Presence of diadenosine polyphosphates— Ap4A and Ap5A— In rat brain synaptic terminals. Ca2+ dependent release evoked by 4-aminopyridine and veratridine

Presence of ε‐adenosine tetraphosphate in chromaffin granules after transport of ε‐ATP

“…Moreover, the presence of diadenosine polyphosphates, Ap4A, ApsA and AprA, has also been reported in catecholaminergic chromaffin granules and cholinergic vesicles from Torpedo electric organ, which are among the best characterized storage vesicles and can provide evidence about the complexity and richness of nucleotidic content in other neural or endocrine models [3][4][5].…”

Ap4A and ADP‐β‐S binding to P2 purinoceptors present on rat brain synaptic terminals

“…Synaptosomes were prepared from middle cerebral cortices of male Wistar rats cervically dislocated and decapitated as described by Pintor et al (1992a). Synaptosomes in 1 or 10 mg pellets, were resuspended into 1 ml incubation medium (composition mM: NaCl 122, KCI 3.1, KH2PO4 0.4, NaHCO3 5, MgSO4 1.2, glucose 10 and TES buffer 20, pH 7.4).…”

“…The relevance of the P2-purinoceptors with respect to the high affinity for diadenosine polyphosphates is due to the presence of these compounds and their calcium-dependent release from rat brain synaptic terminals (Pintor et al, 1992a). These dinucleotides have recently been described in catecholaminergic neurones (Pintor et al, 1992c) and in pure cholinergic vesicles from Torpedo electric organ (Pintor et al, 1992b).…”

“…The presence of diadenosine polyphosphates in the synaptosomes of rat brain, and their release by depolarizing agents, emphasized the importance of these substances as possible neurotransmitters in the central nervous system and invites the search for their physiological actions mediated by membrane receptors (Pintor et al, 1992a).…”

Adenosine-5'-O-phosphorylated and adenosine-5'-O-phosphorothioylated polyols as strong inhibitors of (symmetrical) and (asymmetrical) dinucleoside tetraphosphatases

“…Most predominant are the dinucleoside tri-and tetra-phosphates, but diadenosine penta- [2], hexa- [3] as well as di- [4] and heptaphosphates [5] have been found in some mammalian cells. The biological roles of Np n N s are still fairly obscure, with data suggesting a variety of possible functions in addition to toxic properties [6].…”