Expression and functional evidence of the prostaglandin F2alpha receptor mediating contraction in human umbilical vein.

Our purposes were to perform the pharmacological characterization of PGF(2alpha) receptor (prostanoid FP-receptor) involved in human umbilical vein contraction and confirm its expression in this tissue. Umbilical cords from healthy patients after full-term deliveries were employed. The vein was dissected out of cords and used for either isolated organ bath or reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assays. The natural prostanoid FP-receptor agonist, PGF(2alpha), and its selective analogues, latanoprost and bimatoprost free acids are full agonists (produce more than 80% of the maximal contractile response to 5-HT) in human umbilical vein. The agonist potency (pEC(50)) order was PGF(2alpha) (6.01+/-0.05)>latanoprost free acid (5.65+/-0.07)=bimatoprost free acid (5.59+/-0.08). The contractile effects of PGF(2alpha) and latanoprost free acid were blocked competitively by the prostanoid FP-receptor antagonist, AL-8810. The antagonist potencies (pK(B)) of AL-8810 vs. PGF(2alpha) (5.93+/-0.05) and vs. latanoprost free acid (6.40+/-0.08) in human umbilical vein are in good agreement with its ability to antagonize prostanoid FP receptors of rat, mouse and human cells. In all samples, clear signal was detected for cDNA amplification of prostanoid FP receptor and the specific prostanoid FP-receptor antibody recognized a protein of approximately 64 kDa. In conclusion, taking into account the obtained functional and biochemical data, we propose for the first time that human umbilical vein express prostanoid FP-receptors and these receptors could be involved in the vasoconstriction action of PGF(2alpha) in this tissue.

Bimatoprost (Lumigan((R))) is an agonist at the cloned human ocular FP prostaglandin receptor: real-time FLIPR-based intracellular Ca(2+) mobilization studies.

Bimatoprost is the ethyl amide derivative of 17-phenyl-trinor prostaglandin F(2alpha). Here, we show that bimatoprost (K(i)=9250+/-846nM) and bimatoprost free acid (17-phenyl-trinor prostaglandin F(2alpha); K(i)=59+/-6nM) bind to the FP receptor and displace [(3)H]-travoprost acid, a selective FP agonist. Bimatoprost (EC(50)=3070+/-1330nM), Lumigan((R)) (bimatoprost 0.03% ophthalmic solution; EC(50)=1150+/-93nM) and bimatoprost acid (EC(50)=15+/-3nM) mobilized intracellular Ca(2+) ([Ca(2+)](i)) in <5s in HEK-293 cells expressing the cloned human ciliary body FP receptor on a fluorometric imaging plate reader (FLIPR). Furthermore, agonist effects of bimatoprost and bimatoprost acid were blocked by AL-8810 (11beta-fluoro-15-epi-15-indanyl prostaglandin F(2alpha); K(i)=0.7-2.1 MicroM), an FP receptor-selective antagonist. Therefore, the prodrug bimatoprost and its hydrolytic product, bimatoprost free acid, bind to and activate the human ocular FP prostaglandin receptor to mobilize [Ca(2+)](i), thus behaving as FP receptor agonists.