title: Terbutaline-induced triphasic changes in volume of rat alveolar type II cells: the role of cAMP.
abstract: Changes in the volume of rat alveolar type II cells (AT-II cells) induced by terbutaline, a beta(2)-agonist, were measured using video-enhanced contrast microscopy. The changes consisted of three phases: initial cell shrinkage, cell swelling, and gradual cell shrinkage. The initial cell shrinkage was Ca(2+)-dependent and was inhibited by quinine (a K+ channel blocker). The subsequent cell swelling was cAMP-dependent and was inhibited by amiloride (a Na+ channel blocker). The final cell shrinkage was cAMP-dependent and was inhibited by 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB, a Cl- channel blocker). Thus, terbutaline-induced cell volume changes were regulated by both Ca2+ and cAMP. Accumulation of cAMP alone, however, induced the Ca2+ -dependent cell shrinkage of AT-II cells and H-89 (a PKA inhibitor) inhibited terbutaline-induced cell volume changes. This suggests that cAMP accumulation stimulates the Ca2+ signal during terbutaline stimulation. In conclusion, terbutaline stimulates not only Na+ influx, but also K+ and Cl- release mediated via cAMP accumulation in rat AT-II cells, which induces the triphasic cell volume changes.
authors.affiliation: Department of Internal Medicine, Osaka Medical College, Takatsuki, 569-8686 Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Hosoi
authors.forename: Kyong-Yob
authors.initials: KY
authors.lastname: Min
authors.forename: Chisa
authors.initials: C
authors.lastname: Shiima
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hanafusa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mori
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakahari
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D018715:Microscopy, Video / Q000379:methods; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D013726:Terbutaline / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000318:Adrenergic beta-Agonists; D015221:Potassium Channels; D015222:Sodium Channels; D005576:Colforsin; D015759:Ionomycin; D019284:Thapsigargin; D000584:Amiloride; D011803:Quinine; D000242:Cyclic AMP; D013726:Terbutaline; D002118:Calcium