Real-time measurement of adenosine and ATP release in the central nervous system

Abstract

This brief review recounts how, stimulated by the work of Geoff Burnstock, I developed biosensors that allowed direct real-time measurement of ATP and adenosine during neural function. The initial impetus to create an adenosine biosensor came from trying to understand how ATP and adenosine-modulated motor pattern generation in the frog embryo spinal cord. Early biosensor measurements demonstrated slow accumulation of adenosine during motor activity. Subsequent application of these biosensors characterized real-time release of adenosine in in vitro models of brain ischaemia, and this line of work has recently led to clinical measurements of whole blood purine levels in patients undergoing carotid artery surgery or stroke. In parallel, the wish to understand the role of ATP signalling in the chemosensory regulation of breathing stimulated the development of ATP biosensors. This revealed that release of ATP from the chemosensory areas of the medulla oblongata preceded adaptive changes in breathing, triggered adaptive changes in breathing via activation of P2 receptors, and ultimately led to the discovery of connexin26 as a channel that mediates CO2-gated release of ATP from cells.

Gut-innervating TRPV1+ Neurons Drive Chronic Visceral Pain via Microglial P2Y12 Receptor

“…Such approach could be done using available sensitive and selective biosensors expressed in microglial cells of the spinal cord. 69 , 70 , 71 Microglia express several subtypes of ionotropic (P2XRs) and metabotropic purinergic receptors (P2YRs), which detect synaptic release of ATP. 34 The nature of purinergic responses is dose-dependent; low concentrations of ATP act via P2YRs, but high concentrations (millimolar range) activate P2XRs.…”

The P2Y/P2X divide: How it began

“…Furthermore, highly selective agonists and antagonists have been developed that can be used to determine the physiological and pathophysiological roles of P2X and P2Y receptors, some of which are now in clinical use. We also have a greater understanding of associated processes, such as the cellular release of ATP, which can now be followed in real time [64] and the metabolism of extracellular purines and pyrimidine nucleotides by a family of ecto-enzymes [65]. Behind it all lies Geoff Burnstock's intelligence, enthusiasm and drive.…”

Ectonucleotidases as bridge between the ATP and adenosine world: reflections on Geoffrey Burnstock

“…In the case of ATP, Di Virgilio and colleagues [ 20 ] have elegantly engineered a chimeric plasma membrane luciferase (pmeLUC), that is targeted to the outer plasma membrane and permits sensitive interstitial ATP measurements [ 20 ]. Comparable sensors for adenosine are presently not available and at best rely on electrochemical microsensors [ 21 , 22 ] and microdialysis [ 23 ]. In the future, it would be highly desirable to be able to non-invasively quantify extracellular ATP, ADP, and adenosine in a complex tissue context, since it is finally the concentration of these purine compounds which elicits signaling at the respective P1 and P2 receptors.…”