P2-purinoceptors on postganglionic sympathetic neurones.
1. Postganglionic sympathetic neurones possess both excitatory and inhibitory P2-purinoceptors. 2. The mechanisms of action of excitatory P2-purinoceptors have recently been studied on cultured sympathetic neurones of the rat. The receptors mediate fast increases in intracellular Ca2+ levels and a release of noradrenaline. They are likely to belong to the neuronal types of P2X-purinoceptors and to be located on the sympathetic nerve cell bodies or their dendrites. 3. Inhibitory P2-purinoceptors have been shown to operate at sympathetic axon terminals in isolated tissues. Adenine nucleotides decreased the stimulation-evoked release of noradrenaline by activation of these receptors. The receptors are likely to belong to the group of G-protein-coupled P2Y-purinoceptors. They mediate a negative feedback in which co-transmitter ATP inhibits subsequent sympathetic transmitter release.
von Kügelgen
I
I
Department of Pharmacology, University of Freiburg, Germany.
Stoffel
D
D
Schobert
A
A
Starke
K
K
D000200:Action Potentials / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology*; D017779:Sympathetic Fibers, Postganglionic / Q000187:drug effects / Q000378:metabolism*
D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D009638:Norepinephrine