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

A, Schematic of the experimental design for middle-aged C57BL/6J male mice, including implantation of a chronic cranial window (−28 days from treatment onset) and an infusion pump with telemetry (−7 days from treatment onset). Infusion pumps were programmed for intermittent delivery of saline (baseline phase) or angiotensin II (Ang II) (treatment phase) at a rate of 18.4 μg/day, administered in 1-hour intervals every 3-4 hours. In-vivo two-photon (2P) imaging sessions were performed approximately 20 days into the treatment phase. Behavioral tests were conducted during the baseline period (Test 1) and 25 days into the treatment phase (Test 2). This panel was created using BioRender/v89f171. B, Representative raw traces depicting minute-to-minute, 24-hour MAP, SBP, DBP, PP, and Activity levels during intermittent saline infusions (left) and Ang II infusions (right). Dashed lines indicate periods of active infusion (1 hr) or when the pump is on. C, Average MAP, SBP, DBP, and PP (5 minutes) measured during infusion Off versus On conditions. D, 24-hour average MAP, SBP, DBP, and PP during a 5-day saline infusion phase (Baseline) and on Day 20 of Ang II treatment. Two-way ANOVA repeated measures followed by Sidak’s multiple comparisons test (C, n = 8 BPV mice) (D, n = 13 control mice, n = 8 BPV mice).

Ang II=Angiotensin II, BPV=blood pressure variability, DBP=diastolic blood pressure MAP=mean arterial pressure, PP=pulse pressure, SBP=systolic blood 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 indicate 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 = 13 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 = 13 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 24-hour SBP (top) and HR (bottom) during intermittent Ang II infusions. B, Five-minute average HR when the infusion pump is Off or On (actively infusing Ang II) for control and BPV groups, extracted from the inactive (daytime) period. C, Twenty-four-hour average HR during the baseline period (∼5-day saline infusion), and on day 20 of treatment (Day 20) for control and BPV mice. D, Scatter plot of SBP and HR during Ang II infusion (100 minutes: 20 minutes before and after the 60-minute pulse) in the inactive period for control and BPV mice (E). Linear trend lines for data shown in the insert. Early and Late periods correspond to days 3-5 and days 23-25 of the treatment phase, respectively. F, Scatter plot of SBP and HR during the active period in controls and in BPV mice (G). Two-way ANOVA repeated measures followed by Sidak’s multiple comparisons test (B-C, n = 6 control mice, n = 8 BPV mice). Simple linear regression and “#” denotes p < 0.05 within group (D, F, n = 6 control mice) (E, G, n = 8 BPV mice).

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

Norepinephrine infusion effects.

A, Representative raw trace of minute-to-minute 24hr HR (top) and SBP (bottom). The green-shaded region indicates the 1-hour period when the pump is actively infusing NE (45 µg/kg/min). This panel was created using BioRender/m19t088. B, Summary data of two-day average MAP during the baseline phase (Dashed rectangle, ∼5-day saline infusion) and over 20 days of treatment. C, Summary data of calculated two-day ARV of SBP (left) and CV of SBP (right). D, Scatter plot of SBP and HR during NE infusion (100-minute window: 20 minutes before and after the 60-minute pulse) in the inactive (left) and active (right) periods, with linear trend lines shown in the insert. Early and Late periods correspond to days 3-5 and days 16-20 of the treatment phase. “*” and “#” denote within group comparisons (p < 0.05 vs Baseline) for Ang II- and NE-infused mice, respectively. “&” and “Δ” denotes between group comparisons (p<0.05 vs control group) for Ang II- and NE-infused mice, respectively. Two-way ANOVA repeated measures followed by Sidak’s multiple comparisons test (B-C, n = 6 mice). Simple linear regression (D, n = 3 mice).

Ang II=Angiotensin II, bpm = beats per minute, HR = heart rate, NE = norepinephrine, SBP = systolic blood pressure.

Enhanced myogenic responses in parenchymal arterioles of BPV mice.

A, Schematic of the experimental set-up, including a portable telemetry system for continuous blood pressure recordings alongside simultaneous 2P imaging of parenchymal arteriole diameter. This panel was created using BioRender/c21h358. B, Summary data for the average imaging depth below the brain surface. C, Summary data for the average baseline diameters of imaged parenchymal arterioles. D, Summary data of the average MAP recorded under infusion pump off conditions (low blood pressure, Low BP) and infusion pump on conditions (high blood pressure, High BP). E, Representative raw trace (from a single mouse) showing MAP (top) and parenchymal arteriole diameter (bottom) over time. F, Expanded data corresponding to dashed region in (E), highlighting Ang II-evoked BP changes. G, Representative scatter plot and linear regression of MAP vs parenchymal arteriole diameter during an imaging session. H, Summary data of MAP-diameter linear regression slopes. I, Relationship between minimum MAP recorded during an imaging run and the slope shown in (H); dashed lines indicate the percent Δ change in MAP relative to its minimum value. The insert provides a summary of percent Δ change in MAP from the minimum MAP. J, Scatter plot of MAP vs changes in arteriole diameter from baseline pressure (∼70 mmHg), spanning a pressure range 46-122 mmHg. Data subsets extracted from (J): (K) MAP ≤51 mmHg (orange dashed region), (L) MAP 51-100 mmHg (green dashed region), and (M) MAP ≥101 mmHg (blue dashed region). N, Illustration of the proposed leftward shift (and narrower plateau) in cerebral autoregulatory curve induced by chronic BPV. Unpaired t-test and Mann-Whitney test (B-C, H-I, n = 10 runs/8 control mice, n = 11 runs/8 BPV mice). Two-way ANOVA repeated measures followed by Sidak’s multiple comparison test (D, n = 10 runs/8 control mice, n = 11 runs/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).

BPV = blood pressure variability, MAP = mean arterial pressure

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

A, Schematic of the experimental setup in which a picospritzer delivered a puff of air for whisker stimulation (WS) at 10 Hz for 20 seconds. B, Representative image showing the mask (outlined) used to track changes in parenchymal arteriole diameter. Panels A and B were created using BioRender/b34x028. C, Summarized data of average MAP recorded during low blood pressure (Low BP; pump off) and high blood pressure (High BP; pump on) conditions. D, Summary data of the average imaging depth below the brain surface. E, Representative raw trace (from a single mouse) showing MAP (top) and parenchymal arteriole diameter (bottom) during low and high blood pressure. Dashed green squares indicate WS response, with “a” denoting the 30-second pre-stimulus diameter and “b” denoting the 30-second post-stimulus diameter, summarized in (F). G, Normalized averaged arteriole diameter traces with corresponding error bars (dashed lines) during the WS response, shown as % change from baseline (20 seconds before stimulus), during the 20-second stimulus (green shaded region), and 64 seconds post-stimulus (green dashed square). H, Summarized data of stimulus-induced arteriole responses (green shaded region in G). I, Summary data of recovery time, with rate of decay (ƙ) corresponding to 30-second post-stimulus period outlined in the green dashed square in (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, n = 6-7 BPV mice) and (H, n = 5-8 control mice, n = 6-7 BPV mice). One phase exponential decay nonlinear fit (I, n = 5-8 control mice, n = 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, Schematic of the novel object recognition test with a 1-hour delay between the A-A and A-B trials (top), accompanied by summarized recognition and discriminatory index data for mice 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 setup (top) and the summary of % alternation and distance traveled during baseline and after 25 days of Ang II treatment (bottom). C, Summary data of two-day, 24-hour activity averages throughout treatment during active and inactive periods, with the Baseline phase (∼5-day saline infusion) marked by the dashed rectangle. D, Summary data of 24-hour averaged activity recorded when the infusion pump was on vs off during Early (days 3-5) and Late (days 23-25) treatment phases. (E) Summary of activity when the pump is on vs off during the Early and Late phases of treatment for the inactive cycle. (F) Summary of activity when the pump is on vs off during the Early and Late phases of treatment for the active cycle. 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 = 13 control mice, n = 8 BPV mice) (D-F, n = 6 control mice, n = 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