Kuizenga, M.H. (Merel) (2014) Neurogenic and myogenic motor patterns in the isolated human small intestine. thesis, Medicine.
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Abstract
Background: Myogenic mechanisms, driven by the non-neural pacemaker cells and neurogenic mechanisms, via circuits in the enteric nervous system, combine to generate motor patterns in the gastrointestinal tract of mammals. However, most of our knowledge of the mechanisms has been derived from laboratory animals. While in vivo patterns of human small bowel motility have been described, mechanisms that underlie their generation remain elusive. Aim: To characterize the neurogenic and myogenic motor patterns preserved in large isolated segments of human small intestine. Methods: Human terminal ileum (n=14) from right hemicolectomy resections (due to colonic malignancy), were studied in an organ bath with warm oxygenated Krebs. Motor patterns were recorded in three ways: video-camera for analysing diameter changes; force transducers to measure force generated by the wall; and a fibre-optic manometry catheter to measure intraluminal pressure at 1cm resolution. We recorded 30min of spontaneous activity; 30min of modest, maintained distension (0.5ml Krebs/cm length) and 30min of exposure to lidocaine (300µM) to block neural activity. Results: In 5 of 14 specimens propagating clustered contractions occurred at intervals of 207±76s often induced by fluid distension. These were blocked by lidocaine. Shallow myogenic contractions (ripples), present in the basal and distended phase, became readily visible after lidocaine. Their frequency (~6cpm) was not affected by lidocaine or distension. Conclusion: Our experiments show that isolated segments of human small intestine confirm many of the neurally-dependent motor patterns and the underlying myogenic activity. Our experimental setup provides an ideal test-bed for detailing mechanisms that generate human intestinal motility.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Nieuwenhuijs, dr. VB |
| Supervisor name: | Wattchow, Prof. dr. DA and Department of Physiology and Flinders University and Adelaide, Australia. |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:39 |
| Last Modified: | 25 Jun 2020 10:39 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/101 |
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