Effect of substance P on right colonic pressure: a dose response study in pigs.
The purpose of the present investigation was to elucidate the influence and mechanism of the action of substance P (SP) upon intraluminal pressure in proximal porcine colon. In 9 pigs, SP was infused intra-arterially in varying doses from 0.5 to 160 ng/kg/min. Mean baseline colonic pressure was 8.9 mm Hg increasing in a dose-dependent manner to 34.6 mm Hg at an SP dose of 40 ng/kg/min. Hereafter, the colonic pressure remained constant. In other series, SP infusion (5-80 ng/kg) was preceded by infusion of hexamethonium (0.5 mg/kg/min, continuous i.v.; n = 7), atropine (0.01 mg/kg/30 min, i.v.; n = 6), by naloxone (0.01 mg/kg/15 min, i.a.; n = 5) or tetrodotoxin (1 microgram/kg/h, i.a.; n = 7). Atropine significantly inhibited the effect of SP on colonic pressure, whereas the other blockers were without influence on the SP-induced colonic pressure. It is concluded that SP has a potent dose-dependent stimulatory effect upon right colonic intraluminal activity of the pig, mediated partly by atropine-sensitive receptors.
Bayat
M
M
Department of Surgery L, Aarhus University Hospital, Denmark.
Lam
G W
GW
Mortensen
J
J
Jensen
S L
SL
D000818:Animals; D002799:Cholinergic Fibers / Q000502:physiology; D003106:Colon / Q000294:innervation / Q000502:physiology; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology*; D011312:Pressure; D013373:Substance P / Q000502:physiology*; D013552:Swine
D013373:Substance P