Characterization of prostanoid receptors on rat neutrophils.
1. The effects of various prostanoid agonists have been compared on the increase in intracellular free calcium ([Ca2+]i) and the aggregation reaction of rat peritoneal neutrophils induced by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). 2. Prostaglandin E2 (PGE2) and the specific IP-receptor agonist, cicaprost, both inhibited the FMLP-induced increase in [Ca2+]i (IC50 33 nM and 18 nM respectively) and the FMLP-induced aggregation reaction (IC50 5.6 nM and 7.9 nM respectively). PGD2, PGF2 alpha, and the TP-receptor agonist, U 46619, were inactive at the highest concentration tested (1 microM). 3. The EP1-receptor agonist, 17-phenyl-omega-trinor PGE2, and the EP3-receptor agonists, GR 63799X and sulprostone, had no inhibitory effect on FMLP-stimulated rat neutrophils. 4. PGE1 (EP/IP-receptor agonist) and iloprost (IP-receptor agonist) inhibited the FMLP-induced increase in [Ca2+]i with IC50 values of 34 nM and 38 nM respectively. The EP2-receptor agonists, butaprost and misoprostol (1 microM), inhibited both FMLP-stimulated [Ca2+]i and aggregation. However another EP2-receptor agonist, AH 13205, was inactive in both assays. 5. Prostanoid receptors present on rat neutrophils were further characterized by measuring [3H]-adenosine 3':5'-cyclic monophosphate ([3H]-cyclic AMP) accumulation. Only those agonists capable of stimulating [3H]-cyclic AMP accumulation were able to inhibit both FMLP-stimulated [Ca2+]i and aggregation. 6. These results indicate that rat neutrophils possess inhibitory IP and EP-receptors; the relative potencies of PGE2, misoprostol and butaprost are those expected for the EP2-receptor subtype. No evidence for DP, FP, TP or EP1 and EP3-receptors was obtained.
Department of Pharmacology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, New Territories.
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D000818:Animals; D002118:Calcium / Q000378:metabolism; D002449:Cell Aggregation / Q000187:drug effects; D000242:Cyclic AMP / Q000096:biosynthesis; D066298:In Vitro Techniques; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D011465:Prostaglandins, Synthetic / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011982:Receptors, Prostaglandin / Q000819:agonists / Q000037:antagonists & inhibitors / Q000187:drug effects*
D011448:Prostaglandin Antagonists; D011465:Prostaglandins, Synthetic; D011982:Receptors, Prostaglandin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000242:Cyclic AMP; D002118:Calcium