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Comparison of the binding of radiolabelled neurokinin A and eledoisin in rat cortex synaptic membranes
Author(s) -
Foster Alan C.,
Tridgett Robert
Publication year - 1988
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1988.tb11566.x
Subject(s) - eledoisin , neurokinin a , neurokinin b , substance p , tachykinin receptor , chemistry , receptor , medicine , endocrinology , radioligand , biology , neuropeptide , biochemistry
1 The binding of the 125 I‐Bolton Hunter (BH) conjugates of neurokinin A and eledoisin to synaptic plasma membranes prepared from rat cerebral cortex was investigated. 2 Saturation analyses indicated that both radioligands labelled a similar number of binding sites, but [ 125 I]BH‐eledoisin had a 7 fold higher affinity than [ 125 I]BH‐neurokinin A. 3 An identical pharmacological profile was apparent for both radioligands and tachykinin peptides inhibited the binding in the order: neurokinin B > BH‐eledoisin > kassinin > L‐363,851, eledoisin > substance P, neurokinin A > physalaemin > DiMeC 7 > substance P methylester, indicating a profile consistent with the NK 3 ‐subtype of tachykinin receptors. 4 The binding of [ 125 I]BH‐neurokinin A and [ 125 I]BH‐eledoisin was equally sensitive to inhibition by the guanosine triphosphate (GTP) analogue, guanyly‐5′‐β‐γ‐imido) diphosphate. 5 These results indicate that [ 125 I]BH‐neurokinin A and [ 125 I]BH‐eledoisin appear to label a common site in rat cerebral cortex synaptic plasma membranes with the characteristics of an NK 3 ‐receptor, and thus [ 125 I]BH‐neurokinin A is not a selective radioligand for the NK 2 ‐receptor.