Possible functional role of diadenosine polyphosphates: negative feedback for excitation in hippocampus.
Diadenosine polyphosphates (Ap4A and Ap5A) are present in secretory granules of chromaffin cells as well as in the rat brain synaptic terminals. Their contribution to the exocytosis of the total synaptosomal content is considerable, ranging from 7% to 12%. Ap4A and Ap5A are released from synaptosomes in a Ca(2+)-dependent manner. There are indications on the high affinity of diadenosine polyphosphates to P2 receptors, but their action on P1 receptors remains unclear. Here we report that both substances induce a blocking action on excitatory synaptic transmission in the rat hippocampus. This action is elicited via the A1 (subclass of P1) receptors and differs in some respects from the action of adenosine.
Klishin
A
A
Bogomoletz Institute of Physiology, Kiev, Ukraine.
Lozovaya
N
N
Pintor
J
J
Miras-Portugal
M T
MT
Krishtal
O
O
D000818:Animals; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D005246:Feedback / Q000187:drug effects*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D018047:Receptors, Purinergic P1 / Q000187:drug effects; D013569:Synapses / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
D015226:Dinucleoside Phosphates; D018047:Receptors, Purinergic P1; C053907:8-cyclopentyl-1,3-dimethylxanthine; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C020733:diadenosine tetraphosphate; D013806:Theophylline