title: P2-purinoceptors regulate surfactant secretion from rat isolated alveolar type II cells.
abstract: Rat isolated alveolar Type II cells were utilized to examine the effect of purine and pyrimidine analogues on secretion of pulmonary surfactant. ATP potently stimulated [3H]-phosphatidylcholine ([3H]-PC) secretion in a time- and dose-dependent manner. The effect of ATP was noted by one hour of exposure and persisted for three hours. The EC50 (concentration producing 1/2 the maximal response) for ATP-induced [3H]-PC secretion was 100 nM. ADP was also a potent secretagogue for surfactant secretion, but AMP and adenosine had no significant effect on surfactant secretion at concentrations less than or equal to 250 microM. The EC50 for ADP-induced [3H]-PC secretion was 250 nM. Other purine and pyrimidine nucleotides (ITP, GTP, CTP, TTP) were examined for their effect on [3H]-PC secretion. All purine and pyrimidine triphosphates examined significantly augmented [3H]-PC secretion, but were much less potent than ATP. The EC50s were ITP = 10 microM; GTP = 100 microM; CTP = 250 microM; TTP = 100 microM. Neither 8-phenyltheophylline (10 microM, a P1-purinoceptor antagonist), propranolol (100 microM, a beta-adrenoceptor antagonist), nor indomethacin (10 microM, a prostaglandin synthetase inhibitor) inhibited ATP-induced [3H]-PC secretion from isolated Type II cells. These data provide evidence for regulation of surfactant secretion from alveolar Type II cells by a P2-purinoceptor.
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D010713:Phosphatidylcholines / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000378:metabolism*; D011685:Purine Nucleotides / Q000494:pharmacology; D011742:Pyrimidine Nucleotides / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*
chemical_list: D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D011685:Purine Nucleotides; D011742:Pyrimidine Nucleotides; D011983:Receptors, Purinergic