title: Substance P: immunohistochemical localization and effect upon cat pial arteries in vitro and in situ.
abstract: 1. Nerve fibres containing substance P immunoreactivity were present in the adventitia and the adventitia-media border of all cat cerebral arteries which were examined. Substance P immunoreactivity was most abundant in cerebral arteries from the rostral portion of the circle of Willis. 2. Substance P effected a dose-dependent relaxation of feline middle cerebral arteries which had been contracted with prostaglandin F2 alpha. The maximum relaxation (16 +/- 0.3 mN) was achieved with substance P at a concentration of 10-6 M. 3. In cats anaesthetized with alpha-chloralose, the perivascular microinjection of substance P effected dose-dependent increases in arteriolar calibre. The maximum increase in calibre (19 +/- 3%) was observed following the injection of 10(-6) M-substance P.
mesh_terms: D000818:Animals; D002415:Cats; D002536:Cerebral Arteries / Q000032:analysis* / Q000187:drug effects; D004027:Diencephalon / Q000032:analysis / Q000098:blood supply; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D013373:Substance P / Q000032:analysis* / Q000494:pharmacology
chemical_list: D013373:Substance P