a rate of 10 Hz for 20 seconds. This panel was created using BioRender. B, Representative image showing the mask (outlined) used to track parenchymal arteriole diameter changes. C, Summarized data of average MAP during periods when pump is off (Low BP) and on (High BP). D, Summary data of averaged depth below the surface of the brain where imaging was conducted. E, Representative raw trace (from one mouse) of MAP (top) and parenchymal arteriole diameter (bottom) during low and high blood pressure periods; green traces correspond to the WS period response and “a” denotes the 30 seconds pre-stimulus diameter, while “b” denotes the 30 seconds post-stimulus diameter, summarized in (F). G, Normalized averaged arteriole diameter traces with the corresponding error bars as dashed lines during the WS response shown as % change from baseline (20 seconds before stimulus), 20 seconds during the stimulus (green shade), and 64 seconds post-stimulus. H, Summarized data of stimulus-induced arteriole response (green shade in G). I, Summary data of recovery time with rate of decay “ƙ” corresponding to 30 seconds post-stimulus outlined in the green dashed square in panel G. Two-way ANOVA repeated measures followed by Sidak’s multiple comparisons test (C-D, n = 7 control mice, 5 BPV mice) (F, n = 5-8 control mice, 6-7 BPV mice) and (H, n = 5-8 control mice, 6-7 BPV mice). One phase exponential decay nonlinear fit (I, n = 5-8 control mice, 6-7 BPV mice).

BPV = blood pressure variability, k = rate of decay, MAP = mean arterial pressure, WS = whisker stimulation.

Behavior and altered cognitive function of BPV mice.

A, Illustration of the novel object recognition test with a 1-hour delay between the A-A and A-B trials (top) with corresponding summarized data of mice recognition index and discriminatory index during the saline infusion period (baseline) and following 25 days of pulsatile Ang II infusion (Ang II). B, Diagram of 10-minute spontaneous Y-maze experimental preparation (top) and the summary of % alternation during baseline and 25 days of Ang II (bottom). Panels A and B were created using BioRender. C, Summary data of two-day 24-hour averages of activity throughout treatment for active and inactive periods. Baseline (∼5 day saline infusion) is marked by the dashed rectangle. D, Summary data showing 24-hour averaged activity when the pump is on or off during days 3-5 (Early) and days 23-25 (Late) of treatment. Summary of activity when the pump is on and off during the Early and Late phases of treatment for the inactive cycle (E) and active cycle (F). Paired t-test (A, n = 10 BPV mice), (B, n = 11 BPV mice). Two-way ANOVA repeated measures followed by Tukey’s comparison test (C, n = 11 control mice, 8 BPV mice) (D-F, n = 6 control mice, 8 BPV mice). “*” denotes p < 0.05 vs Baseline for control, active period. “$” and “Δ” denote p<0.05 (active vs inactive period) for control and BPV, respectively.

AU=arbitrary units, BPV=blood pressure variability