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Simon McMullan

Senior Lecturer, Neurophysiology

Biomedical Sciences, Faculty of Medicine and Health Sciences

Contact Details

Tel: 02 9850 2710

Email: simon.mcmullan@mq.edu.au

2 Technology Place, Macquarie University NSW 2109, Australia

Qualifications:

PhD University of Bristol, UK, BSc (Hons) University of Manchester, UK

Research Interests

Cardiovascular disease (CVD) is the main determinant of life expectancy worldwide; Australia follows the global trend. 35% of all 2005 deaths in Australia were attributable to CVD, with another 1.5 million disabled. CVD prevalence has increased by 18% in the last decade and the direct cost of CVD is estimated at $5.9 billion and rising. The most significant risk factor for all CVD is high blood pressure, but high blood pressure remains poorly treated and poorly understood.

The sympathetic nervous system is a subdivision of the central nervous system contained within the midbrain, brainstem and spinal cord. The activity of sympathetic nerves maintains blood pressure and determines the flow of blood between different compartments of the body. The principal haemodynamic effects of sympathetic nerve activity (SNA) are vascular smooth muscle contraction and increased cardiac output. Both of these effects elevate blood pressure.

My principle research goal is to determine what factors drive the activity of neurons in the brain that control the sympathetic nervous system. We believe that the activity of these neurons is driven by convergent inputs from many other regions of the brain; our immediate goal is to determine where such inputs arise from, and to establish which ones are important in determining the ongoing activity of these cells, and hence influence blood pressure.

We use a combination of recording techniques that allow us to measure in the activity of so-called sympathetic premotor neurons in the brainstem in living rats and in slices of brain maintained in a petri dish. These experiments allow us to determine which neurotransmitters drive these neurons and in what circumstances neurotransmitter is released.

In order to do this we have recently developed a novel technique that allows us to deliver genes to single neurons while recording their electrical activity. This technique will allow us to use powerful new genetic tools to investigate the networks that control blood pressure.

My other research interest is the generation of sensory information by primary afferent fibres in the periphery and the modification of these signals in disease states. We have shown that many diseases, such as inflammatory or neuropathic conditions evoked by nerve injury, can change the expression of ion channels in primary afferent fibres and that such changes underlie the increase in excitability seen in these conditions.

Select Publications

  1. McMullan S & Pilowsky PM (2012). Sympathetic premotor neurones project to and are influenced by neurones in the contralateral rostral ventrolateral medulla of the rat in vivo. Brain Research 1439, 34-43.
  2. Korim WS, Egwuenu E, Fong AY, McMullan S, Cravo SL & Pilowsky PM (2012). Noxious somatic stimulus diminishes the respiratory-sympathetic coupling by selective resetting of the respiratory rhythm in anaesthetised rat. Exp Physiol.
  3. Korim WS, McMullan S, Cravo SL & Pilowsky PM (2011). Asymmetrical changes in lumbar sympathetic nerve activity following stimulation of the sciatic nerve in rat. Brain Res 1391, 60-70.
  4. Burke PG, Neale J, Korim WS, McMullan S & Goodchild AK (2011). Patterning of somatosympathetic reflexes reveals nonuniform organization of presympathetic drive from C1 and non-C1 RVLM neurons. Am J Physiol Regul Integr Comp Physiol 301, R1112-1122.
  5. Parekh A, Campbell AJ, Djouhri L, Fang X, McMullan S, Berry C, Acosta C & Lawson SN (2010). Immunostaining for the alpha3 isoform of the Na+/K+-ATPase is selective for functionally identified muscle spindle afferents in vivo. J Physiol 588, 4131-4143

Recent Grants

  • 2010 - 2012 National Health and Medical Research Council Project Grant 604002 (Pilowsky & McMullan) $258,750. Understanding parts of the brain that control blood pressure
  • 2012-2015 National Health and Medical Research Council Project Grant 1028183 (Goodchild AK, McMullan S & Gray PA) $548,675: What neurons maintain sympathetic vasomotor tone?
  • 2012-2015 Australian Research Council Discovery Project DP120100920 (McMullan S, Goodchild AK & Allen AM) $320,000: Mapping the connectome that controls blood pressure
  • 2010 Macquarie University Research Development Scheme (Wong D & McMullan S) $27,000 Development and characterisation of fouling-resistant hydrogenated ultramicrocarbon electrodes for in vivo neurotransmitter detection
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