Dr. Philip Millar

Research Interests:

A salient feature of almost all cardiovascular diseases, and there associated risk factors, is the activation of the sympathetic nervous system. The consequences of this action are profound and impact blood pressure control, insulin sensitivity, arrhythmogenesis, and risk of sudden cardiac death. The primary aim of my research is to better understand the mechanisms that control, and functional consequences of, sympathetic outflow at rest and during stressors in humans with and without cardiovascular disease. To uncover these mechanisms I employ direct intraneural recordings of postganglionic sympathetic traffic, studying both multi- and single-fibre preparations. A major focus of my current work is directed at uncovering the ability of sympathetic fibres to be selectively and differentially controlled. A second focus is on testing novel and clinically relevant exercise and non-exercise interventions designed to reduce sympathetic over-activation.

Projects in Progress:

• Effects of ischemic preconditioning on neural and hemodynamic responses to muscle metaboreflex activation
• Role of the sympathetic nervous system in mediating reductions in blood pressure following acute dietary nitrate supplementation with beetroot juice
• Hemodynamic and neural responses to one-legged cycling in endurance athletes
• Autonomic and vascular function late following successful repair of coarctation of the aorta by surgical and endovascular methods

Facilities/Unique Equipment:

662C-4 Nerve Traffic Analyzer (Single- and multi-unit microneurography)
Finometer MIDI (Beat-to-beat hemodynamics)
Doppler ultrasound (Cardiac and vascular imaging)
Applanation tonometer (Pulse-wave velocity)
Electrocardiography
Lower body pressure chamber
Exercise equipment (arm cycle ergometer, handgrip, stationary bicycles)

Funding:

NSERC Discovery Grant � Millar (PI) 2015-2019, Evidence for differential control of muscle sympathetic fibres in humans
Canadian Foundation for Innovation (CFI) 2015 – PI

Links:

Departmental Faculty Page

Students:

Anthony Incognito, MSc student (2014-present)
Connor Doherty, Undergraduate research project (2015-16)
Karam Notay, Undergraduate research project (2015-16)
Jordan Lee, Undergraduate student (2015)

Publications (since 2010):

1. Notarius CF, Millar PJ, Floras JS. Muscle sympathetic activity in resting and exercising humans with and without heart failure. Appl Physiol Nutr Metab. (Epub ahead of print August 2015).
2. Millar PJ, Murai H, Floras JS. Paradoxical muscle sympathetic reflex activation in human heart failure. Circulation 2015; 131(5):459-468.
3. Notarius CF, Millar PJ, Murai H, Morris BL, Marzolini S, Oh P, Floras JS. Divergent muscle sympathetic responses to dynamic leg exercise in heart failure and age-matched healthy subjects. J Physiol (Lond) 2015; 593(3):715-722.
4. Millar PJ, Goodman JM. Exercise as medicine: Role in the management of primary hypertension. Appl Physiol Nutr Metab 2014; 39(7):856-858.
5. Carlson DJ, Dieberg G, Hess NC, Millar PJ, Smart NA. Isometric exercise training for blood pressure management: A systematic review and meta-analysis. Mayo Clin Proc 2014; 89(3): 327-334.
6. Millar PJ, Floras JS. Statins and the autonomic nervous system. Clin Sci 2014; 126(6): 401-415.
7. Millar PJ, McGowan CL, Cornelissen VA, Araujo CG, Swaine IL. Evidence for the role of isometric exercise training to reduce resting blood pressure: Potential mechanisms and future directions. Sports Med 2014; 44(3): 345-356.
8. Notarius CF, Millar PJ, Murai H, Morris BL, Floras JS. Inverse relationship between muscle sympathetic nerve activity during exercise and peak oxygen uptake in subjects with and without heart failure. J Am Coll Cardiol 2014; 63(6): 605-606.
9. Millar PJ, O�Donnell E. Alpha males: Muscle sympathetic discharge on beat-to-beat forearm vascular conductance. J Physiol 2013; 591(18): 4375-4376.
10. Millar PJ, Murai H, Morris BL, Floras JS. Microneurographic evidence in healthy middle-aged humans for a sympathoexcitatory reflex activated by atrial pressure. Am J Physiol Heart Circ Physiol 2013; 305(6): 931-938.
11. Currie KD, Rosen LM, Millar PJ, McKelvie RS, MacDonald MJ. Heart rate recovery and heart rate variability are unchanged in patients with coronary artery disease following 12-weeks of high-intensity interval and moderate-intensity endurance exercise training. Appl Physiol Nutr Metab 2013; 38(6): 644-650.
12. Badrov MB, Bartol CL, DiBartolomeo MA, Millar PJ, McNevin NH, McGowan CL. Effects of isometric handgrip training dose on resting blood pressure and resistance vessel function in normotensive women. Eur J Appl Physiol 2013; 113(8): 2091-2100.
13. Millar PJ, Proudfoot NA, Dillenburg RF, MacDonald MJ. Reduced heart rate variability and baroreflex sensitivity in normotensive children with repaired coarctation of the aorta. Int J Cardiol 2013; 168(1): 587-588.
14. Badrov MB, Horton S, Millar PJ, McGowan CL. Cardiovascular stress reactivity tasks successfully predict the hypotensive response of isometric handgrip training in hypertensives. Psychophysiology 2013; 50(4): 407-414.
15. McGowan CL, Murai H, Millar PJ, Notarius CF, Morris BL, Floras JS. Simvastatin reduces sympathetic outflow and augments endothelium-independent dilation in non-hyperlipidemic primary hypertension. Heart 2013; 99: 240-246.
16. Montemurro LT, Floras JS, Millar PJ, Kasai T, Gabriel JM, Spaak J, Coelho FMS, Bradley TD. Inverse relationship of subjective daytime sleepiness to sympathetic activity in heart failure patients with obstructive sleep apnea. Chest 2012; 142(5): 1222-1228.
17. Currie KD, Martin AA, Millar PJ, Timmons BW, Dillenburg R, MacDonald MJ. Vascular and autonomic function in preschool-aged children with congenital heart disease. Congenit Heart Dis 2012; 7(3): 289-297.
18. Millar PJ, Levy AS, McGowan CL, McCartney N, MacDonald MJ. Isometric handgrip training lowers blood pressure and increases heart rate complexity in medicated hypertensive patients. Scand J Med Sci Sports 2013; 23: 620-626. (Epub Jan 20, 2012).
19. Millar PJ, Murai H, Floras JS. Neurogenic retrograde arterial flow during obstructive sleep apnea: A novel mechanism for endothelial dysfunction? Hypertension 2011; 58(3): e17-18.
20. Stuckey MI, Tordi N, Mourot L, Gurr L, Rakobowchuk M, Millar PJ, Toth R, MacDonald MJ, Kamath MV. Autonomic recovery following sprint interval exercise. Scand J Med Sci Sports 2012; 22(6): 756-763.
21. Millar PJ, MacDonald MJ, McCartney N. Effects of isometric handgrip protocol on blood pressure and neurocardiac modulation. Int J Sports Med 2011; 32(3): 174-180.
22. Millar PJ, Cotie LM, St. Amand T, McCartney N, Ditor DS. Effects of autonomic blockade on nonlinear heart rate dynamics. Clin Auton Res 2010; 20(4): 241-247.