Characterization of leukotriene B4 binding sites on guinea pig lung macrophages.
Specific binding sites for [3H]leukotriene B4 (LTB4) were identified on guinea pig lung macrophages, using high specific activity [3H] LTB4 in the presence or absence of unlabeled LTB4. At 0 degrees C, [3H] LTB4 binding reached equilibrium within 30 min, and addition of a large excess of unlabeled LTB4 resulted in a rapid decrease of specific binding. Binding was saturable, reversible and dependent upon the number of lung macrophages. The KD and Bmax were found to be 3.85 +/- 0.6 nM and 35 +/- 3 fmol/10(6) cells, respectively, as determined from Scatchard analysis. In competition studies for the displacement of [3H]LTB4 from binding sites, LTB4 and its analogs had the following order of potency: LTB4 (Ki = 2.9 +/- 0.8 nM) greater than 5-epi LTB4 (Ki = 58.7 +/- 0.3 nM) greater than 5-deoxy-LTB4 (Ki = 91.7 +/- 0.3 nM) greater than 12-epi LTB4 (Ki = 4.7 +/- 1.2 microM) greater than 5,12-deoxy LTB4 (Ki = 7.6 +/- 0.01 microM) greater than or equal to 12-deoxy LTB4 (Ki = 8.9 +/- 0.01 microM). LTC4 and LTD4 did not displace the [3H] LTB4 binding at concentrations up to 10 microM. [3H]LTB4 was not metabolized during the binding process as determined by reverse-phase high performance liquid chromatography. It was suggested that this binding site might be an LTB4 receptor.
Cristol
J P
JP
Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Quebec, Canada.
Provençal
B
B
Borgeat
P
P
Sirois
P
P
D000818:Animals; D001665:Binding Sites; D019204:GTP-Binding Proteins / Q000502:physiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007975:Leukotriene B4 / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014316:Tritium
D014316:Tritium; D007975:Leukotriene B4; D019204:GTP-Binding Proteins