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Calcium mobilization and response recovery following P 2 ‐purinoceptor stimulation of rat isolated alveolar type II cells
Author(s) -
Dorn Curtis C.,
Rice Ward R.,
Singleton Fannie M.
Publication year - 1989
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.1476-5381.1989.tb11938.x
Subject(s) - extracellular , phospholipid , stimulation , intracellular , medicine , endocrinology , calcium , chemistry , adenosine triphosphate , secretion , calcium in biology , biophysics , biochemistry , biology , membrane
1 The effect of adenosine 5′‐triphosphate (ATP) on surfactant phospholipid secretion, calcium mobilization, and the time course for recovery of the response system was studied in isolated alveolar Type II cells of the rat. 2 ATP (10 μ m ) stimulated a biphasic intracellular Ca 2+ transient monitored by changes in Fura‐2 fluorescence, from a basal level of 126 ± 9 n m , to a rapid peak of 391 ± 1 n m , followed by a prolonged plateau 26 ± 4 n m above baseline (mean ± s.e.mean, n = 26). 3 ATP‐stimulated surfactant phospholipid secretion and peak Ca 2+ levels had similar EC 50 s** (1 × 10 −6 m ), and were unaffected by chelation of extracellular Ca 2+ . However, the prolonged plateau phase was abolished by chelation of extracellular Ca 2+ . 4 There was a 15 min refractory period before full recovery of the Ca 2+ ‐response to ATP. Recovery was dependent on extracellular Ca 2+ , was accelerated by removing extracellular agonist and was prolonged following stimulation with the poorly hydrolyzed ATP analogue, ATP‐γ‐S. 5 While the Type II cell was capable of multiple ATP‐induced Ca 2+ transients following recovery, no additional surfactant phospholipid was released with sequential stimulation. 6 These findings suggest initial exposure of Type II cells to ATP mobilizes intracellular Ca 2+ , stimulates phospholipid secretion and rapidly desensitizes the cell to further stimulation by ATP. Recovery of the ATP‐induced Ca 2+ ‐response depends on presence of extracellular Ca 2+ and removal of agonist.