Developing a fluorescence-based tool to measure noradrenaline transporter function in cardiovascular tissue

Cao, Lily Lili ORCID: 0000-0002-9513-4831 (2021). Developing a fluorescence-based tool to measure noradrenaline transporter function in cardiovascular tissue. University of Birmingham. Ph.D.

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Abstract

Sympathetic noradrenergic transmission in both the heart and vasculature is modulated at central, ganglionic, and end-organ sites. It is ultimately within the neuroeffector junction where the dynamic interplay between noradrenaline (NAd) release and its subsequent reuptake by the noradrenaline transporter (NAT) that predominately determines the junctional availability of the neurotransmitter. However, despite the fact that NAT dysfunction is implicated in many cardiovascular diseases, the mechanisms that govern transporter modulation remain poorly defined due to the limited methodologies available. This study demonstrates the development and optimisation of a novel, fluorescence-based technique, NTUA (Neurotransmitter Transporter Uptake Assay), that permits dynamic measurements of NAT function at high spatiotemporal resolutions in whole organ preparations ex vivo. This technique was then used to explore putative NAT regulators. It was discovered that several known release-inhibiting modulators, such as the muscarinic acetylcholine receptor, ⍺2-adrenoceptor (⍺2AR), and cannabinoid type I receptor (CB1R), also suppress NAT function. Importantly, the neuromodulatory roles of ⍺2AR and CB1R were also uncovered during bouts of sympathetic neuronal activity, which provides further insight into the complexity of net noradrenergic transmission. Moreover, the future potential for NTUA as an intravital stain to monitor disease progression in vivo was demonstrated by its use to simultaneously detect for changes in NAT function and sympathetic nerve density in a pre-clinical animal model of obstructive sleep apnoea, a disease with complex cardiovascular implications. These data, amongst others, show that NTUA will help future research into junctional NAd availability and hence the study of sympathetic transmission in the cardiovascular system.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):