My group investigates the mechanisms by which our respiratory system adapts to changes in blood pH. There are specific cells in the brain that drive breathing when stimulated. These neurons are called chemoreceptors because they are sensitive to different chemical signals, such as the level of acid or base in the blood. In an effort to maintain a normal blood pH, these cells monitor the acidity of the blood, which becomes increasingly acidic in the presence of carbon dioxide (CO2), a by-product of metabolism that must be expelled. If higher than normal levels of acid are detected in the blood, these cells become excited and increase breathing to expel the excess carbon dioxide.
Broader significance of chemoreception:
- Acid sensing neurons in the brain drive ventilation to increase breathing (Kumar NN et al 2015, Science). There is potential for drugs that activate the acid sensing neurons, to help those afflicted by respiratory diseases, such as sleep apnea.
- Rising atmospheric CO2 causing ocean acidification has a broad impact on marine ecosystems. pH sensing mechanisms are used by fish to locate food (Caprio J et al Science 2014), oysters to build shells (Service RF 2012 Science) and coral to control calcification rates (Holcomb M et al 2014). Identification and characterization of the molecules and cellular mechanisms conferring pH sensing in marine organisms may help better predict their responses to ocean acidification, which is up 30% since preindustrial times.
- When CO2 levels rise in the hive, worker bees show up at the hive entrance and fan in place until CO2 levels in the hive decline
- Mosquitoes are attracted to CO2 exhaled by mammals
Field of Research (FoR)
My lab investigates cellular and physiological mechanisms used by autonomic systems; cardiovascular, respiratory and glucoregulatory. Physiological reflexes (e.g. baroreflex, chemoreflex, glucose counterregulation) function to maintain homeostasis in the healthy state. They are integrated by neuronal circuits in the brain, and their long term and short term patency is continually regulated by genetic and environmental factors....view more
My lab investigates cellular and physiological mechanisms used by autonomic systems; cardiovascular, respiratory and glucoregulatory. Physiological reflexes (e.g. baroreflex, chemoreflex, glucose counterregulation) function to maintain homeostasis in the healthy state. They are integrated by neuronal circuits in the brain, and their long term and short term patency is continually regulated by genetic and environmental factors. Pathological regulation can form the basis for disease (respiratory disorders, hypertension, diabetes). How do homeostatic systems - which are vital for survival - adapt to changing environmental conditions? How do environmental challenges contribute to neuronal excitability, physiological processes and drug action?
We have expertise in cutting-edge tools and techniques (molecular methods, mouse genetics, imaging techniques, viral mediated gene rescue and knockdown) that are currently revolutionizing neuroscience. We use these skills to interrogate alterations in autonomic systems following physiological/environmental stress and provide avenues for therapy based on molecular understanding of disease processes.
Qualifications: BMedSc (Hons1) USYD, PhD USYD
PhD and Honours projects/topics available include:
TOPIC - Respiratory chemoreception: Inhibitory neuropeptides in respiratory chemoreceptors: what is their contribution to ventilatory behaviour? How is this role altered during chronic respiratory/environmental stress (e.g. sleep apnea, chronic obstructive pulmonary disease, obesity hypoventilation syndrome, apnea of prematurity).
Project 1: This project will investigate human infant brain chemoreceptor populations. The effects of acute versus chronic intermittent hypercapnic hypoxia on protein expression in these chemoreceptor populations will be determined. Finally, protein expression changes in Sudden Infant Death Syndrome (SIDS), compared to control infants will be investigated.
Project 2: Does chronic hypercapnia exposure cause neuroinflammation? Implications for sleep apnea and apnea of prematurity
Project 3: Does chronic hypercapnia exposure alter neuropeptide protein expression in brain respiratory chemoreceptor populations? Implications for sleep apnea
TOPIC - Glucose counterregulation: Nearly all sympathetic preganglionic neurons that are activated by hypoglycaemia, to execute adrenalin release via adrenal chromaffin cells, are enkephalinergic. In human studies, the similarities between hypoglycemia associated autonomic failure (HAAF) and exercise associated autonomic failure (EAAF) suggest that they share a common pathophysiology. How do endogenous opioid neuropeptides regulate the glucose countergulatory response to hypoglycemia? How is deterioration in the response to hypoglycemia seen in Type 1 diabetic patients also induced by exercise?
Teaching: Contributions to pharmacology teaching for both science and medical students. Particular areas of expertise are autonomic neuroscience, animal behaviour and cardiorespiratory physiology.
Society Memberships & Professional Activities: Society for Neuroscience, American Physiological Society, Australasian Neuroscience Society, Franklin Women.
- 2018-2020 NN Kumar, J Power, S McMullan, SBG Abbott. Australian Research Council Discovery Project grant. Adaptation of respiratory chemoreception: role of inhibitory neuropeptides. $400,000
- 2018-2019 NN Kumar Rebecca Cooper Foundation project grant $100,000
- 2020-2021 NN Kumar NHMRC (65%) and UNSW Medicine/MWAC RIS (35%) infrastructure project grant. Zeiss microscope, ApoTome and MicroBrightfield software- fully integrated system $377,566
BMedSc (Hons1) USYD, PhD USYD
My Research Supervision
Areas of supervision
Please contact DR NATASHA KUMAR about ILP, HONOURS, Masters and PhD projects.
2016 - Ayse Dereli (The role of galanin in long term adaptation of respiratory chemoreception)
2018 - Latifa Bulbul (The role of neuropeptide co-release and co-signalling on the respiratory chemoreflex)
2020 - Yazhou (Susanne) Liu (Investigation of chemoreceptors in post-mortem brain tissue from patients with respiratory disorders)
2020 - Emma O'Rourke
2020 - June Sun
2018 Zarwa Yaseen (1st Class Honours awarded)
2018 Alex Ruhoff (Honours - co-supervision with Dr Nicole Jones)
2018 Josh Dunn (Honours co-supervision with Dr Nicole Jones)
2017 Felicity Duong (Honours - co-supervision with A/Prof Pascal Carrive)
2017 Giuliana Connor (Honours- co-supervision with Dr Nicole Jones)
2017 Meghety Zaitounian (Honours- co-supervision with Dr Nicole Jones)
2019: Erin Wright (ILP mark ranked 2nd out of Medicine cohort)
2019: Fasya Fazlan
I contribute to pharmacology and neurosciences teaching for both science and medical students at UNSW. Particular areas of expertise are autonomic neuroscience, animal behaviour and cardiorespiratory physiology. In the last 12 months I have lectured into the following courses: PHAR3101 (co-convenor), PHAR3102, PHAR3251, PHAR3202 (co-convenor), NEUR2201, NEUR3211, SOMS4001, NEUR4401, SOMS3001, PHAR3306 (convenor), Neuroscience Honours program (convenor).