Inhibitory Effects and Sympathetic Mechanisms of Distension in the Distal Organs on Small Bowel Motility and Slow Waves in Canine.
Rectal distension (RD) is known to induce intestinal dysmotility. Few studies were performed to compare effects of RD, colon distension (CD) and duodenal distension (DD) on small bowel motility. This study aimed to investigate effects and underlying mechanisms of distensions in these regions on intestinal motility and slow waves. Eight dogs chronically implanted with a duodenal fistula, a proximal colon fistula, and intestinal serosal electrodes were studied in six sessions: control, RD, CD, DD, RD + guanethidine, and CD + guanethidine. Postprandial intestinal contractions and slow waves were recorded for the assessment of intestinal motility. The electrocardiogram was recorded for the assessment of autonomic functions. (1) Isobaric RD and CD suppressed intestinal contractions (contractile index: 6.0 ± 0.4 with RD vs. 9.9 ± 0.9 at baseline, P = 0.001, 5.3 ± 0.2 with CD vs. 7.7 ± 0.8 at baseline, P = 0.008). Guanethidine at 3 mg/kg iv was able to partially block the effects. (2) RD and CD reduced the percentage of normal intestinal slow waves from 92.1 ± 2.8 to 64.2 ± 3.4 % (P < 0.001) and from 90 ± 2.7 to 69.2 ± 3.7 % (P = 0.01), respectively. Guanethidine could eliminate these inhibitory effects. (3) DD did not induce any changes in small intestinal contractions and slow waves (P > 0.05). (4) The spectral analysis of the heart rate variability showed that both RD and CD increased sympathetic activity (LF) and reduced vagal activity (HF) (P < 0.05). Isobaric RD and CD could inhibit postprandial intestinal motility and impair intestinal slow waves, which were mediated via the sympathetic pathway. However, DD at a site proximal to the measurement site did not seem to impair small intestinal contractions or slow waves.
Division of Gastroenterology, University of Texas Medical Branch, Galveston, TX, USA.|Department of Gastroenterology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
Jun
J
Song
Division of Gastroenterology, University of Texas Medical Branch, Galveston, TX, USA.|Ningbo Pace Translational Medical Research Center, Beilun, Ningbo, People's Republic of China.
Jieyun
J
Yin
Division of Gastroenterology, University of Texas Medical Branch, Galveston, TX, USA. jchen184@163.com.|Ningbo Pace Translational Medical Research Center, Beilun, Ningbo, People's Republic of China. jchen184@163.com.|Division of Gastroenterology and Hepatology, Johns Hopkins Center for Neurogastroenterology, Johns Hopkins University, Baltimore, MD, 21224, USA. jchen184@163.com.
Jiande D Z
JD
Chen
D018663:Adrenergic Agents / Q000494:pharmacology; D000818:Animals; D003248:Constipation / Q000503:physiopathology*; D004285:Dogs; D005260:Female; D005769:Gastrointestinal Motility; D006145:Guanethidine / Q000494:pharmacology; D007421:Intestine, Small / Q000294:innervation* / Q000502:physiology / Q000503:physiopathology; D010525:Peripheral Nerves / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000502:physiology / Q000503:physiopathology*
D018663:Adrenergic Agents; D006145:Guanethidine
Colon distension; Heart rate variability; Intestinal motility; Intestinal slow waves; Rectal distension