Article date: October 1994
By: J.P. Galizzi, M.C. Bodinier, B. Chapelain, S.M. Ly, L. Coussy, S. Giraud, G. Neliat, T. Jean, in Volume 113, Issue 2, pages 389-394
Binding of the specific bradykinin B1 receptor agonist, [3H]‐des‐Arg10‐kallidin (‐KD) was investigated in smooth muscle cells (SMC) isolated from rabbit mesenteric arteries (RMA).
[3H]‐des‐Arg10‐KD specifically bound to interleukin‐1 (IL‐1)‐treated RMA‐SMC in a saturable fashion with an equilibrium dissociation constant (KD) of 0.3–0.5 nm. The number of binding sites per cell was 20,000–35,000. Kinins inhibited [3H]‐des‐Arg10‐KD binding to RMA‐SMC with an order of potency very similar to that observed in typical B1 specific bioassays: des‐Arg9‐bradykinin (BK) ≅ KD > > BK. Furthermore, the B1 receptor antagonist [Leu8]des‐Arg9‐BK inhibited [3H]‐des‐Arg10‐KD binding with an IC50 of 43 nm as expected for its effect at B1 receptors. The B2 receptor antagonists, NPC 567 and Hoe 140 only affected [3H]‐des‐Arg10‐KD binding at very high concentrations (IC50 = 0.8 μm and IC50 > 10 μm, respectively).
Des‐Arg9‐BK (BL agonist) and [Hyp3]Tyr(Me)8‐BK (B2 agonist) did not induce prostacyclin (PGI2) production by RMA‐SMC. Lipopolysaccharide (LPS) treatment of the cells did not affect the B1 agonist response whereas IL‐1β treatment produced a 7 fold increase in des‐Arg9‐BK‐stimulated PGI2 production. IL‐1β also stimulated the response to B2 agonists.
Des‐Arg9‐BK‐induced PGI2 secretion in IL‐1‐primed RMA‐SMC was mediated by B1 receptors since it was inhibited by [Leu8]des‐Arg9‐BK (IC50 = 56–73 nm) but not by Hoe 140. High concentrations of NPC 567 (IC50 = 2.4 μm) were required to inhibit PGI2 production induced by B1 agonists.
IL‐1‐treated RMA‐SMC displayed a 5 fold increase in the number of B1 receptors without modification of the affinity constant, thus establishing a possible relationship between the receptor density and the IL‐1‐primed B1 response.
LPS treatment of the cells induced a 4 fold increase in B1 receptor number without modifying PGI2 secretion. This observation suggests that IL‐1 but not LPS, in addition to increase in the number of receptors, signals the cell to permit the coupling of B1 receptors to the PLA2/cyclo‐oxygenase pathway.
Binding of the specific bradykinin B1 receptor agonist, [3H]‐des‐Arg10‐kallidin (‐KD) was investigated in smooth muscle cells (SMC) isolated from rabbit mesenteric arteries (RMA).
[3H]‐des‐Arg10‐KD specifically bound to interleukin‐1 (IL‐1)‐treated RMA‐SMC in a saturable fashion with an equilibrium dissociation constant (KD) of 0.3–0.5 nm. The number of binding sites per cell was 20,000–35,000. Kinins inhibited [3H]‐des‐Arg10‐KD binding to RMA‐SMC with an order of potency very similar to that observed in typical B1 specific bioassays: des‐Arg9‐bradykinin (BK) ≅ KD > > BK. Furthermore, the B1 receptor antagonist [Leu8]des‐Arg9‐BK inhibited [3H]‐des‐Arg10‐KD binding with an IC50 of 43 nm as expected for its effect at B1 receptors. The B2 receptor antagonists, NPC 567 and Hoe 140 only affected [3H]‐des‐Arg10‐KD binding at very high concentrations (IC50 = 0.8 μm and IC50 > 10 μm, respectively).
Des‐Arg9‐BK (BL agonist) and [Hyp3]Tyr(Me)8‐BK (B2 agonist) did not induce prostacyclin (PGI2) production by RMA‐SMC. Lipopolysaccharide (LPS) treatment of the cells did not affect the B1 agonist response whereas IL‐1β treatment produced a 7 fold increase in des‐Arg9‐BK‐stimulated PGI2 production. IL‐1β also stimulated the response to B2 agonists.
Des‐Arg9‐BK‐induced PGI2 secretion in IL‐1‐primed RMA‐SMC was mediated by B1 receptors since it was inhibited by [Leu8]des‐Arg9‐BK (IC50 = 56–73 nm) but not by Hoe 140. High concentrations of NPC 567 (IC50 = 2.4 μm) were required to inhibit PGI2 production induced by B1 agonists.
IL‐1‐treated RMA‐SMC displayed a 5 fold increase in the number of B1 receptors without modification of the affinity constant, thus establishing a possible relationship between the receptor density and the IL‐1‐primed B1 response.
LPS treatment of the cells induced a 4 fold increase in B1 receptor number without modifying PGI2 secretion. This observation suggests that IL‐1 but not LPS, in addition to increase in the number of receptors, signals the cell to permit the coupling of B1 receptors to the PLA2/cyclo‐oxygenase pathway.
DOI: 10.1111/j.1476-5381.1994.tb17001.x
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