The prior R29 award underwrote the first independent investigations, helped establish our research, and led to innovative findings on baroreflex control with aging and habitual exercise. We fully addressed the aims of the prior award by devising and perfecting our baroreflex methodology and by demonstrating the importance of vagal neural control in the age-related decrement and activity-related maintenance of baroreflex function. In addition, we found an important reciprocal relation between decreased cardiac vagal function and elevated vascular sympathetic outflow with age. A reciprocity suggests cardiovagal function determines the resting levels of and baroreflex control of vascular sympathetic outflow. Since high sympathetic outflow relates to cardiovascular risk, this is germane to aging in the presence of coronary disease. If increased vagal control reduces sympathetic outflow, strategies that increase cardiovagal baroreflex function would be doubly beneficial. We seek renewed funding to: determine if reciprocity between baroreflex cardiac vagal and vascular sympathetic function is evident in older trained individuals, and if it can be modified acutely in young and older individuals; determine the effects of coronary disease on the reciprocity between vagal and sympathetic baroreflex control; and, determine the effects of 6 months aerobic exercise training on vagal and sympathetic baroreflex function in older individuals and in coronary patients. Based on our previous work, we hypothesize that healthy older individuals with high vagal capacity (i.e.,masters athletes) will have sympathetic outflow and control comparable to young individuals. Further, this reciprocal relation will allow manipulation of sympathetic outflow and control by enhancing (via drug or exercise) or depressing (via drug) vagal tone. Based on preliminary findings, we hypothesize greater vascular stiffness in coronary patients will relate to higher resting sympathetic outflow, but that increasing cardiovagal function with exercise will decrease sympathetic outflow in both coronary patients and healthy older individuals. This work will inform the striking incongruence between increased resting sympathetic outflow and apparently maintained sympathetic baroreflex gain with age. Moreover, if increased vagal function results in reduced sympathetic outflow, exercise should result in an autonomic profile more favorable to cardiovascular health. We seek renewed funding to examine fully sympatho-vagal interactions with age and disease and prospectively assess effects of exercise.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
3R01AG014376-06A1S1
Application #
6800895
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Dutta, Chhanda
Project Start
1997-06-01
Project End
2008-06-30
Budget Start
2003-09-30
Budget End
2004-06-30
Support Year
6
Fiscal Year
2003
Total Cost
$144,579
Indirect Cost
Name
Hebrew Rehabilitation Center for Aged
Department
Type
DUNS #
030832075
City
Boston
State
MA
Country
United States
Zip Code
02131
Callegaro, Carine C; Taylor, J Andrew (2012) Age-related effects of vagotonic atropine on cardiovagal baroreflex gain. Neurobiol Aging 33:368-74
Ler, A S H; Cohen, M A; Taylor, J A (2010) A planar elliptical model of cardio-vagal hysteresis. Physiol Meas 31:857-73
Tan, Can Ozan; Taylor, J Andrew (2010) Does respiratory sinus arrhythmia serve a buffering role for diastolic pressure fluctuations? Am J Physiol Heart Circ Physiol 298:H1492-8
Picard, Glen; Tan, Can Ozan; Zafonte, Ross et al. (2009) Incongruous changes in heart period and heart rate variability with vagotonic atropine: implications for rehabilitation medicine. PM R 1:820-6
Studinger, Péter; Goldstein, Richard; Taylor, J Andrew (2009) Age- and fitness-related alterations in vascular sympathetic control. J Physiol 587:2049-57
Tan, Can Ozan; Taylor, J Andrew; Ler, Albert S H et al. (2009) Detection of multifiber neuronal firings: a mixture separation model applied to sympathetic recordings. IEEE Trans Biomed Eng 56:147-58
Tan, Can Ozan; Cohen, Michael A; Eckberg, Dwain L et al. (2009) Fractal properties of human heart period variability: physiological and methodological implications. J Physiol 587:3929-41
Deley, Gaelle; Picard, Glen; Taylor, J Andrew (2009) Arterial baroreflex control of cardiac vagal outflow in older individuals can be enhanced by aerobic exercise training. Hypertension 53:826-32
Lee, Kichang; Picard, Glen; Beske, Stacy D et al. (2008) Effects of fitness and age on the response to vagotonic atropine. Auton Neurosci 139:60-7