Pharmacological characterization of tachykinin-induced intracellular calcium rise in a human NK2 receptor transfected cell line.
We have examined the effect of various natural and synthetic tachykinins on the steady state Ca(++)-rise ([Ca++]i) in transfected chinese hamster ovary cells expressing recombinant human Neurokinin 2 (NK2) receptors. The rank order of potency with natural tachykinins was NeurokininA > Neurokinin B > Eledoisin > Physaelamin > substance P. The selective NK2 agonist, [beta-Ala8]NKA(4-10) was very potent, with an EC50 value of 4.83 x 10(-9) M whereas Senktide, MePhe7NKB and Sar9, (MetO2)11 substance P, selective NK3 and NK1 agonists, respectively, did not have any effect on [Ca++]i in hrNK2CHO cells, suggesting a selective and preferential recognition and activation of NK2 receptors in these cells. (+/-) SR 48968, a selective NK2 antagonist, abolished the beta-AlaNKA-induced [Ca++]i with an IC50 value of 0.7 nM. Two other peptidic NK2 antagonists, MEN 10376 and L-658977, were less active with IC50 values of 49 nM and 5.29 microM, respectively. In contrast, (+/-) CP-96,345 and (+/-)CP-99,994 and RP 67580, all selective NK1 antagonists, did not have any effect on the beta-AlaNKA-induced [Ca++]i in hrNK2CHO cells (+/-) SR 140333, a potent and selective NK1 antagonist, had a 35% inhibition under similar conditions. These data demonstrate a high selectivity and sensitivity to NK2 receptor mediated [Ca++]i in rhNK2R-CHO cells and may be of value as a rapid, selective test of drug action at the human NK2 receptors in vitro.
Subramanian
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N
Ciba-Geigy Ltd, Dept. of Asthma and Allergy, Basel, Switzerland.
Ruesch
C
C
Bertrand
C
C
D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D006224:Cricetinae; D006801:Humans; D066298:In Vitro Techniques; D018041:Receptors, Neurokinin-2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins; D015320:Tachykinins / Q000494:pharmacology*; D014162:Transfection
D018041:Receptors, Neurokinin-2; D011994:Recombinant Proteins; D015320:Tachykinins; D002118:Calcium