{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,16]],"date-time":"2025-10-16T20:32:34Z","timestamp":1760646754665},"reference-count":0,"publisher":"American Physiological Society","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Cell Physiology"],"published-print":{"date-parts":[[1986,6,1]]},"abstract":"<jats:p> Numerous studies indicate that synthesis and secretion of surfactant by type II pneumocytes are modulated by the interaction of beta-adrenergic agonists with specific cell surface receptors. Two 125I-labeled beta-adrenergic ligands, l-iodopindolol (IPIN) and l-iodocyanopindolol (ICYP), were thus employed to investigate the properties of type II cell beta-receptors. Saturable, high-affinity, stereospecific binding to crude membrane fractions from whole rat lungs was exhibited by both ligands (IPIN, KD 283 pM, Bmax 508 fmol\/mg protein; ICYP, KD 18 pM, Bmax 404). Type II cell membranes obtained by N2 cavitation also revealed stereospecific, saturable, high-affinity binding. In intact cells (37 degrees C) however, rapid, highly concentrative (cell\/media greater than 1000), nonspecific ligand uptake compromised estimates of specific binding (specific\/total binding less than 0.1). Total ligand uptake was inhibited at 4 degrees C, by decreasing pH within the physiological range (7-8) and by the lysosomotropic compound chloroquine (50-200 microM), without a detectable change in specific binding. Other basic drugs were also inhibitory at similar concentrations; acidic drugs had no effect. Even at 4 degrees C, specific binding remained low, as IPIN and ICYP were displaced less than 30% by l-alprenolol (1 microM). Physicochemical properties of IPIN and ICYP considered with the above studies suggest that passive ligand entry into intact pneumocytes and subsequent trapping of the protonated species in a cellular compartment of low pH may account for high nonspecific ligand uptake. <\/jats:p>","DOI":"10.1152\/ajpcell.1986.250.6.c871","type":"journal-article","created":{"date-parts":[[2017,12,24]],"date-time":"2017-12-24T09:06:09Z","timestamp":1514106369000},"page":"C871-C879","source":"Crossref","is-referenced-by-count":23,"title":["Receptor-independent sequestration of beta-adrenergic ligands by alveolar type II cells"],"prefix":"10.1152","volume":"250","author":[{"given":"J. P.","family":"Fabisiak","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S. R.","family":"Rannels","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"E. S.","family":"Vesell","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"D. E.","family":"Rannels","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"24","container-title":["American Journal of Physiology-Cell Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.physiology.org\/doi\/pdf\/10.1152\/ajpcell.1986.250.6.C871","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,6,17]],"date-time":"2024-06-17T19:53:05Z","timestamp":1718653985000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.physiology.org\/doi\/10.1152\/ajpcell.1986.250.6.C871"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1986,6,1]]},"references-count":0,"journal-issue":{"issue":"6","published-print":{"date-parts":[[1986,6,1]]}},"alternative-id":["10.1152\/ajpcell.1986.250.6.C871"],"URL":"https:\/\/doi.org\/10.1152\/ajpcell.1986.250.6.c871","relation":{},"ISSN":["0363-6143","1522-1563"],"issn-type":[{"value":"0363-6143","type":"print"},{"value":"1522-1563","type":"electronic"}],"subject":[],"published":{"date-parts":[[1986,6,1]]}}}