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Substance P, neurokinin A and neurokinin B in the ocular response to injury in the rabbit
Author(s) -
BedingBarnekow Britt,
Brodin Ernst,
Håkanson Rolf
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.tb16572.x
Subject(s) - neurokinin a , substance p , neurokinin b , medicine , endocrinology , miosis , stimulation , in vivo , chemistry , neuropeptide , biology , pharmacology , receptor , microbiology and biotechnology
1 Substance P (SP) and neurokinin A‐ (NKA)/neurokinin B (NKB)‐like immunoreactivity (LI) were measured by radioimmunoassay in extracts of the rabbit uvea. The iris‐ciliary body complex contained 3–4 times more NKA/NKB‐LI than SP‐LI. Tachykinins are thought to mediate many of the responses to ocular injury in the rabbit. Their possible role in the miosis and breakdown of the blood‐aqueous barrier (BAB) was studied in vitro and in vivo . 2 In vitro , NKA had a more short‐lasting contractile effect on the sphincter pupillae muscle than either SP or NKB, but SP was more potent than the other two. The tachykinin antagonist, spantide, dose‐dependently suppressed the response to electrical stimulation (by 90% at 10 −4 M ) and to the three tachykinins. An antiserum against SP (no cross‐reaction with NKA or NKB) greatly suppressed the response to SP (by 90%) as well as to electrical field stimulation (by 40%). The responses to NKA and NKB were unaffected. 3 In vivo studies revealed that SP was more potent than NKA and NKB as a miotic. SP evoked a moderate breakdown of the BAB at high doses while NKA and NKB were virtually inactive. 4 We conclude that besides SP other tachykinins might play a role in the mediation of miosis in the rabbit eye but, of the three peptides investigated, only SP can be of importance for the break‐down of the BAB.