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External ATP mimics carbachol in initiating calcium mobilization from pancreatic β‐cells conditioned by previous exposure to glucose
Author(s) -
Gylfe Erik,
Hellman Bo
Publication year - 1987
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1987.tb11322.x
Subject(s) - carbachol , endocrinology , medicine , purinergic receptor , pancreatic islets , extracellular , calcium , chemistry , efflux , beta cell , intracellular , receptor , calcium in biology , biology , insulin , stimulation , islet , biochemistry
1 Exposure to ATP (2–200 μ m ) resulted in a prominent peak of 45 Ca efflux, when β‐cell‐rich pancreatic islets from ob/ob ‐mice were perifused with a Ca 2+ ‐deficient medium. ADP and the stable α/β‐methylene analogues of ATP and ADP also had stimulatory effects. 2 The nucleotide initiation of 45 Ca efflux mimicked that obtained with carbachol both in requiring previous exposure to glucose and in being more pronounced after replacing extracellular Na + by K + . 3 It was possible to induce repeated peaks of stimulated 45 Ca efflux, when the exposure to ATP was interrupted with intervals of perifusion with glucose‐containing media. 4 The observations are consistent with the existence of P 2 ‐purinoceptors in islets, suggesting that these receptors mediate a similar mobilization of calcium as noted when activating polyphosphoinositide breakdown with carbachol. In view of the high contents of ATP and ADP in the β‐cell secretory granules, activation of P 2 ‐purinoceptors should be considered as a possible mechanism for amplification of the initial insulin secretory response.