RAT GASTRODUODENAL MOTILITY IN-VIVO - INVOLVEMENT OF NO AND ATP IN SPONTANEOUS MOTOR-ACTIVITY

Citation
I. Glasgow et al., RAT GASTRODUODENAL MOTILITY IN-VIVO - INVOLVEMENT OF NO AND ATP IN SPONTANEOUS MOTOR-ACTIVITY, American journal of physiology: Gastrointestinal and liver physiology, 38(5), 1998, pp. 889-896
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physiology
ISSN journal
0193-1857
Volume
38
Issue
5
Year of publication
1998
Pages
889 - 896
Database
ISI
SICI code
0193-1857(1998)38:5<889:RGMI-I>2.0.ZU;2-G
Abstract
Our studies of fasted anesthetized rats have shown that all spontaneou s relaxations of the antrum are nitric oxide (NO) dependent. Duodenal motility is patterned into propagating ''grouped'' motor activity inte rposed with ''intergroup'' periods of nonpropagating motor activity; i n the duodenum, only intergroup relaxations are NO dependent. We exami ned the involvement of NO and ATP in spontaneous motor activities of t he gastroduodenum in vivo: contractions and relaxations were recorded and analyzed simultaneously from the antrum (S-1) and proximal duodenu m (D-1) of anesthetized Sprague-Dawley rats (n = 10/group), using extr aluminal foil strain gauges. Treatment with the NO synthase inhibitor N-G-nitro-L-arginine methyl ester (L-NAME; 10 mg/kg iv) attenuated (P < 0.05) antral and intergroup relaxations, whereas grouped relaxations were enhanced (P < 0.05). These effects were reversed with L-arginine (300 mg/kg iv). L-NAME also increased (P < 0.05) the amplitude of duo denal contractions. ATP (8 mg.kg(-1).min(-1) iv) stimulated relaxation s at S-1 and D-1 that were blocked by the P-2-purinoceptor antagonist suramin (60 mg/kg iv). This treatment did not affect spontaneous antra l relaxations; however, duodenal grouped relaxations were attenuated. Desensitization to the P-2x-purinoceptor agonist alpha,beta-methylene ATP (300 mu g/kg iv) gave results similar to suramin. In contrast, the P-2y-purinoceptor agonist 2-methylthio-ATP (2-MeS-ATP; 360 mu g/kg iv ) evoked duodenal relaxations that were attenuated by L-NAME, and dese nsitization to 2-MeS-ATP attenuated intergroup relaxations. Spontaneou s relaxations of the rat antrum and duodenal intergroup relaxations ar e NO dependent. Both gut regions relax in response to systemically adm inistered ATP; this response is sensitive to suramin. Grouped duodenal relaxations display functional sensitivity to suramin and P-2x-purino ceptor desensitization, indicative of the involvement of ATP and P-2x purinoceptors. P-2y purinoceptors must also be present; however, these occur on elements releasing NO. Although NO does not mediate grouped relaxations or duodenal contractions, the sensitivity of these respons es to L-NAME indicates that the pathway(s) controlling these responses is modulated by NO.