P2Y‐purinoceptor regulation of surfactant secretion from rat isolated alveolar type II cells is associated with mobilization of intracellular calcium
WR Rice, FM Singleton - British journal of pharmacology, 1987 - Wiley Online Library
WR Rice, FM Singleton
British journal of pharmacology, 1987•Wiley Online Library1 The effect of methylene, thio, and imido substituted analogues of adenosine 5′‐
triphosphate (ATP) on surfactant phospholipid secretion and calcium mobilization in rat
isolated alveolar Type II cells was studied. 2 ATP was the most potent secretagogue of
adenine nucleotides studied. The rank order of agonist potency for [3H]‐phosphatidylcholine
secretion was ATP> adenosine 5′‐O‐(3‐thiotriphosphate)(γS‐ATP)> β, γ‐imido adenosine
5′‐triphosphate (AMPPNP)> β, γ‐methylene adenosine 5′‐triphosphate (β, γ‐CH2 …
triphosphate (ATP) on surfactant phospholipid secretion and calcium mobilization in rat
isolated alveolar Type II cells was studied. 2 ATP was the most potent secretagogue of
adenine nucleotides studied. The rank order of agonist potency for [3H]‐phosphatidylcholine
secretion was ATP> adenosine 5′‐O‐(3‐thiotriphosphate)(γS‐ATP)> β, γ‐imido adenosine
5′‐triphosphate (AMPPNP)> β, γ‐methylene adenosine 5′‐triphosphate (β, γ‐CH2 …
- 1The effect of methylene, thio, and imido substituted analogues of adenosine 5′‐triphosphate (ATP) on surfactant phospholipid secretion and calcium mobilization in rat isolated alveolar Type II cells was studied.
- 2ATP was the most potent secretagogue of adenine nucleotides studied. The rank order of agonist potency for [3H]‐phosphatidylcholine secretion was ATP > adenosine 5′‐O‐(3‐thiotriphosphate) (γS‐ATP) > β, γ‐imido adenosine 5′‐triphosphate (AMPPNP) > β, γ‐methylene adenosine 5′‐triphosphate (β, γ‐CH2‐ATP) > α, β‐methylene adenosine 5′‐triphosphate (α, β‐CH2‐ATP). The respective EC50s were 10−6 m, 2 × 10−6 m, 2 × 10−5 m, 5 × 10−5 m, and > 2.5 × 10−4 m.
- 3Exogenous ATP also induced a rapid mobilization of intracellular calcium monitored by changes in Fura 2 fluorescence. The rank order of agonist potency for calcium mobilization was similar to the rank order of agonist potency for surfactant secretion: ATP = γS‐ATP > AMPPNP > α, β‐CH2‐ATP.
- 4There was no effect of EGTA on ATP‐induced calcium mobilization, consistent with the hypothesis that exogenous ATP induces release of calcium from intracellular stores.
- 5These data are consistent with a P2Y‐purinoceptor regulating surfactant secretion from isolated Type II cells via mobilization of intracellular calcium, since: (a) non‐hydrolyzed analogues of ATP are potent secretagogues, (b) β, γ‐CH2‐ATP was a more potent secretagogue than α, β‐CH2‐ATP and (c) the rank orders of agonist potency for calcium mobilization and phospholipid secretion were the same.
Wiley Online Library