Electrophysiology of autonomic neuromuscular transmission involving ATP.
Electrophysiological investigations of autonomic neuromuscular transmission have provided great insights into the role of ATP as a neurotransmitter. Burnstock and Holman made the first recordings of excitatory junction potentials (e.j.p.s) produced by sympathetic nerves innervating the smooth muscle of the guinea-pig vas deferens. This led to the identification of ATP as the mediator of e.j.p.s in this tissue, where ATP acts as a cotransmitter with noradrenaline. The e.j.p.s are mediated solely by ATP acting on P2X(1) receptors leading to action potentials and a rapid phasic contraction, whilst noradrenaline mediates a slower, tonic contraction which is not dependent on membrane depolarisation. Subsequent electrophysiological studies of the autonomic innervation of smooth muscles of the urogenital, gastrointestinal and cardiovascular systems have revealed a similar pattern of response, where ATP mediates a fast electrical and mechanical response, whilst another transmitter such as noradrenaline, acetylcholine, nitric oxide or a peptide mediates a slower response. The modulation of junction potentials by a variety of pre-junctional receptors and the mechanism of inactivation of ATP as a neurotransmitter will also be described.
Sneddon
P
P
Department of Physiology & Pharmacology, University of Strathclyde, Strathclyde Institute of Biomedical Sciences, 27 Taylor Street, G4 0NR, Glasgow, UK. p.sneddon@strath.ac.uk
D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D004594:Electrophysiology; D006801:Humans; D009045:Motor Endplate / Q000502:physiology; D009469:Neuromuscular Junction / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D018377:Neurotransmitter Agents; D000255:Adenosine Triphosphate