TY - GEN
T1 - Hemodynamics changes with acute carotid baroreceptor field stimulation are age-dependent in normotensive rats
AU - Kouchaki, Zahra
AU - Butlin, Mark
AU - Avolio, Alberto P.
PY - 2015/11/4
Y1 - 2015/11/4
N2 - Carotid baroreceptor stimulation can treat resistant hypertension with possible effects on the vasculature beyond the decrease in arterial pressure. This study aims to characterize age-dependency of vascular hemodynamics changes with unilateral field stimulation of carotid baroreceptors in normotensive rats to infer underlying hemodynamic mechanisms. Anesthetized Wistar-Kyoto rats divided into two groups (young: n=10, 13-33 weeks; old: n=6, 52-58 weeks) were instrumented to measure heart rate (HR) and mean arterial pressure (MAP), and flow in the abdominal aorta and renal artery. Measures of aortic and renal artery stiffness and resistance were calculated. Baroreceptor stimulation caused a consistent reduction in MAP, HR, pulse pressure and aortic pulse wave velocity. In young rats reduced MAP (77±10 to 64±13 mmHg, p<0.001) was concomitant with reduced mean aortic (40±15 to 32±11 ml/min, p<0.05) and renal flow (3.0±1.6 2.2±1.1 ml/min, p<0.001). However, in old rats reduced MAP (76±14 to 64±10 mmHg, p<0.05) occurred with a reduced aortic resistance (1.8±0.9 to 1.6±0.9 mmHg.min/ml, p<0.05), renal artery resistance (17.4±2.4 to 16.5±2.3 mmHg.min/ml, p<0.05) and mean renal flow (4.5±1.2 to 4.0±1.1 ml/min, p<0.05). This was consistent with reduced characteristic impedance in older rats in both the aorta (0.17±0.08 to 0.13±0.08 mmHg.min/ml, p<0.05) and renal artery (4.97±1.16 to 3.97±1.08 mmHg.min/ml, p<0.05). Stimulation caused a leftward shift in renal impedance phase frequency spectrum in both age groups indicating changes in wave reflection from the renal bed. Findings show that the reduction in MAP due to carotid barostimulation is associated with different hemodynamic mechanisms that depend on age.
AB - Carotid baroreceptor stimulation can treat resistant hypertension with possible effects on the vasculature beyond the decrease in arterial pressure. This study aims to characterize age-dependency of vascular hemodynamics changes with unilateral field stimulation of carotid baroreceptors in normotensive rats to infer underlying hemodynamic mechanisms. Anesthetized Wistar-Kyoto rats divided into two groups (young: n=10, 13-33 weeks; old: n=6, 52-58 weeks) were instrumented to measure heart rate (HR) and mean arterial pressure (MAP), and flow in the abdominal aorta and renal artery. Measures of aortic and renal artery stiffness and resistance were calculated. Baroreceptor stimulation caused a consistent reduction in MAP, HR, pulse pressure and aortic pulse wave velocity. In young rats reduced MAP (77±10 to 64±13 mmHg, p<0.001) was concomitant with reduced mean aortic (40±15 to 32±11 ml/min, p<0.05) and renal flow (3.0±1.6 2.2±1.1 ml/min, p<0.001). However, in old rats reduced MAP (76±14 to 64±10 mmHg, p<0.05) occurred with a reduced aortic resistance (1.8±0.9 to 1.6±0.9 mmHg.min/ml, p<0.05), renal artery resistance (17.4±2.4 to 16.5±2.3 mmHg.min/ml, p<0.05) and mean renal flow (4.5±1.2 to 4.0±1.1 ml/min, p<0.05). This was consistent with reduced characteristic impedance in older rats in both the aorta (0.17±0.08 to 0.13±0.08 mmHg.min/ml, p<0.05) and renal artery (4.97±1.16 to 3.97±1.08 mmHg.min/ml, p<0.05). Stimulation caused a leftward shift in renal impedance phase frequency spectrum in both age groups indicating changes in wave reflection from the renal bed. Findings show that the reduction in MAP due to carotid barostimulation is associated with different hemodynamic mechanisms that depend on age.
UR - http://www.scopus.com/inward/record.url?scp=84953217066&partnerID=8YFLogxK
U2 - 10.1109/EMBC.2015.7318790
DO - 10.1109/EMBC.2015.7318790
M3 - Conference proceeding contribution
C2 - 26736690
AN - SCOPUS:84953217066
T3 - IEEE Engineering in Medicine and Biology Society Conference Proceedings
SP - 2051
EP - 2054
BT - 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2015
PB - Institute of Electrical and Electronics Engineers (IEEE)
CY - New York
T2 - 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2015
Y2 - 25 August 2015 through 29 August 2015
ER -