Characterization and quantification of diadenosine hexaphosphate in chromaffin cells: Granular storage and secretagogue-induced release

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

“…The separation of the nucleotides and e-nucleotides was performed using ion pair chromatography [11]. The mobile phase contained 10 mM KH2PO4, 2 mM tetrabutyl ammonium and 15% acetonitrile, pH 7.5.…”

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

“…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). Thus, the presence of P2-purinoceptors, with high affinity for diadenosine polyphosphates, suggests the possibility of important physiological roles of these compounds in the central nervous system, as reported by Stone & Perkins (1981) (Table 2).…”

“…Ap5A, and more recently Ap6A, in chromaffin cells increases the possibility of their role as neural transmitters and modulators (Rodriguez del Castillo et Pintor et al, 1992c). In this neural model, the release of these dinucleotides after carbachol stimulation allowed their quantification in the extracellular media at concentrations in the pM range (Pintor et al, 1991a).…”

Effects of PPADS and suramin on contractions and cytoplasmic Ca2+ changes evoked by AP4A, ATP and α,β‐methylene ATP in guinea‐pig urinary bladder

“…Diadenosine polyphosphates, AP4A, AP5A and AP6A, are stored at high concentrations in bovine adrenal chromaffin cells (Rodriguez del Castillo et al, 1988;Pintor et al, 1992b) and rat brain synaptic terminals (Pintor et al, 1992a). It has been reported that AP4A, AP5A and AP6A, which are present in rat brain synaptic terminals, may have a possible role as neurotransmitters.…”