Diadenosine pentaphosphate is more potent than ATP at P2X receptors in isolated rat vagus nerve.
The effects of diadenosine pentaphosphate (Ap5A), diadenosine tetraphosphate (Ap4A), alpha,beta-methyleneATP (alpha,beta-meATP), and ATP were studied on the excitability of unmyelinated axons in isolated rat vagus nerve by means of a computerized threshold tracking technique. All purinergic compounds produced an increase in excitability, however, only the effects of alpha,beta-meATP and of Ap5A were strongly reduced by 2'- (or 3') -O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP), a selective blocker for P2X1, P2X3, and heteromeric P2X2/3 receptors. The rank order of potency for TNP-ATP-sensitive excitation was determined as follows (30 microM each): alpha,beta-meATP >Ap5A >> Ap4A = ATP. These data suggest that Ap5A might be an important naturally occurring agonist for P2X receptors at the axonal membrane of unmyelinated, including nociceptive, nerve fibres.
Burgstahler
R
R
Department of Physiology, University of Munich, Germany.
Grafe
P
P
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D014630:Vagus Nerve / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D015226:Dinucleoside Phosphates; C546403:P2rx2 protein, rat; C546410:P2rx3 protein, rat; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D014662:Vasoconstrictor Agents; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate