Identification and characterization of leukotriene C4 and D4 receptors on a cultured smooth muscle cell line, BC3H-1.
We studied the characteristics of the leukotriene (LT) C4 and D4 receptors on a cultured smooth muscle cell line, BC3H-1. Specific [3H]LTC4 binding to the cell membrane was greater than 80% of total binding and saturable at a density of 3.96 +/- 0.39 pmol/mg protein, with an apparent dissociation constant (Kd) of 14.3 +/- 2.0 nM (n = 9). The association and dissociation of [3H]LTC4 binding were rapid and apparent equilibrium conditions were established within 5 min. Calculated Kd value of [3H]LTC4 binding from the kinetic analysis was 9.9 nM. From the competition analysis, calculated Ki value of unlabeled LTC4 to compete for the specific binding of [3H]LTC4 was 9.2 nM and was in good agreement with the Kd value obtained from the Scatchard plots or kinetic analysis. The rank order of potency of the unlabeled competitors for competing specific [3H]LTC4 binding was LTC4 much greater than LTD4 greater than LTE4 greater than FPL-55712. The maximum number of binding sites (Bmax) of [3H]LTD4 in the membrane of BC3H-1 cell line was about 11 times lower than that of the [3H]LTC4. The calculated values of Kd and Bmax of [3H]LTD4 binding were 9.3 +/- 0.8 nM and 0.37 +/- 0.04 pmol/mg protein, respectively (n = 3). The rank order of potency or the unlabeled competitors for competing specific [3H]LTD4 binding was LTD4 = LTE4 greater than FPL-55712 much greater than LTC4. These findings demonstrate that BC3H-1 cell line possess both LTC4 and LTD4 receptors with a predominance of LTC4 receptors. Thus BC3H-1 cell line is a good model to study the regulation of LTC4 and LTD4 receptors.
D000818:Animals; D001667:Binding, Competitive; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D009130:Muscle, Smooth / Q000378:metabolism*; D018077:Receptors, Leukotriene; D011982:Receptors, Prostaglandin / Q000378:metabolism*; D013189:SRS-A / Q000378:metabolism
D018077:Receptors, Leukotriene; D011982:Receptors, Prostaglandin; D013189:SRS-A