Possible role of diadenosine polyphosphates in glucose-stimulated insulin release: Effects of NaF upon metabolic and functional variables in rat isolated islets
P. Courtois et al., Possible role of diadenosine polyphosphates in glucose-stimulated insulin release: Effects of NaF upon metabolic and functional variables in rat isolated islets, INT J MOL M, 5(5), 2000, pp. 493-503
Diadenosine polyphosphates, such as diadenosine triphosphate (A2P3) and dia
denosine tetraphosphate (A2P4), were recently proposed to participate in th
e stimulus-secretion coupling for nutrient-stimulated insulin release. Sinc
e NaF, an inhibitor of inorganic pyrophosphatase, was reported to lower A2P
3 and A2P4 content in glucose-stimulated pancreatic islets, its effects upo
n metabolic, cationic, biosynthetic and secretory variables in rat pancreat
ic islets were investigated in the present study. Up to a concentration clo
se to 0.1 mM, NaF failed to affect most of these variables, except for a de
crease in Ca-45 net uptake. Much higher concentrations of NaF (e.g. 5.0 mM)
were required to cause inhibition of the metabolic, ionic, biosynthetic an
d secretory responses of the islets to nutrient secretagogues. Yet, even at
this high concentration, NaF failed to lower the islet content in tritiate
d A2P3 and A2P4 in islets prelabelled with [2,8-H-3]adenosine and failed to
prevent the glucose-induced increase in such a content. It is concluded, t
herefore, that NaF may not represent a suitable tool to assess the particip
ation of diadenosine polyphosphates in the process of nutrient-induced insu
lin secretion.