PT  - JOURNAL ARTICLE
AU  - S Giuliani
AU  - A Lecci
AU  - A Giachetti
AU  - C A Maggi
TI  - Tachykinins and reflexly evoked atropine-resistant motility in the guinea pig colon in vivo.
DP  - 1993 Jun 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1224--1231
VI  - 265
IP  - 3
4099  - http://jpet.aspetjournals.org/content/265/3/1224.short
4100  - http://jpet.aspetjournals.org/content/265/3/1224.full
SO  - J Pharmacol Exp Ther1993 Jun 01; 265
AB  - Distension of a balloon placed in the proximal colon of anesthetized, guanethidine- and naloxone-pretreated guinea pigs elicited a series of long-lasting regular phasic pressure waves which were suppressed by hexamethonium. Activity evoked by a low degree of balloon distension was largely, but not completely, suppressed by atropine. Further balloon distension in atropine-treated animals enabled us to study the effect of tachykinin receptor antagonists on the atropine-resistant and hexamethonium-sensitive response to distension. The selective tachykinin receptor antagonists, (+/-)-CP 96,345 for the NK-1 receptor and L 659,877, MEN 10,376 and SR 48,968 for the NK-2 receptor, inhibited with varying potency the atropine-resistant response to distension. These antagonists also blocked the contraction of the guinea pig colon produced by the i.v. administration of selective NK-1 and NK-2 receptor agonists. In vitro experiments, using mucosa-free circular muscle strips from the guinea pig colon, proved the existence of functional NK-1 and NK-2 receptors in this tissue. We conclude that both NK-1 and NK-2 receptors participate in the atropine-resistant reflex contractions produced by localized balloon distension of the guinea pig colon in vivo.