Paul J. Fadel, PhD
Research Interests
Neural cardiovascular control at rest and during exercise
Research Description
Fadel's laboratory's research focus entails the investigation of neural cardiovascular control at rest and during exercise in humans with a specific emphasis on the sympathetic branch of the autonomic nervous system. Ongoing studies involve assessing sympathetic responses during various physiological manipulations including isometric and aerobic forms of exercise, lower body negative pressure to simulate the effect of gravity when one stands up, and infusions of pharmacological agents. Studies are performed in normal healthy subjects as well as in patients with various pathophysiological conditions such as heart failure and hypertension.
Fadel's laboratory obtains direct measures of sympathetic neural firing using the technique of microneurography. This measurement allows for the assessment of moment-to-moment as well as long term changes in sympathetic nerve activity. Also, with the application of partial autospectral and time series analyses to muscle sympathetic neurograms, investigation into the central origin(s) and pattern(s) of sympathetic discharge in humans has begun. Fadel's current research focus is on the neural mechanisms that contribute to exercise-induced sympathoexcitation as well as the peripheral modulators of sympathetically-mediated vasoconstriction in contracting skeletal muscle with a particular emphasis on the potential roles of free radicals and changes in nitric oxide signaling in altering these responses.
Considering the continually increasing population of elderly individuals, the future direction of Fadel's lab will be to begin to examine age related alterations in neural cardiovascular control during exercise. Research in this area has been limited and is extremely important considering that an exaggerated blood pressure response to exercise increases the risk for mortality in otherwise healthy adults.
Professional Background
- Obtained BS in physical education, Brooklyn College.
- Obtained MS in clinical exercise physiology, Northeastern University, Boston, Mass.
- Obtained PhD in biomedical sciences, University of North Texas Health Science Center.
- Completed postdoctoral training at University of Texas Southwestern Medical Center.
- Received New Investigator Award, University of Texas Southwestern Allied Health Sciences School.
- Received American Physiological Society, Neural Control & Autonomic Regulation Section Michael J. Brody Young Investigator Award.
- Received American Physiological Society Research Career Enhancement Award.
- Received American Physiological Society, Caroline tum Suden/Frances A. Hellebrandt Professional Opportunity Award.
Selected Publications
Fadel PJ. Neural control of the circulation during exercise in health and disease. Front Physiol. Aug 26;4:224, 2013.
Fairfax ST, Padilla J, Vianna LC, Holwerda SH, Davis MJ, Fadel PJ. Influence of spontaneously occurring bursts of muscle sympathetic nerve activity on conduit artery diameter. Am J Physiol Heart Circ Physiol. Sep;305(6):H867-74, 2013.
Greaney JL, Schwartz CE, Edwards DG, Fadel PJ, Farquhar WB. The neural interaction between the arterial baroreflex and muscle metaboreflex is preserved in older men. Exp Physiol. Oct;98(10):1422-31, 2013.
Mikus CR, Boyle LJ, Borengasser SJ, Oberlin DJ, Naples SP, Fletcher J, Meers GM, Ruebel M, Laughlin MH, Dellsperger KC, Fadel PJ, Thyfault JP. Simvastatin impairs exercise training adaptations. J Am Coll Cardiol. S0735-1097(13)01403-4, 2013.
Fairfax ST, Holwerda SW, Credeur DP, Zuidema MY, Medley JH, Dyke II PC, Wray DW, Davis MJ, Fadel PJ. The role of α-adrenergic receptors in mediating beat-by-beat sympathetic vascular transduction in the forearm of resting man. J Physiol, 15;591(Pt 14):3637-49, 2013.
Jenkins NT, Padilla J, Boyle LJ, Credeur DP, Laughlin MH, Fadel PJ. Disturbed Blood Flow Acutely Induces Activation and Apoptosis of the Human Vascular Endothelium. Hypertension. 61(3):615-21, 2013.
Fairfax ST, Padilla J, Vianna LC, Davis MJ, Fadel PJ. Spontaneous Bursts of Muscle Sympathetic Nerve Activity Decrease Leg Vascular Conductance in Resting Humans. AJP (Heart Circ Physiol), 304(5):H759-66, 2013.
Adlan AM, Lip GY, Fadel PJ, Fisher JP. Sympathetic nerve activity during non-sustained Fadel, Paul ventricular tachycardia in chronic heart failure. Int J Cardiol. 10:165(2):e15-7, 2012.
Deo SH, Fisher JP, Vianna LC, Kim A, Chockalingam AC, Zimmerman MC, Zucker IH, Fadel PJ. Statin therapy lowers muscle sympathetic nerve activity and oxidative stress in patients with heart failure. AJP (Heart Circ Physiol), 303(3):H377-85, 2012.
Fadel PJ, Farias III M, Gallagher KM, Wang Z, Thomas GD. Oxidative stress and enhanced sympathetic vasoconstriction in contracting muscles of nitrate-tolerant rats and humans. J Physiol, 590(Pt 2):395-407, 2012.
Fisher JP, Kim A, Hartwich D, Fadel PJ. New insights into the effects of age and sex on arterial baroreflex function at rest and during dynamic exercise in humans. Auton Neurosci. 24;172:13-22, 2012.
Vianna LC, Hart EC, Fairfax ST, Charkoudian N, Joyner MJ, Fadel PJ. Influence of age and sex on the pressor response following a spontaneous burst of muscle sympathetic nerve activity. AJP (Heart Circ Physiol), 302(11):H2419-27, 2012.
Kim A, Deo SH, Fisher JP, Fadel PJ. Effect of sex and ovarian hormones on carotid baroreflex resetting and function during dynamic exercise in humans. J Appl Physiol, 112(8):1361-71, 2012.
Fadel PJ, Raven PB. Human investigations into the arterial and cardiopulmonary baroreflexes during exercise. Exp Physiol, 97(1):39-50, 2012.
Padilla J, Simmons GH, Fadel PJ, Laughlin MH, Joyner MJ, Casey DP. Impact of aging on conduit artery retrograde and oscillatory shear at rest and during exercise: Role of nitric oxide. Hypertension, 57(3):484-9, 2011.
Kim A, Deo SH, Vianna LC, Balanos GM, Hartwich D, Fisher JP, Fadel PJ. Sex differences in carotid baroreflex control of arterial blood pressure in humans: Relative contribution of cardiac output and total vascular conductance. AJP (Heart Circ Physiol), 301(6):H2454-65, 2011.
Akimoto T, Sugawara J, Ichikawa D, Terada N, Fadel PJ, Ogoh S. Enhanced open-loop but not closed-loop cardiac baroreflex sensitivity during orthostatic stress in humans. AJP (Regul Integr Comp Physiol), 301(5):R1591-8, 2011.
Fadel PJ.,Is greater resting sympathetic nerve activity better for hypertension? Perhaps for the arterial baroreflex.,J Physiol. 2011 Aug 1;589(Pt 15):3687-8. No abstract available. PMID: 21807609
Padilla J, Simmons GH, Vianna LC, Davis MJ, Laughlin MH, Fadel PJ., Brachial artery vasodilation during prolonged lower-limb exercise: Role of shear rate.,Exp Physiol. 2011 Jul 22. [Epub ahead of print]PMID: 21784788
Mikus CR, Fairfax ST, Libla JL, Boyle LJ, Vianna LC, Oberlin DJ, Uptergrove GM, Deo SH, Kim A, Kanaley JA, Fadel PJ, Thyfault JP.,Seven days of aerobic exercise training improves conduit artery blood flow following glucose ingestion in patients with type 2 diabetes., J Appl Physiol. 2011 Jul 7. [Epub ahead of print]PMID: 21737826
Padilla J, Simmons GH, Fadel PJ, Laughlin MH, Joyner MJ, Casey DP., Impact of aging on conduit artery retrograde and oscillatory shear at rest and during exercise: role of nitric oxide. ,Hypertension. 2011 Mar;57(3):484-9. Epub 2011 Jan 24.PMID: 21263118
Simmons GH, Padilla J, Young CN, Wong BJ, Lang JA, Davis MJ, Laughlin MH, Fadel PJ., Increased brachial artery retrograde shear rate at exercise onset is abolished during prolonged cycling: role of thermoregulatory vasodilation.,J Appl Physiol. 2011 Feb;110(2):389-97. Epub 2010 Nov 18.PMID: 21088203
Fisher JP, Kim A, Young CN, Fadel PJ., Carotid baroreflex control of arterial blood pressure at rest and during dynamic exercise in aging humans., Am J Physiol Regul Integr Comp Physiol. 2010 Nov;299(5):R1241-7. Epub 2010 Sep 8.PMID: 20826707
Young CN, Deo SH, Chaudhary K, Thyfault JP, Fadel PJ.,Insulin enhances the gain of arterial baroreflex control of muscle sympathetic nerve activity in humans., J Physiol. 2010 Sep 15;588(Pt 18):3593-603. Epub 2010 Jul 19.PMID:20643774
Young CN, Deo SH, Padilla J, Laughlin MH, Fadel PJ., Pro-atherogenic shear rate patterns in the femoral artery of healthy older adults., Atherosclerosis. 2010 Aug;211(2):390-2. Epub 2010 Mar 16. No abstract available. PMID: 20394928
Padilla J, Young CN, Simmons GH, Deo SH, Newcomer SC, Sullivan JP, Laughlin MH, Fadel PJ., Increased muscle sympathetic nerve activity acutely alters conduit artery shear rate patterns., Am J Physiol Heart Circ Physiol. 2010 Apr;298(4):H1128-35. Epub 2010 Feb 12.PMID: 20154260
