THE BINDING OF [³H]‐PROSTACYCLIN TO MEMBRANES OF A NEURONAL SOMATIC HYBRID

Abstract

[3H]‐prostacylin bound to a washed membrane preparation of the NCB‐20 neuronal hybrid cell line. Kinetic analysis of [3H]‐prostacyclin binding suggested a simple, non‐cooperative bimolecular interaction between the ligand and a single receptor population. The equilibrium dissociation constant was 16.6 nm, and binding at a saturating [3H]‐prostacyclin concentration enabled the receptor density of 2.57 × 105 receptor molecules per cell to be calculated. At 20°C the rate constant for the forward reaction (k+1) was 2.26 × 105 m−1 s−1, and the rate constant for the dissociation of the ligand‐receptor complex (k‐1) was 3.85 × 10−3 s−1. Thus the dissociation constant (k‐1/k+1) was 17.0 nm. Prostaglandin E1 and prostacyclin compete for a single receptor in these cells, and comparison of other prostaglandins as inhibitors of [3H]‐prostacyclin binding revealed some of the structural requirements for high‐affinity occupation of prostacyclin receptors.

Prostanoid receptors involved in the relaxation of human bronchial preparations

“…These variations may be due to the short half life of this prostaglandin. Blair & McDermot (1981), Corsini et al (1987) and Adie et al (1992) have shown that PGE 1 , a more stable endogenous prostanoid, is a potent agonist for the IP-receptor in both binding and physiological studies. The eective relaxations of the human bronchi observed with PGE 1 (present report) suggest that, this prostaglandin, may be the preferential natural activator for IP-receptor in human airways in vivo.…”

Induction of prostacyclin receptor expression in human erythroleukemia cells

“…PGI2 receptor sites have been identified in several tissues, including platelets [1,2], vascular smooth muscle [3] and the NCB-20 cell line [4]. Both the platelet and vascular effects of PGI2 appear to be mediated, via a G-protein, by the adenylate cyclase enzyme.…”

Prostaglandin endoperoxide analogues which are both thromboxane receptor antagonists and prostacyclin mimetics

“…Bound and free radioligand were separated by rapid centrifugation after incubation for 4 min at room temperature. NCB-20 cells NCB-20 cells were cultured and homogenates and membrane suspensions prepared as described previously (Blair & MacDermot, 1981 Isolated smooth muscle preparations Spiral strips of rabbit aorta, dog saphenous vein and guinea-pig trachea were set up in conventional organ baths (8 ml) for isometric tension recording as described previously (Jones et al, 1982 In human PRP, AH 6809 counteracts PGD2-induced inhibition of aggregation whereas the action of PGI2 is slightly enhanced (Keery & Lumley, 1985 Figure 4). These concentrations are at least 300 fold higher than those used in the aggregation experiments and this provides additional evidence that thromboxane receptor block does not make a significnt contribution to the inhibitory action of EP 035 and EP 157.…”