Beta-adrenoceptor-mediated control of apical membrane conductive properties in fetal distal lung epithelia.
Distal lung epithelial cells isolated from fetal rats were cultured (48 h) on permeable supports so that transepithelial ion transport could be quantified electrometrically. Unstimulated cells generated a short-circuit current (I(sc)) that was inhibited (~80%) by apical amiloride. The current is thus due, predominantly, to the absorption of Na(+) from the apical solution. Isoprenaline increased the amiloride-sensitive I(sc) about twofold. Experiments in which apical membrane Na(+) currents were monitored in basolaterally permeabilized cells showed that this was accompanied by a rise in apical Na(+) conductance (G(Na(+))). Isoprenaline also increased apical Cl- conductance (G(Cl-)) by activating an anion channel species sensitive to glibenclamide but unaffected by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). The isoprenaline-evoked changes in G(Na(+)) and G(Cl(minus sign)) could account for the changes in I(sc) observed in intact cells. Glibenclamide had no effect upon the isoprenaline-evoked stimulation of I(sc) or G(Na(+)) demonstrating that the rise in G(Cl-) is not essential to the stimulation of Na(+) transport.
Collett
A
A
Lung Membrane Transport Group, Tayside Institute of Child Health, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
Ramminger
S J
SJ
Olver
R E
RE
Wilson
S M
SM
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D016764:Cell Polarity / Q000502:physiology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D015194:Diffusion Chambers, Culture; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D015633:Extravascular Lung Water / Q000378:metabolism; D005260:Female; D005333:Fetus / Q000166:cytology; D005905:Glyburide / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011247:Pregnancy; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D018118:Chloride Channels; D002712:Chlorides; D016895:Culture Media, Serum-Free; D007004:Hypoglycemic Agents; D011943:Receptors, Adrenergic, beta; D015222:Sodium Channels; D001464:Barium; D012964:Sodium; D007545:Isoproterenol; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D005905:Glyburide