Neurotransmitters in synaptic inputs to medullary neurons subserving the baroreflex [ 2003 - 2005 ]

Research Grant

Researchers: Prof Ida Llewellyn-Smith (Principal investigator) ,  A/Pr Anthony Verberne

Brief description The baroreflex rapidly adjusts arterial blood pressure to meet changing physiological needs. The reflex alters vascular resistance and changes the rate, volume and force at which blood is expelled from the heart, ensuring that organs are adequately supplied with blood-borne nutrients and oxygen. Changes in baroreflex function occur during exercise, correlate with increased mortality and morbidity from heart failure and myocardial infarction and are responsible for postural hypotension in the elderly. Three areas in the brainstem are critical for transmission of the arterial baroreflex. However, it is still not known exactly which chemicals (neurotransmitters) are used to convey baroreflex information to and between neurons in these key sites. In this project, we will use state-of-the-art anatomical techniques to examine nerve pathways that subserve the arterial baroreflex. By changing blood pressure and specifically tagging nerve cells that respond, we can focus on neurons activated by baroreflex stimuli. Concentrating on neurotransmitters known to affect blood pressure control in the medulla, we will then label one or more of these in nerve fibers surrounding the barosensitive neurons. Finally, we will determine by light and electron microscopy the relationships between the labelled nerve fibers and the barosensitive neurons. These relationships will show which neurotransmitters could influence barosensitive neurons directly, which indirectly and which not at all. This project will increase our understanding of the baroreflex by clarifying which neurochemicals convey baroreflex information amongst the key groups of brainstem neurons. These data will form the foundation for new studies on changes in nerve pathways that underlie baroreflex dysfunction in such conditions as postural hypotension. Identifying transmitters for the baroreflex may also point to, or rule out, new drug treatments for disturbances in baroreflex function.

Funding Amount $AUD 470,500.00

Funding Scheme NHMRC Project Grants

Notes Standard Project Grant