ATP-induced intracellular Ca2+ signals in isolated human insulin-secreting cells

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Abstract
Using isolated β-cells from human islets of Langerhans we have demonstrated that purinergic receptor agonists are functionally coupled to rises in the intracellular calcium ion concentration ([Ca2+]i). The effects of ATP, ADP and AMP have been examined over a range of concentrations, 0.5 to 500μM. The actions of ATP were more potent than those of either ADP or AMP suggesting that a P2-type of purinergic receptor operates in these cells. Responses to ATP were concentration-related, but exhibited marked desensitisation at high concentrations (>100μM). Purinergic receptor agonists elevate [Ca2+]i by mechanisms that involve both Ca2+ influx and Ca2+ mobilisation from intracellular stores. The physiological significance of our data has been discussed, and related to previous studies carried out upon rodent and clonal insulin-secreting cells.